1//===- RegionInfo.cpp - SESE region detection analysis --------------------===// 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#include "llvm/Analysis/RegionInfo.h" 13#include "llvm/Analysis/RegionIterator.h" 14 15#include "llvm/ADT/PostOrderIterator.h" 16#include "llvm/ADT/Statistic.h" 17#include "llvm/Support/CommandLine.h" 18#include "llvm/Support/ErrorHandling.h" 19#include "llvm/Analysis/LoopInfo.h" 20#include "llvm/Assembly/Writer.h" 21 22#define DEBUG_TYPE "region" 23#include "llvm/Support/Debug.h" 24 25#include <set> 26#include <algorithm> 27 28using namespace llvm; 29 30// Always verify if expensive checking is enabled. 31#ifdef XDEBUG 32static bool VerifyRegionInfo = true; 33#else 34static bool VerifyRegionInfo = false; 35#endif 36 37static cl::opt<bool,true> 38VerifyRegionInfoX("verify-region-info", cl::location(VerifyRegionInfo), 39 cl::desc("Verify region info (time consuming)")); 40 41STATISTIC(numRegions, "The # of regions"); 42STATISTIC(numSimpleRegions, "The # of simple regions"); 43 44static cl::opt<enum Region::PrintStyle> printStyle("print-region-style", 45 cl::Hidden, 46 cl::desc("style of printing regions"), 47 cl::values( 48 clEnumValN(Region::PrintNone, "none", "print no details"), 49 clEnumValN(Region::PrintBB, "bb", 50 "print regions in detail with block_iterator"), 51 clEnumValN(Region::PrintRN, "rn", 52 "print regions in detail with element_iterator"), 53 clEnumValEnd)); 54//===----------------------------------------------------------------------===// 55/// Region Implementation 56Region::Region(BasicBlock *Entry, BasicBlock *Exit, RegionInfo* RInfo, 57 DominatorTree *dt, Region *Parent) 58 : RegionNode(Parent, Entry, 1), RI(RInfo), DT(dt), exit(Exit) {} 59 60Region::~Region() { 61 // Free the cached nodes. 62 for (BBNodeMapT::iterator it = BBNodeMap.begin(), 63 ie = BBNodeMap.end(); it != ie; ++it) 64 delete it->second; 65 66 // Only clean the cache for this Region. Caches of child Regions will be 67 // cleaned when the child Regions are deleted. 68 BBNodeMap.clear(); 69 70 for (iterator I = begin(), E = end(); I != E; ++I) 71 delete *I; 72} 73 74void Region::replaceEntry(BasicBlock *BB) { 75 entry.setPointer(BB); 76} 77 78void Region::replaceExit(BasicBlock *BB) { 79 assert(exit && "No exit to replace!"); 80 exit = BB; 81} 82 83bool Region::contains(const BasicBlock *B) const { 84 BasicBlock *BB = const_cast<BasicBlock*>(B); 85 86 assert(DT->getNode(BB) && "BB not part of the dominance tree"); 87 88 BasicBlock *entry = getEntry(), *exit = getExit(); 89 90 // Toplevel region. 91 if (!exit) 92 return true; 93 94 return (DT->dominates(entry, BB) 95 && !(DT->dominates(exit, BB) && DT->dominates(entry, exit))); 96} 97 98bool Region::contains(const Loop *L) const { 99 // BBs that are not part of any loop are element of the Loop 100 // described by the NULL pointer. This loop is not part of any region, 101 // except if the region describes the whole function. 