src/llvm/include/llvm/Analysis/RegionInfoImpl.h

   1 //===- RegionInfoImpl.h - SESE region detection analysis --------*- C++ -*-===//
   2 //
   3 //                     The LLVM Compiler Infrastructure
   4 //
   5 // This file is distributed under the University of Illinois Open Source
   6 // License. See LICENSE.TXT for details.
   7 //
   8 //===----------------------------------------------------------------------===//
   9 // Detects single entry single exit regions in the control flow graph.
  10 //===----------------------------------------------------------------------===//
  11
  12 #ifndef LLVM_ANALYSIS_REGIONINFOIMPL_H
  13 #define LLVM_ANALYSIS_REGIONINFOIMPL_H
  14
  15 #include "llvm/ADT/PostOrderIterator.h"
  16 #include "llvm/Analysis/DominanceFrontier.h"
  17 #include "llvm/Analysis/LoopInfo.h"
  18 #include "llvm/Analysis/PostDominators.h"
  19 #include "llvm/Analysis/RegionInfo.h"
  20 #include "llvm/Analysis/RegionIterator.h"
  21 #include "llvm/Support/CommandLine.h"
  22 #include "llvm/Support/Debug.h"
  23 #include "llvm/Support/ErrorHandling.h"
  24 #include <algorithm>
  25 #include <iterator>
  26 #include <set>
  27
  28 namespace llvm {
  29
  30 #define DEBUG_TYPE "region"
  31
  32 //===----------------------------------------------------------------------===//
  33 /// RegionBase Implementation
  34 template <class Tr>
  35 RegionBase<Tr>::RegionBase(BlockT *Entry, BlockT *Exit,
  36                            typename Tr::RegionInfoT *RInfo, DomTreeT *dt,
  37                            RegionT *Parent)
  38     : RegionNodeBase<Tr>(Parent, Entry, 1), RI(RInfo), DT(dt), exit(Exit) {}
  39
  40 template <class Tr>
  41 RegionBase<Tr>::~RegionBase() {
  42   // Free the cached nodes.
  43   for (typename BBNodeMapT::iterator it = BBNodeMap.begin(),
  44                                      ie = BBNodeMap.end();
  45        it != ie; ++it)
  46     delete it->second;
  47
  48   // Only clean the cache for this Region. Caches of child Regions will be
  49   // cleaned when the child Regions are deleted.
  50   BBNodeMap.clear();
  51 }
  52
  53 template <class Tr>
  54 void RegionBase<Tr>::replaceEntry(BlockT *BB) {
  55   this->entry.setPointer(BB);
  56 }
  57
  58 template <class Tr>
  59 void RegionBase<Tr>::replaceExit(BlockT *BB) {
  60   assert(exit && "No exit to replace!");
  61   exit = BB;
  62 }
  63
  64 template <class Tr>
  65 void RegionBase<Tr>::replaceEntryRecursive(BlockT *NewEntry) {
  66   std::vector<RegionT *> RegionQueue;
  67   BlockT *OldEntry = getEntry();
  68
  69   RegionQueue.push_back(static_cast<RegionT *>(this));
  70   while (!RegionQueue.empty()) {
  71     RegionT *R = RegionQueue.back();
  72     RegionQueue.pop_back();
  73
  74     R->replaceEntry(NewEntry);
  75     for (typename RegionT::const_iterator RI = R->begin(), RE = R->end();
  76          RI != RE; ++RI) {
  77       if ((*RI)->getEntry() == OldEntry)
  78         RegionQueue.push_back(RI->get());
  79     }
  80   }
  81 }
  82
  83 template <class Tr>
  84 void 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 (typename RegionT::const_iterator RI = R->begin(), RE = R->end();
  95          RI != RE; ++RI) {
  96       if ((*RI)->getExit() == OldExit)
  97         RegionQueue.push_back(RI->get());
  98     }
  99   }
 100 }
 101
 102 template <class Tr>
 103 bool RegionBase<Tr>::contains(const BlockT *B) const {
 104   BlockT *BB = const_cast<BlockT *>(B);
 105
 106   if (!DT->getNode(BB))
 107     return false;
 108
 109   BlockT *entry = getEntry(), *exit = getExit();
 110
 111   // Toplevel region.
