Import prebuilt clang toolchain for linux.
diff --git a/linux-x64/clang/include/llvm/Analysis/RegionInfoImpl.h b/linux-x64/clang/include/llvm/Analysis/RegionInfoImpl.h
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+//===- 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/GraphTraits.h"
+#include "llvm/ADT/PostOrderIterator.h"
+#include "llvm/ADT/STLExtras.h"
+#include "llvm/ADT/SmallVector.h"
+#include "llvm/ADT/iterator_range.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 "llvm/Support/raw_ostream.h"
+#include <algorithm>
+#include <cassert>
+#include <iterator>
+#include <memory>
+#include <set>
+#include <string>
+#include <type_traits>
+#include <vector>
+
+#define DEBUG_TYPE "region"
+
+namespace llvm {
+
+//===----------------------------------------------------------------------===//
+/// 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() {
+  // 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 (std::unique_ptr<RegionT> &Child : *R) {
+      if (Child->getEntry() == OldEntry)
+        RegionQueue.push_back(Child.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 (std::unique_ptr<RegionT> &Child : *R) {
+      if (Child->getExit() == OldExit)
+        RegionQueue.push_back(Child.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 *enteringBlock = nullptr;
+
+  for (BlockT *Pred : make_range(InvBlockTraits::child_begin(entry),
+                                 InvBlockTraits::child_end(entry))) {
+    if (DT->getNode(Pred) && !contains(Pred)) {
+      if (enteringBlock)
+        return nullptr;
+
+      enteringBlock = Pred;
+    }
+  }
+
+  return enteringBlock;
+}
+
+template <class Tr>
+bool RegionBase<Tr>::getExitingBlocks(
+    SmallVectorImpl<BlockT *> &Exitings) const {
+  bool CoverAll = true;
+
+  if (!exit)
+    return CoverAll;
+
+  for (PredIterTy PI = InvBlockTraits::child_begin(exit),
+                  PE = InvBlockTraits::child_end(exit);
+       PI != PE; ++PI) {
+    BlockT *Pred = *PI;
+    if (contains(Pred)) {
+      Exitings.push_back(Pred);
+      continue;
+    }
+
+    CoverAll = false;
+  }
+
+  return CoverAll;
+}
+
+template <class Tr>
+typename RegionBase<Tr>::BlockT *RegionBase<Tr>::getExitingBlock() const {
+  BlockT *exit = getExit();
+  BlockT *exitingBlock = nullptr;
+
+  if (!exit)
+    return nullptr;
+
+  for (BlockT *Pred : make_range(InvBlockTraits::child_begin(exit),
+                                 InvBlockTraits::child_end(exit))) {
+    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))
+    report_fatal_error("Broken region found: enumerated BB not in region!");
+
+  BlockT *entry = getEntry(), *exit = getExit();
+
+  for (BlockT *Succ :
+       make_range(BlockTraits::child_begin(BB), BlockTraits::child_end(BB))) {
+    if (!contains(Succ) && exit != Succ)
+      report_fatal_error("Broken region found: edges leaving the region must go "
+                         "to the exit node!");
+  }
+
+  if (entry != BB) {
+    for (BlockT *Pred : make_range(InvBlockTraits::child_begin(BB),
+                                   InvBlockTraits::child_end(BB))) {
+      if (!contains(Pred))
+        report_fatal_error("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 (BlockT *Succ :
+       make_range(BlockTraits::child_begin(BB), BlockTraits::child_end(BB))) {
+    if (Succ != exit && visited->find(Succ) == visited->end())
+      verifyWalk(Succ, 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 (const std::unique_ptr<RegionT> &R : *this)
+    R->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 {
+  using RegionT = typename Tr::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()) {
+    auto Deconst = const_cast<RegionBase<Tr> *>(this);
+    typename BBNodeMapT::value_type V = {
+        BB,
+        llvm::make_unique<RegionNodeT>(static_cast<RegionT *>(Deconst), BB)};
+    at = BBNodeMap.insert(std::move(V)).first;
+  }
+  return at->second.get();
+}
+
+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 (std::unique_ptr<RegionT> &R : *this) {
+    R->parent = To;
+    To->children.push_back(std::move(R));
+  }
+  children.clear();
+}
+