102 if (L == 0) 103 return getExit() == 0; 104 105 if (!contains(L->getHeader())) 106 return false; 107 108 SmallVector<BasicBlock *, 8> ExitingBlocks; 109 L->getExitingBlocks(ExitingBlocks); 110 111 for (SmallVectorImpl<BasicBlock*>::iterator BI = ExitingBlocks.begin(), 112 BE = ExitingBlocks.end(); BI != BE; ++BI) 113 if (!contains(*BI)) 114 return false; 115 116 return true; 117} 118 119Loop *Region::outermostLoopInRegion(Loop *L) const { 120 if (!contains(L)) 121 return 0; 122 123 while (L && contains(L->getParentLoop())) { 124 L = L->getParentLoop(); 125 } 126 127 return L; 128} 129 130Loop *Region::outermostLoopInRegion(LoopInfo *LI, BasicBlock* BB) const { 131 assert(LI && BB && "LI and BB cannot be null!"); 132 Loop *L = LI->getLoopFor(BB); 133 return outermostLoopInRegion(L); 134} 135 136BasicBlock *Region::getEnteringBlock() const { 137 BasicBlock *entry = getEntry(); 138 BasicBlock *Pred; 139 BasicBlock *enteringBlock = 0; 140 141 for (pred_iterator PI = pred_begin(entry), PE = pred_end(entry); PI != PE; 142 ++PI) { 143 Pred = *PI; 144 if (DT->getNode(Pred) && !contains(Pred)) { 145 if (enteringBlock) 146 return 0; 147 148 enteringBlock = Pred; 149 } 150 } 151 152 return enteringBlock; 153} 154 155BasicBlock *Region::getExitingBlock() const { 156 BasicBlock *exit = getExit(); 157 BasicBlock *Pred; 158 BasicBlock *exitingBlock = 0; 159 160 if (!exit) 161 return 0; 162 163 for (pred_iterator PI = pred_begin(exit), PE = pred_end(exit); PI != PE; 164 ++PI) { 165 Pred = *PI; 166 if (contains(Pred)) { 167 if (exitingBlock) 168 return 0; 169 170 exitingBlock = Pred; 171 } 172 } 173 174 return exitingBlock; 175} 176 177bool Region::isSimple() const { 178 return !isTopLevelRegion() && getEnteringBlock() && getExitingBlock(); 179} 180 181std::string Region::getNameStr() const { 182 std::string exitName; 183 std::string entryName; 184 185 if (getEntry()->getName().empty()) { 186 raw_string_ostream OS(entryName); 187 188 WriteAsOperand(OS, getEntry(), false); 189 } else 190 entryName = getEntry()->getName(); 191 192 if (getExit()) { 193 if (getExit()->getName().empty()) { 194 raw_string_ostream OS(exitName); 195 196 WriteAsOperand(OS, getExit(), false); 197 } else 198 exitName = getExit()->getName(); 199 } else 200 exitName = "<Function Return>"; 201 202 return entryName + " => " + exitName; 203} 204 205void Region::verifyBBInRegion(BasicBlock *BB) const { 206 if (!contains(BB)) 207 llvm_unreachable("Broken region found!"); 208 209 BasicBlock *entry = getEntry(), *exit = getExit(); 210 211 for (succ_iterator SI = succ_begin(BB), SE = succ_end(BB); SI != SE; ++SI) 212 if (!contains(*SI) && exit != *SI) 213 llvm_unreachable("Broken region found!"); 214 215 if (entry != BB) 216 for (pred_iterator SI = pred_begin(BB), SE = pred_end(BB); SI != SE; ++SI) 217 if (!contains(*SI)) 218 llvm_unreachable("Broken region found!"); 219} 220 221void Region::verifyWalk(BasicBlock *BB, std::set<BasicBlock*> *visited) const { 222 BasicBlock *exit = getExit(); 223 224 visited->insert(BB); 225 226 verifyBBInRegion(BB); 227 228 for (succ_iterator SI = succ_begin(BB), SE = succ_end(BB); SI != SE; ++SI) 229 if (*SI != exit && visited->find(*SI) == visited->end()) 230 verifyWalk(*SI, visited); 231} 232 233void Region::verifyRegion() const { 234 // Only do verification when user wants to, otherwise this expensive 235 // check will be invoked by PassManager. 236 if (!VerifyRegionInfo) return; 237 238 std::set<BasicBlock*> visited; 239 verifyWalk(getEntry(), &visited); 240} 241 242void Region::verifyRegionNest() const { 243 for (Region::const_iterator RI = begin(), RE = end(); RI != RE; ++RI) 244 (*RI)->verifyRegionNest(); 245 246 verifyRegion(); 247} 248 249Region::element_iterator Region::element_begin() { 250 return GraphTraits<Region*>::nodes_begin(this); 251} 252 253Region::element_iterator Region::element_end() { 254 return GraphTraits<Region*>::nodes_end(this); 255} 256 257Region::const_element_iterator Region::element_begin() const { 258 return GraphTraits<const Region*>::nodes_begin(this); 259} 260 261Region::const_element_iterator Region::element_end() const { 262 return GraphTraits<const Region*>::nodes_end(this); 263} 264 265Region* Region::getSubRegionNode(BasicBlock *BB) const { 266 Region *R = RI->getRegionFor(BB); 267 268 if (!R || R == this) 269 return 0; 270 271 // If we pass the BB out of this region, that means our code is broken. 