 112   if (!exit)
 113     return true;
 114
 115   return (DT->dominates(entry, BB) &&
 116           !(DT->dominates(exit, BB) && DT->dominates(entry, exit)));
 117 }
 118
 119 template <class Tr>
 120 bool RegionBase<Tr>::contains(const LoopT *L) const {
 121   // BBs that are not part of any loop are element of the Loop
 122   // described by the NULL pointer. This loop is not part of any region,
 123   // except if the region describes the whole function.
 124   if (!L)
 125     return getExit() == nullptr;
 126
 127   if (!contains(L->getHeader()))
 128     return false;
 129
 130   SmallVector<BlockT *, 8> ExitingBlocks;
 131   L->getExitingBlocks(ExitingBlocks);
 132
 133   for (BlockT *BB : ExitingBlocks) {
 134     if (!contains(BB))
 135       return false;
 136   }
 137
 138   return true;
 139 }
 140
 141 template <class Tr>
 142 typename Tr::LoopT *RegionBase<Tr>::outermostLoopInRegion(LoopT *L) const {
 143   if (!contains(L))
 144     return nullptr;
 145
 146   while (L && contains(L->getParentLoop())) {
 147     L = L->getParentLoop();
 148   }
 149
 150   return L;
 151 }
 152
 153 template <class Tr>
 154 typename Tr::LoopT *RegionBase<Tr>::outermostLoopInRegion(LoopInfoT *LI,
 155                                                           BlockT *BB) const {
 156   assert(LI && BB && "LI and BB cannot be null!");
 157   LoopT *L = LI->getLoopFor(BB);
 158   return outermostLoopInRegion(L);
 159 }
 160
 161 template <class Tr>
 162 typename RegionBase<Tr>::BlockT *RegionBase<Tr>::getEnteringBlock() const {
 163   BlockT *entry = getEntry();
 164   BlockT *Pred;
 165   BlockT *enteringBlock = nullptr;
 166
 167   for (PredIterTy PI = InvBlockTraits::child_begin(entry),
 168                   PE = InvBlockTraits::child_end(entry);
 169        PI != PE; ++PI) {
 170     Pred = *PI;
 171     if (DT->getNode(Pred) && !contains(Pred)) {
 172       if (enteringBlock)
 173         return nullptr;
 174
 175       enteringBlock = Pred;
 176     }
 177   }
 178
 179   return enteringBlock;
 180 }
 181
 182 template <class Tr>
 183 typename RegionBase<Tr>::BlockT *RegionBase<Tr>::getExitingBlock() const {
 184   BlockT *exit = getExit();
 185   BlockT *Pred;
 186   BlockT *exitingBlock = nullptr;
 187
 188   if (!exit)
 189     return nullptr;
 190
 191   for (PredIterTy PI = InvBlockTraits::child_begin(exit),
 192                   PE = InvBlockTraits::child_end(exit);
 193        PI != PE; ++PI) {
 194     Pred = *PI;
 195     if (contains(Pred)) {
 196       if (exitingBlock)
 197         return nullptr;
 198
 199       exitingBlock = Pred;
 200     }
 201   }
 202
 203   return exitingBlock;
 204 }
 205
 206 template <class Tr>
 207 bool RegionBase<Tr>::isSimple() const {
 208   return !isTopLevelRegion() && getEnteringBlock() && getExitingBlock();
 209 }
 210
 211 template <class Tr>
 212 std::string RegionBase<Tr>::getNameStr() const {
 213   std::string exitName;
 214   std::string entryName;
 215
 216   if (getEntry()->getName().empty()) {
 217     raw_string_ostream OS(entryName);
 218
 219     getEntry()->printAsOperand(OS, false);
 220   } else
 221     entryName = getEntry()->getName();
 222
 223   if (getExit()) {
 224     if (getExit()->getName().empty()) {
 225       raw_string_ostream OS(exitName);
 226
 227       getExit()->printAsOperand(OS, false);