+template <class Tr>
+void RegionBase<Tr>::addSubRegion(RegionT *SubRegion, bool moveChildren) {
+  assert(!SubRegion->parent && "SubRegion already has a parent!");
+  assert(llvm::find_if(*this,
+                       [&](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 (RegionNodeT *Element : elements()) {
+    if (!Element->isSubRegion()) {
+      BlockT *BB = Element->template getNodeAs<BlockT>();
+
+      if (SubRegion->contains(BB))
+        RI->setRegionFor(BB, SubRegion);
+    }
+  }
+
+  std::vector<std::unique_ptr<RegionT>> Keep;
+  for (std::unique_ptr<RegionT> &R : *this) {
+    if (SubRegion->contains(R.get()) && R.get() != SubRegion) {
+      R->parent = SubRegion;
+      SubRegion->children.push_back(std::move(R));
+    } else
+      Keep.push_back(std::move(R));
+  }
+
+  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 =
+      llvm::find_if(children, [&](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 (BlockT *Pred : make_range(InvBlockTraits::child_begin(getExit()),
+                                   InvBlockTraits::child_end(getExit())))
+      if (!contains(Pred))
+        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 (BlockT *Pred : make_range(InvBlockTraits::child_begin(getExit()),
+                                 InvBlockTraits::child_end(getExit()))) {
+    if (!(contains(Pred) || R->contains(Pred)))
+      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 RegionNodeT *Element : elements()) {
+        OS << *Element << ", "; // TODO: remove the last ",
+      }
+    }
+
+    OS << '\n';
+  }
+
+  if (print_tree) {
+    for (const std::unique_ptr<RegionT> &R : *this)
+      R->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() {
+  BBNodeMap.clear();
+  for (std::unique_ptr<RegionT> &R : *this)
+    R->clearNodeCache();
+}
+
+//===----------------------------------------------------------------------===//
+// RegionInfoBase implementation
+//
+
+template <class Tr>
+RegionInfoBase<Tr>::RegionInfoBase() = default;
+
+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 (const typename Tr::RegionNodeT *Element : R->elements()) {
+    if (Element->isSubRegion()) {
+      const RegionT *SR = Element->template getNodeAs<RegionT>();
+      verifyBBMap(SR);
+    } else {
+      BlockT *BB = Element->template getNodeAs<BlockT>();
+      if (getRegionFor(BB) != R)
+        report_fatal_error("BB map does not match region nesting");
+    }
+  }
+}
+
+template <class Tr>
+bool RegionInfoBase<Tr>::isCommonDomFrontier(BlockT *BB, BlockT *entry,
+                                             BlockT *exit) const {
+  for (BlockT *P : make_range(InvBlockTraits::child_begin(BB),
+                              InvBlockTraits::child_end(BB))) {
+    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!");
+
+  using DST = typename DomFrontierT::DomSetType;
+
+  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 (BlockT *Succ : *entrySuccs) {
+    if (Succ == exit || Succ == entry)
+      continue;
+    if (exitSuccs->find(Succ) == exitSuccs->end())
+      return false;
+    if (!isCommonDomFrontier(Succ, entry, exit))
+      return false;
+  }
+
+  // Do not allow edges pointing into the region.
+  for (BlockT *Succ : *exitSuccs) {
+    if (DT->properlyDominates(entry, Succ) && Succ != 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({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) {
+  using FuncPtrT = typename std::add_pointer<FuncT>::type;
+
+  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 (DomTreeNodeBase<BlockT> *C : *N) {
+    buildRegionsTree(C, 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 (BlockT *Pred : make_range(InvBlockTraits::child_begin(Exit),
+                                   InvBlockTraits::child_end(Exit))) {
+      if (!R->contains(Pred) && !ExitR->contains(Pred))
+        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) {
+  using FuncPtrT = typename std::add_pointer<FuncT>::type;
+
+  // 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);
+}
+
+} // end namespace llvm
+
+#undef DEBUG_TYPE
+
+#endif // LLVM_ANALYSIS_REGIONINFOIMPL_H