272 assert(contains(R) && "BB not in current region!"); 273 274 while (contains(R->getParent()) && R->getParent() != this) 275 R = R->getParent(); 276 277 if (R->getEntry() != BB) 278 return 0; 279 280 return R; 281} 282 283RegionNode* Region::getBBNode(BasicBlock *BB) const { 284 assert(contains(BB) && "Can get BB node out of this region!"); 285 286 BBNodeMapT::const_iterator at = BBNodeMap.find(BB); 287 288 if (at != BBNodeMap.end()) 289 return at->second; 290 291 RegionNode *NewNode = new RegionNode(const_cast<Region*>(this), BB); 292 BBNodeMap.insert(std::make_pair(BB, NewNode)); 293 return NewNode; 294} 295 296RegionNode* Region::getNode(BasicBlock *BB) const { 297 assert(contains(BB) && "Can get BB node out of this region!"); 298 if (Region* Child = getSubRegionNode(BB)) 299 return Child->getNode(); 300 301 return getBBNode(BB); 302} 303 304void Region::transferChildrenTo(Region *To) { 305 for (iterator I = begin(), E = end(); I != E; ++I) { 306 (*I)->parent = To; 307 To->children.push_back(*I); 308 } 309 children.clear(); 310} 311 312void Region::addSubRegion(Region *SubRegion, bool moveChildren) { 313 assert(SubRegion->parent == 0 && "SubRegion already has a parent!"); 314 assert(std::find(begin(), end(), SubRegion) == children.end() 315 && "Subregion already exists!"); 316 317 SubRegion->parent = this; 318 children.push_back(SubRegion); 319 320 if (!moveChildren) 321 return; 322 323 assert(SubRegion->children.size() == 0 324 && "SubRegions that contain children are not supported"); 325 326 for (element_iterator I = element_begin(), E = element_end(); I != E; ++I) 327 if (!(*I)->isSubRegion()) { 328 BasicBlock *BB = (*I)->getNodeAs<BasicBlock>(); 329 330 if (SubRegion->contains(BB)) 331 RI->setRegionFor(BB, SubRegion); 332 } 333 334 std::vector<Region*> Keep; 335 for (iterator I = begin(), E = end(); I != E; ++I) 336 if (SubRegion->contains(*I) && *I != SubRegion) { 337 SubRegion->children.push_back(*I); 338 (*I)->parent = SubRegion; 339 } else 340 Keep.push_back(*I); 341 342 children.clear(); 343 children.insert(children.begin(), Keep.begin(), Keep.end()); 344} 345 346 347Region *Region::removeSubRegion(Region *Child) { 348 assert(Child->parent == this && "Child is not a child of this region!"); 349 Child->parent = 0; 350 RegionSet::iterator I = std::find(children.begin(), children.end(), Child); 351 assert(I != children.end() && "Region does not exit. Unable to remove."); 352 children.erase(children.begin()+(I-begin())); 353 return Child; 354} 355 356unsigned Region::getDepth() const { 357 unsigned Depth = 0; 358 359 for (Region *R = parent; R != 0; R = R->parent) 360 ++Depth; 361 362 return Depth; 363} 364 365Region *Region::getExpandedRegion() const { 366 unsigned NumSuccessors = exit->getTerminator()->getNumSuccessors(); 367 368 if (NumSuccessors == 0) 369 return NULL; 370 371 for (pred_iterator PI = pred_begin(getExit()), PE = pred_end(getExit()); 372 PI != PE; ++PI) 373 