 228     } else
 229       exitName = getExit()->getName();
 230   } else
 231     exitName = "<Function Return>";
 232
 233   return entryName + " => " + exitName;
 234 }
 235
 236 template <class Tr>
 237 void RegionBase<Tr>::verifyBBInRegion(BlockT *BB) const {
 238   if (!contains(BB))
 239     llvm_unreachable("Broken region found!");
 240
 241   BlockT *entry = getEntry(), *exit = getExit();
 242
 243   for (SuccIterTy SI = BlockTraits::child_begin(BB),
 244                   SE = BlockTraits::child_end(BB);
 245        SI != SE; ++SI) {
 246     if (!contains(*SI) && exit != *SI)
 247       llvm_unreachable("Broken region found!");
 248   }
 249
 250   if (entry != BB) {
 251     for (PredIterTy SI = InvBlockTraits::child_begin(BB),
 252                     SE = InvBlockTraits::child_end(BB);
 253          SI != SE; ++SI) {
 254       if (!contains(*SI))
 255         llvm_unreachable("Broken region found!");
 256     }
 257   }
 258 }
 259
 260 template <class Tr>
 261 void RegionBase<Tr>::verifyWalk(BlockT *BB, std::set<BlockT *> *visited) const {
 262   BlockT *exit = getExit();
 263
 264   visited->insert(BB);
 265
 266   verifyBBInRegion(BB);
 267
 268   for (SuccIterTy SI = BlockTraits::child_begin(BB),
 269                   SE = BlockTraits::child_end(BB);
 270        SI != SE; ++SI) {
 271     if (*SI != exit && visited->find(*SI) == visited->end())
 272       verifyWalk(*SI, visited);
 273   }
 274 }
 275
 276 template <class Tr>
 277 void RegionBase<Tr>::verifyRegion() const {
 278   // Only do verification when user wants to, otherwise this expensive check
 279   // will be invoked by PMDataManager::verifyPreservedAnalysis when
 280   // a regionpass (marked PreservedAll) finish.
 281   if (!RegionInfoBase<Tr>::VerifyRegionInfo)
 282     return;
 283
 284   std::set<BlockT *> visited;
 285   verifyWalk(getEntry(), &visited);
 286 }
 287
 288 template <class Tr>
 289 void RegionBase<Tr>::verifyRegionNest() const {
 290   for (typename RegionT::const_iterator RI = begin(), RE = end(); RI != RE;
 291        ++RI)
 292     (*RI)->verifyRegionNest();
 293
 294   verifyRegion();
 295 }
 296
 297 template <class Tr>
 298 typename RegionBase<Tr>::element_iterator RegionBase<Tr>::element_begin() {
 299   return GraphTraits<RegionT *>::nodes_begin(static_cast<RegionT *>(this));
 300 }
 301
 302 template <class Tr>
 303 typename RegionBase<Tr>::element_iterator RegionBase<Tr>::element_end() {
 304   return GraphTraits<RegionT *>::nodes_end(static_cast<RegionT *>(this));
 305 }
 306
 307 template <class Tr>
 308 typename RegionBase<Tr>::const_element_iterator
 309 RegionBase<Tr>::element_begin() const {
 310   return GraphTraits<const RegionT *>::nodes_begin(
 311       static_cast<const RegionT *>(this));
 312 }
 313
 314 template <class Tr>
 315 typename RegionBase<Tr>::const_element_iterator
 316 RegionBase<Tr>::element_end() const {
 317   return GraphTraits<const RegionT *>::nodes_end(
 318       static_cast<const RegionT *>(this));
 319 }
 320
 321 template <class Tr>
 322 typename Tr::RegionT *RegionBase<Tr>::getSubRegionNode(BlockT *BB) const {
 323   typedef typename Tr::RegionT RegionT;
 324   RegionT *R = RI->getRegionFor(BB);
 325
 326   if (!R || R == this)
 327     return nullptr;
 328
 329   // If we pass the BB out of this region, that means our code is broken.