if (!DT->dominates(getEntry(), *PI)) 374 return NULL; 375 376 Region *R = RI->getRegionFor(exit); 377 378 if (R->getEntry() != exit) { 379 if (exit->getTerminator()->getNumSuccessors() == 1) 380 return new Region(getEntry(), *succ_begin(exit), RI, DT); 381 else 382 return NULL; 383 } 384 385 while (R->getParent() && R->getParent()->getEntry() == exit) 386 R = R->getParent(); 387 388 if (!DT->dominates(getEntry(), R->getExit())) 389 for (pred_iterator PI = pred_begin(getExit()), PE = pred_end(getExit()); 390 PI != PE; ++PI) 391 if (!DT->dominates(R->getExit(), *PI)) 392 return NULL; 393 394 return new Region(getEntry(), R->getExit(), RI, DT); 395} 396 397void Region::print(raw_ostream &OS, bool print_tree, unsigned level, 398 enum PrintStyle Style) const { 399 if (print_tree) 400 OS.indent(level*2) << "[" << level << "] " << getNameStr(); 401 else 402 OS.indent(level*2) << getNameStr(); 403 404 OS << "\n"; 405 406 407 if (Style != PrintNone) { 408 OS.indent(level*2) << "{\n"; 409 OS.indent(level*2 + 2); 410 411 if (Style == PrintBB) { 412 for (const_block_iterator I = block_begin(), E = block_end(); I != E; ++I) 413 OS << (*I)->getName() << ", "; // TODO: remove the last "," 414 } else if (Style == PrintRN) { 415 for (const_element_iterator I = element_begin(), E = element_end(); I!=E; ++I) 416 OS << **I << ", "; // TODO: remove the last ", 417 } 418 419 OS << "\n"; 420 } 421 422 if (print_tree) 423 for (const_iterator RI = begin(), RE = end(); RI != RE; ++RI) 424 (*RI)->print(OS, print_tree, level+1, Style); 425 426 if (Style != PrintNone) 427 OS.indent(level*2) << "} \n"; 428} 429 430#ifndef NDEBUG 431void Region::dump() const { 432 print(dbgs(), true, getDepth(), printStyle.getValue()); 433} 434#endif 435 436void Region::clearNodeCache() { 437 // Free the cached nodes. 438 for (BBNodeMapT::iterator I = BBNodeMap.begin(), 439 IE = BBNodeMap.end(); I != IE; ++I) 440 delete I->second; 441 442 BBNodeMap.clear(); 443 for (Region::iterator RI = begin(), RE = end(); RI != RE; ++RI) 444 (*RI)->clearNodeCache(); 445} 446 447//===----------------------------------------------------------------------===// 448// RegionInfo implementation 449// 450 451bool RegionInfo::isCommonDomFrontier(BasicBlock *BB, BasicBlock *entry, 452 BasicBlock *exit) const { 453 for (pred_iterator PI = pred_begin(BB), PE = pred_end(BB); PI != PE; ++PI) { 454 BasicBlock *P = *PI; 455 if (DT->dominates(entry, P) && !DT->dominates(exit, P)) 456 return false; 457 } 458 return true; 459} 460 461bool RegionInfo::isRegion(BasicBlock *entry, BasicBlock *exit) const { 462 assert(entry && exit && "entry and exit must not be null!"); 463 typedef DominanceFrontier::DomSetType DST; 464 465 DST *entrySuccs = &DF->find(entry)->second; 466 467 // Exit is the header of a loop that contains the entry. In this case, 468 // the dominance frontier must only contain the exit. 469 if (!DT->dominates(entry, exit)) { 470 for (DST::iterator SI = entrySuccs->begin(), SE = entrySuccs->end(); 471 SI != SE; ++SI) 472 if (*SI != exit && *SI != entry) 473 return false; 474 475 return true; 476 } 477 478 DST *exitSuccs = &DF->find(exit)->second; 479 480 // Do not allow edges leaving the region. 481 for (DST::iterator SI = entrySuccs->begin(), SE = entrySuccs->end(); 482 SI != SE; ++SI) { 483 if (*SI == exit || *SI == entry) 484 continue; 485 if (exitSuccs->find(*SI) == exitSuccs->end()) 486 return false; 487 if (!isCommonDomFrontier(*SI, entry, exit)) 488 return false; 489 } 490 491 // Do not allow edges pointing into the region. 492 for (DST::iterator SI = exitSuccs->begin(), SE = exitSuccs->end(); 493 SI != SE; ++SI) 494 if (DT->properlyDominates(entry, *SI) && *SI != exit) 495 return false; 496 497 498 return true; 499} 500 501void RegionInfo::insertShortCut(BasicBlock *entry, BasicBlock *exit, 502 BBtoBBMap *ShortCut) const { 503 assert(entry && exit && "entry and exit must not be null!"); 504 505 BBtoBBMap::iterator e = ShortCut->find(exit); 506 507 if (e == ShortCut->end()) 508 // No further region at exit available. 509 (*ShortCut)[entry] = exit; 510 else { 511 // We found a region e that starts at exit. Therefore (entry, e->second) 512 // is also a region, that is larger than (entry, exit). Insert the 513 // larger one. 514 BasicBlock *BB = e->second; 515 (*ShortCut)[entry] = BB; 516 } 517} 518 519DomTreeNode* RegionInfo::getNextPostDom(DomTreeNode* N, 520 BBtoBBMap *ShortCut) const { 521 BBtoBBMap::iterator e = ShortCut->find(N->getBlock()); 522 523 if (e == ShortCut->end()) 524 return N->getIDom(); 525 526 return PDT->getNode(e->second)->getIDom(); 527} 528 529bool RegionInfo::isTrivialRegion(BasicBlock *entry, BasicBlock *exit) const { 530 assert(entry && exit && "entry and exit must not be null!"); 531 532 unsigned num_successors = succ_end(entry) - succ_begin(entry); 533 534 if (num_successors <= 1 && exit == *(succ_begin(entry))) 535 return true; 536 537 return false; 538} 539 540void RegionInfo::updateStatistics(Region *R) { 541 ++numRegions; 542 543 // TODO: Slow. Should only be enabled if -stats is used. 544 if (R->isSimple()) ++numSimpleRegions; 545} 546 547Region *RegionInfo::createRegion(BasicBlock *entry, BasicBlock *exit) { 548 assert(entry && exit && "entry and exit must not be null!"); 549 550 if (isTrivialRegion(entry, exit)) 551 return 0; 552 553 Region *region = new Region(entry, exit, this, DT); 554 BBtoRegion.insert(std::make_pair(entry, region)); 555 556 #ifdef XDEBUG 557 region->verifyRegion(); 558 #else 559 DEBUG(region->verifyRegion()); 560 #endif 561 562 updateStatistics(region); 563 return region; 564} 565 566void RegionInfo::findRegionsWithEntry(BasicBlock *entry, BBtoBBMap *ShortCut) { 567 assert(entry); 568 569 DomTreeNode *N = PDT->getNode(entry); 570 571 if (!N) 572 return; 573 574 Region *lastRegion= 0; 575 BasicBlock *lastExit = entry; 576 577 // As only a BasicBlock that postdominates entry can finish a region, walk the 578 // post dominance tree upwards. 579 while ((N = getNextPostDom(N, ShortCut))) { 580 BasicBlock *exit = N->getBlock(); 581 582 if (!exit) 583 break; 584 585 if (isRegion(entry, exit)) { 586 Region *newRegion = createRegion(entry, exit); 587 588 if (lastRegion) 589 newRegion->addSubRegion(lastRegion); 590 591 lastRegion = newRegion; 592 lastExit = exit; 593 } 594 595 // This can never be a region, so stop the search. 596 if (!DT->dominates(entry, exit)) 597 break; 598 } 599 600 // Tried to create regions from entry to lastExit. Next time take a 601 // shortcut from entry to lastExit. 602 if (lastExit != entry) 603 insertShortCut(entry, lastExit, ShortCut); 604} 605 606void RegionInfo::scanForRegions(Function &F, BBtoBBMap *ShortCut) { 607 BasicBlock *entry = &(F.getEntryBlock()); 608 DomTreeNode *N = DT->getNode(entry); 609 610 // Iterate over the dominance tree in post order to start with the small 611 // regions from the bottom of the dominance tree. If the small regions are 612 // detected first, detection of bigger regions is faster, as we can jump 613 // over the small regions. 