 330   assert(contains(R) && "BB not in current region!");
 331
 332   while (contains(R->getParent()) && R->getParent() != this)
 333     R = R->getParent();
 334
 335   if (R->getEntry() != BB)
 336     return nullptr;
 337
 338   return R;
 339 }
 340
 341 template <class Tr>
 342 typename Tr::RegionNodeT *RegionBase<Tr>::getBBNode(BlockT *BB) const {
 343   assert(contains(BB) && "Can get BB node out of this region!");
 344
 345   typename BBNodeMapT::const_iterator at = BBNodeMap.find(BB);
 346
 347   if (at != BBNodeMap.end())
 348     return at->second;
 349
 350   auto Deconst = const_cast<RegionBase<Tr> *>(this);
 351   RegionNodeT *NewNode = new RegionNodeT(static_cast<RegionT *>(Deconst), BB);
 352   BBNodeMap.insert(std::make_pair(BB, NewNode));
 353   return NewNode;
 354 }
 355
 356 template <class Tr>
 357 typename Tr::RegionNodeT *RegionBase<Tr>::getNode(BlockT *BB) const {
 358   assert(contains(BB) && "Can get BB node out of this region!");
 359   if (RegionT *Child = getSubRegionNode(BB))
 360     return Child->getNode();
 361
 362   return getBBNode(BB);
 363 }
 364
 365 template <class Tr>
 366 void RegionBase<Tr>::transferChildrenTo(RegionT *To) {
 367   for (iterator I = begin(), E = end(); I != E; ++I) {
 368     (*I)->parent = To;
 369     To->children.push_back(std::move(*I));
 370   }
 371   children.clear();
 372 }
 373
 374 template <class Tr>
 375 void RegionBase<Tr>::addSubRegion(RegionT *SubRegion, bool moveChildren) {
 376   assert(!SubRegion->parent && "SubRegion already has a parent!");
 377   assert(std::find_if(begin(), end(), [&](const std::unique_ptr<RegionT> &R) {
 378            return R.get() == SubRegion;
 379          }) == children.end() &&
 380          "Subregion already exists!");
 381
 382   SubRegion->parent = static_cast<RegionT *>(this);
 383   children.push_back(std::unique_ptr<RegionT>(SubRegion));
 384
 385   if (!moveChildren)
 386     return;
 387
 388   assert(SubRegion->children.empty() &&
 389          "SubRegions that contain children are not supported");
 390
 391   for (element_iterator I = element_begin(), E = element_end(); I != E; ++I) {
 392     if (!(*I)->isSubRegion()) {
 393       BlockT *BB = (*I)->template getNodeAs<BlockT>();
 394
 395       if (SubRegion->contains(BB))
 396         RI->setRegionFor(BB, SubRegion);
 397     }
 398   }
 399
 400   std::vector<std::unique_ptr<RegionT>> Keep;
 401   for (iterator I = begin(), E = end(); I != E; ++I) {
 402     if (SubRegion->contains(I->get()) && I->get() != SubRegion) {
 403       (*I)->parent = SubRegion;
 404       SubRegion->children.push_back(std::move(*I));
 405     } else
 406       Keep.push_back(std::move(*I));
 407   }
 408
 409   children.clear();
 410   children.insert(
 411       children.begin(),
 412       std::move_iterator<typename RegionSet::iterator>(Keep.begin()),
 413       std::move_iterator<typename RegionSet::iterator>(Keep.end()));
 414 }
 415
 416 template <class Tr>
 417 typename Tr::RegionT *RegionBase<Tr>::removeSubRegion(RegionT *Child) {
 418   assert(Child->parent == this && "Child is not a child of this region!");
 419   Child->parent = nullptr;
 420   typename RegionSet::iterator I = std::find_if(
 421       children.begin(), children.end(),
 422       [&](const std::unique_ptr<RegionT> &R) { return R.get() == Child; });
 423   assert(I != children.end() && "Region does not exit. Unable to remove.");
 424   children.erase(children.begin() + (I - begin()));
 425   return Child;
 426 }
 427
 428 template <class Tr>
 429 unsigned RegionBase<Tr>::getDepth() const {
 430   unsigned Depth = 0;
 431
 432   for (RegionT *R = getParent(); R != nullptr; R = R->getParent())
 433     ++Depth;
 434
 435   return Depth;
 436 }
 437
 438 template <class Tr>
 439 typename Tr::RegionT *RegionBase<Tr>::getExpandedRegion() const {
 440   unsigned NumSuccessors = Tr::getNumSuccessors(exit);
 441
 442   if (NumSuccessors == 0)
 443     return nullptr;
 444
 445   for (PredIterTy PI = InvBlockTraits::child_begin(getExit()),
 446                   PE = InvBlockTraits::child_end(getExit());
 447        PI != PE; ++PI) {
 448     if (!DT->dominates(getEntry(), *PI))
 449       return nullptr;
 450   }
 451
 452   RegionT *R = RI->getRegionFor(exit);
 453
 454   if (R->getEntry() != exit) {
 455     if (Tr::getNumSuccessors(exit) == 1)
 456       return new RegionT(getEntry(), *BlockTraits::child_begin(exit), RI, DT);
 457     return nullptr;
 458   }
 459
 460   while (R->getParent() && R->getParent()->getEntry() == exit)
 461     R = R->getParent();
 462
 463   if (!DT->dominates(getEntry(), R->getExit())) {
 464     for (PredIterTy PI = InvBlockTraits::child_begin(getExit()),
 465                     PE = InvBlockTraits::child_end(getExit());
 466          PI != PE; ++PI) {
 467       if (!DT->dominates(R->getExit(), *PI))
 468         return nullptr;
 469     }
 470   }
 471
 472   return new RegionT(getEntry(), R->getExit(), RI, DT);
 473 }
 474
 475 template <class Tr>
 476 void RegionBase<Tr>::print(raw_ostream &OS, bool print_tree, unsigned level,
 477                            PrintStyle Style) const {
 478   if (print_tree)
 479     OS.indent(level * 2) << '[' << level << "] " << getNameStr();
 480   else
 481     OS.indent(level * 2) << getNameStr();
 482
 483   OS << '\n';
 484
 485   if (Style != PrintNone) {
 486     OS.indent(level * 2) << "{\n";
 487     OS.indent(level * 2 + 2);
 488
 489     if (Style == PrintBB) {
 490       for (const auto &BB : blocks())
 491         OS << BB->getName() << ", "; // TODO: remove the last ","
 492     } else if (Style == PrintRN) {
 493       for (const_element_iterator I = element_begin(), E = element_end();
 494            I != E; ++I) {
 495         OS << **I << ", "; // TODO: remove the last ",
 496       }
 497     }
 498
 499     OS << '\n';
 500   }
 501
 502   if (print_tree) {
 503     for (const_iterator RI = begin(), RE = end(); RI != RE; ++RI)
 504       (*RI)->print(OS, print_tree, level + 1, Style);
 505   }
 506
 507   if (Style != PrintNone)
 508     OS.indent(level * 2) << "} \n";
 509 }
 510
 511 #if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
 512 template <class Tr>
 513 void RegionBase<Tr>::dump() const {
 514   print(dbgs(), true, getDepth(), RegionInfoBase<Tr>::printStyle);
 515 }
 516 #endif
 517
 518 template <class Tr>
 519 void RegionBase<Tr>::clearNodeCache() {
 520   // Free the cached nodes.
 521   for (typename BBNodeMapT::iterator I = BBNodeMap.begin(),
 522                                      IE = BBNodeMap.end();
 523        I != IE; ++I)
 524     delete I->second;
 525
 526   BBNodeMap.clear();
 527   for (typename RegionT::iterator RI = begin(), RE = end(); RI != RE; ++RI)
 528     (*RI)->clearNodeCache();
 529 }
 530
 531 //===----------------------------------------------------------------------===//
 532 // RegionInfoBase implementation
 533 //
 534
 535 template <class Tr>
 536 RegionInfoBase<Tr>::RegionInfoBase()
 537     : TopLevelRegion(nullptr) {}
 538
 539 template <class Tr>
 540 RegionInfoBase<Tr>::~RegionInfoBase() {
 541   releaseMemory();
 542 }
 543
 544 template <class Tr>
 545 bool RegionInfoBase<Tr>::isCommonDomFrontier(BlockT *BB, BlockT *entry,
 546                                              BlockT *exit) const {
 547   for (PredIterTy PI = InvBlockTraits::child_begin(BB),
 548                   PE = InvBlockTraits::child_end(BB);
 549        PI != PE; ++PI) {
 550     BlockT *P = *PI;
 551     if (DT->dominates(entry, P) && !DT->dominates(exit, P))
 552       return false;
 553   }
 554
 555   return true;
 556 }
 557
 558 template <class Tr>
 559 bool RegionInfoBase<Tr>::isRegion(BlockT *entry, BlockT *exit) const {
 560   assert(entry && exit && "entry and exit must not be null!");
 561   typedef typename DomFrontierT::DomSetType DST;
 562
 563   DST *entrySuccs = &DF->find(entry)->second;
 564
 565   // Exit is the header of a loop that contains the entry. In this case,
 566   // the dominance frontier must only contain the exit.
 567   if (!DT->dominates(entry, exit)) {
 568     for (typename DST::iterator SI = entrySuccs->begin(),
 569                                 SE = entrySuccs->end();
 570          SI != SE; ++SI) {
 571       if (*SI != exit && *SI != entry)
 572         return false;
 573     }
 574
 575     return true;
 576   }
 577
 578   DST *exitSuccs = &DF->find(exit)->second;
 579
 580   // Do not allow edges leaving the region.
 581   for (typename DST::iterator SI = entrySuccs->begin(), SE = entrySuccs->end();
 582        SI != SE; ++SI) {
 583     if (*SI == exit || *SI == entry)
 584       continue;
 585     if (exitSuccs->find(*SI) == exitSuccs->end())
 586       return false;
 587     if (!isCommonDomFrontier(*SI, entry, exit))
 588       return false;
 589   }
 590
 591   // Do not allow edges pointing into the region.
 592   for (typename DST::iterator SI = exitSuccs->begin(), SE = exitSuccs->end();
 593        SI != SE; ++SI) {
 594     if (DT->properlyDominates(entry, *SI) && *SI != exit)
 595       return false;
 596   }
 597
 598   return true;
 599 }
 600
 601 template <class Tr>
 602 void RegionInfoBase<Tr>::insertShortCut(BlockT *entry, BlockT *exit,
 603                                         BBtoBBMap *ShortCut) const {
 604   assert(entry && exit && "entry and exit must not be null!");
 605
 606   typename BBtoBBMap::iterator e = ShortCut->find(exit);
 607
 608   if (e == ShortCut->end())
 609     // No further region at exit available.
 610     (*ShortCut)[entry] = exit;
 611   else {
 612     // We found a region e that starts at exit. Therefore (entry, e->second)
 613     // is also a region, that is larger than (entry, exit). Insert the
 614     // larger one.
 615     BlockT *BB = e->second;
 616     (*ShortCut)[entry] = BB;
 617   }
 618 }
 619
 620 template <class Tr>
 621 typename Tr::DomTreeNodeT *
 622 RegionInfoBase<Tr>::getNextPostDom(DomTreeNodeT *N, BBtoBBMap *ShortCut) const {
 623   typename BBtoBBMap::iterator e = ShortCut->find(N->getBlock());
 624
 625   if (e == ShortCut->end())
 626     return N->getIDom();
 627
 628   return PDT->getNode(e->second)->getIDom();
 629 }
 630
 631 template <class Tr>
 632 bool RegionInfoBase<Tr>::isTrivialRegion(BlockT *entry, BlockT *exit) const {
 633   assert(entry && exit && "entry and exit must not be null!");
 634
 635   unsigned num_successors =
 636       BlockTraits::child_end(entry) - BlockTraits::child_begin(entry);
 637
 638   if (num_successors <= 1 && exit == *(BlockTraits::child_begin(entry)))
 639     return true;
 640
 641   return false;
 642 }
 643
 644 template <class Tr>
 645 typename Tr::RegionT *RegionInfoBase<Tr>::createRegion(BlockT *entry,
 646                                                        BlockT *exit) {
 647   assert(entry && exit && "entry and exit must not be null!");
 648
 649   if (isTrivialRegion(entry, exit))
 650     return nullptr;
 651
 652   RegionT *region =
 653       new RegionT(entry, exit, static_cast<RegionInfoT *>(this), DT);
 654   BBtoRegion.insert(std::make_pair(entry, region));
 655
 656 #ifdef XDEBUG
 657   region->verifyRegion();
 658 #else
 659   DEBUG(region->verifyRegion());
 660 #endif
 661
 662   updateStatistics(region);
 663   return region;
 664 }
 665
 666 template <class Tr>
 667 void RegionInfoBase<Tr>::findRegionsWithEntry(BlockT *entry,
 668                                               BBtoBBMap *ShortCut) {
 669   assert(entry);
 670
 671   DomTreeNodeT *N = PDT->getNode(entry);
 672   if (!N)
 673     return;
 674
 675   RegionT *lastRegion = nullptr;
 676   BlockT *lastExit = entry;
 677
 678   // As only a BasicBlock that postdominates entry can finish a region, walk the
 679   // post dominance tree upwards.
 680   while ((N = getNextPostDom(N, ShortCut))) {
 681     BlockT *exit = N->getBlock();
 682
 683     if (!exit)
 684       break;
 685
 686     if (isRegion(entry, exit)) {
 687       RegionT *newRegion = createRegion(entry, exit);
 688
 689       if (lastRegion)
 690         newRegion->addSubRegion(lastRegion);
 691
 692       lastRegion = newRegion;
 693       lastExit = exit;
 694     }
 695
 696     // This can never be a region, so stop the search.
 697     if (!DT->dominates(entry, exit))
 698       break;
 699   }
 700
 701   // Tried to create regions from entry to lastExit.  Next time take a
 702   // shortcut from entry to lastExit.
 703   if (lastExit != entry)
 704     insertShortCut(entry, lastExit, ShortCut);
 705 }
 706
 707 template <class Tr>
 708 void RegionInfoBase<Tr>::scanForRegions(FuncT &F, BBtoBBMap *ShortCut) {
 709   typedef typename std::add_pointer<FuncT>::type FuncPtrT;
 710   BlockT *entry = GraphTraits<FuncPtrT>::getEntryNode(&F);
 711   DomTreeNodeT *N = DT->getNode(entry);
 712
 713   // Iterate over the dominance tree in post order to start with the small
 714   // regions from the bottom of the dominance tree.  If the small regions are
 715   // detected first, detection of bigger regions is faster, as we can jump
 716   // over the small regions.
 717   for (po_iterator<DomTreeNodeT *> FI = po_begin(N), FE = po_end(N); FI != FE;
 718        ++FI) {
 719     findRegionsWithEntry(FI->getBlock(), ShortCut);
 720   }
 721 }
 722
 723 template <class Tr>
 724 typename Tr::RegionT *RegionInfoBase<Tr>::getTopMostParent(RegionT *region) {
 725   while (region->getParent())
 726     region = region->getParent();
 727
 728   return region;
 729 }
 730
 731 template <class Tr>
 732 void RegionInfoBase<Tr>::buildRegionsTree(DomTreeNodeT *N, RegionT *region) {
 733   BlockT *BB = N->getBlock();
 734
 735   // Passed region exit
 736   while (BB == region->getExit())
 737     region = region->getParent();
 738
 739   typename BBtoRegionMap::iterator it = BBtoRegion.find(BB);
 740
 741   // This basic block is a start block of a region. It is already in the
 742   // BBtoRegion relation. Only the child basic blocks have to be updated.
 743   if (it != BBtoRegion.end()) {
 744     RegionT *newRegion = it->second;
 745     region->addSubRegion(getTopMostParent(newRegion));
 746     region = newRegion;
 747   } else {
 748     BBtoRegion[BB] = region;
 749   }
 750
 751   for (typename DomTreeNodeT::iterator CI = N->begin(), CE = N->end(); CI != CE;
 752        ++CI) {
 753     buildRegionsTree(*CI, region);
 754   }
 755 }
 756
 757 #ifdef XDEBUG
 758 template <class Tr>
 759 bool RegionInfoBase<Tr>::VerifyRegionInfo = true;
 760 #else
 761 template <class Tr>
 762 bool RegionInfoBase<Tr>::VerifyRegionInfo = false;
 763 #endif
 764
 765 template <class Tr>
 766 typename Tr::RegionT::PrintStyle RegionInfoBase<Tr>::printStyle =
 767     RegionBase<Tr>::PrintNone;
 768
 769 template <class Tr>
 770 void RegionInfoBase<Tr>::print(raw_ostream &OS) const {
 771   OS << "Region tree:\n";
 772   TopLevelRegion->print(OS, true, 0, printStyle);
 773   OS << "End region tree\n";
 774 }
 775
 776 #if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
 777 template <class Tr>
 778 void RegionInfoBase<Tr>::dump() const { print(dbgs()); }
 779 #endif
 780
 781 template <class Tr>
 782 void RegionInfoBase<Tr>::releaseMemory() {
 783   BBtoRegion.clear();
 784   if (TopLevelRegion)
 785     delete TopLevelRegion;
 786   TopLevelRegion = nullptr;
 787 }
 788
 789 template <class Tr>
 790 void RegionInfoBase<Tr>::verifyAnalysis() const {
 791   TopLevelRegion->verifyRegionNest();
 792 }
 793
 794 // Region pass manager support.
 795 template <class Tr>
 796 typename Tr::RegionT *RegionInfoBase<Tr>::getRegionFor(BlockT *BB) const {
 797   typename BBtoRegionMap::const_iterator I = BBtoRegion.find(BB);
 798   return I != BBtoRegion.end() ? I->second : nullptr;
 799 }
 800
 801 template <class Tr>
 802 void RegionInfoBase<Tr>::setRegionFor(BlockT *BB, RegionT *R) {
 803   BBtoRegion[BB] = R;
 804 }
 805
 806 template <class Tr>
 807 typename Tr::RegionT *RegionInfoBase<Tr>::operator[](BlockT *BB) const {
 808   return getRegionFor(BB);
 809 }
 810
 811 template <class Tr>
 812 typename RegionInfoBase<Tr>::BlockT *
 813 RegionInfoBase<Tr>::getMaxRegionExit(BlockT *BB) const {
 814   BlockT *Exit = nullptr;
 815
 816   while (true) {
 817     // Get largest region that starts at BB.
 818     RegionT *R = getRegionFor(BB);
 819     while (R && R->getParent() && R->getParent()->getEntry() == BB)
 820       R = R->getParent();
 821
 822     // Get the single exit of BB.
 823     if (R && R->getEntry() == BB)
 824       Exit = R->getExit();
 825     else if (++BlockTraits::child_begin(BB) == BlockTraits::child_end(BB))
 826       Exit = *BlockTraits::child_begin(BB);
 827     else // No single exit exists.
 828       return Exit;
 829
 830     // Get largest region that starts at Exit.
 831     RegionT *ExitR = getRegionFor(Exit);
 832     while (ExitR && ExitR->getParent() &&
 833            ExitR->getParent()->getEntry() == Exit)
 834       ExitR = ExitR->getParent();
 835
 836     for (PredIterTy PI = InvBlockTraits::child_begin(Exit),
 837                     PE = InvBlockTraits::child_end(Exit);
 838          PI != PE; ++PI) {
 839       if (!R->contains(*PI) && !ExitR->contains(*PI))
 840         break;
 841     }
 842
 843     // This stops infinite cycles.
 844     if (DT->dominates(Exit, BB))
 845       break;
 846
 847     BB = Exit;
 848   }
 849
 850   return Exit;
 851 }
 852
 853 template <class Tr>
 854 typename Tr::RegionT *RegionInfoBase<Tr>::getCommonRegion(RegionT *A,
 855                                                           RegionT *B) const {
 856   assert(A && B && "One of the Regions is NULL");
 857
 858   if (A->contains(B))
 859     return A;
 860
 861   while (!B->contains(A))
 862     B = B->getParent();
 863
 864   return B;
 865 }
 866
 867 template <class Tr>
 868 typename Tr::RegionT *
 869 RegionInfoBase<Tr>::getCommonRegion(SmallVectorImpl<RegionT *> &Regions) const {
 870   RegionT *ret = Regions.back();
 871   Regions.pop_back();
 872
 873   for (RegionT *R : Regions)
 874     ret = getCommonRegion(ret, R);
 875
 876   return ret;
 877 }
 878
 879 template <class Tr>
 880 typename Tr::RegionT *
 881 RegionInfoBase<Tr>::getCommonRegion(SmallVectorImpl<BlockT *> &BBs) const {
 882   RegionT *ret = getRegionFor(BBs.back());
 883   BBs.pop_back();
 884
 885   for (BlockT *BB : BBs)
 886     ret = getCommonRegion(ret, getRegionFor(BB));
 887
 888   return ret;
 889 }
 890
 891 template <class Tr>
 892 void RegionInfoBase<Tr>::splitBlock(BlockT *NewBB, BlockT *OldBB) {
 893   RegionT *R = getRegionFor(OldBB);
 894
 895   setRegionFor(NewBB, R);
 896
 897   while (R->getEntry() == OldBB && !R->isTopLevelRegion()) {
 898     R->replaceEntry(NewBB);
 899     R = R->getParent();
 900   }
 901
 902   setRegionFor(OldBB, R);
 903 }
 904
 905 template <class Tr>
 906 void RegionInfoBase<Tr>::calculate(FuncT &F) {
 907   typedef typename std::add_pointer<FuncT>::type FuncPtrT;
 908
 909   // ShortCut a function where for every BB the exit of the largest region
 910   // starting with BB is stored. These regions can be threated as single BBS.
 911   // This improves performance on linear CFGs.
 912   BBtoBBMap ShortCut;
 913
 914   scanForRegions(F, &ShortCut);
 915   BlockT *BB = GraphTraits<FuncPtrT>::getEntryNode(&F);
 916   buildRegionsTree(DT->getNode(BB), TopLevelRegion);
 917 }
 918
 919 #undef DEBUG_TYPE
 920
 921 } // end namespace llvm
 922
 923 #endif