614 for (po_iterator<DomTreeNode*> FI = po_begin(N), FE = po_end(N); FI != FE; 615 ++FI) { 616 findRegionsWithEntry(FI->getBlock(), ShortCut); 617 } 618} 619 620Region *RegionInfo::getTopMostParent(Region *region) { 621 while (region->parent) 622 region = region->getParent(); 623 624 return region; 625} 626 627void RegionInfo::buildRegionsTree(DomTreeNode *N, Region *region) { 628 BasicBlock *BB = N->getBlock(); 629 630 // Passed region exit 631 while (BB == region->getExit()) 632 region = region->getParent(); 633 634 BBtoRegionMap::iterator it = BBtoRegion.find(BB); 635 636 // This basic block is a start block of a region. It is already in the 637 // BBtoRegion relation. Only the child basic blocks have to be updated. 638 if (it != BBtoRegion.end()) { 639 Region *newRegion = it->second; 640 region->addSubRegion(getTopMostParent(newRegion)); 641 region = newRegion; 642 } else { 643 BBtoRegion[BB] = region; 644 } 645 646 for (DomTreeNode::iterator CI = N->begin(), CE = N->end(); CI != CE; ++CI) 647 buildRegionsTree(*CI, region); 648} 649 650void RegionInfo::releaseMemory() { 651 BBtoRegion.clear(); 652 if (TopLevelRegion) 653 delete TopLevelRegion; 654 TopLevelRegion = 0; 655} 656 657RegionInfo::RegionInfo() : FunctionPass(ID) { 658 initializeRegionInfoPass(*PassRegistry::getPassRegistry()); 659 TopLevelRegion = 0; 660} 661 662RegionInfo::~RegionInfo() { 663 releaseMemory(); 664} 665 666void RegionInfo::Calculate(Function &F) { 667 // ShortCut a function where for every BB the exit of the largest region 668 // starting with BB is stored. These regions can be threated as single BBS. 669 // This improves performance on linear CFGs. 670 BBtoBBMap ShortCut; 671 672 scanForRegions(F, &ShortCut); 673 BasicBlock *BB = &F.getEntryBlock(); 674 buildRegionsTree(DT->getNode(BB), TopLevelRegion); 675} 676 677bool RegionInfo::runOnFunction(Function &F) { 678 releaseMemory(); 679 680 DT = &getAnalysis<DominatorTree>(); 681 PDT = &getAnalysis<PostDominatorTree>(); 682 DF = &getAnalysis<DominanceFrontier>(); 683 684 TopLevelRegion = new Region(&F.getEntryBlock(), 0, this, DT, 0); 685 updateStatistics(TopLevelRegion); 686 687 Calculate(F); 688 689 return false; 690} 691 692void RegionInfo::getAnalysisUsage(AnalysisUsage &AU) const { 693 AU.setPreservesAll(); 694 AU.addRequiredTransitive<DominatorTree>(); 695 AU.addRequired<PostDominatorTree>(); 696 AU.addRequired<DominanceFrontier>(); 697} 698 699void RegionInfo::print(raw_ostream &OS, const Module *) const { 700 OS << "Region tree:\n"; 701 TopLevelRegion->print(OS, true, 0, printStyle.getValue()); 702 OS << "End region tree\n"; 703} 704 705void RegionInfo::verifyAnalysis() const { 706 // Only do verification when user wants to, otherwise this expensive check 707 // will be invoked by PMDataManager::verifyPreservedAnalysis when 708 // a regionpass (marked PreservedAll) finish. 709 if (!VerifyRegionInfo) return; 710 711 TopLevelRegion->verifyRegionNest(); 712} 713 714// Region pass manager support. 715Region *RegionInfo::getRegionFor(BasicBlock *BB) const { 716 BBtoRegionMap::const_iterator I= 717 BBtoRegion.find(BB); 718 return I != BBtoRegion.end() ? I->second : 0; 719} 720 721void RegionInfo::setRegionFor(BasicBlock *BB, Region *R) { 722 BBtoRegion[BB] = R; 723} 724 725Region *RegionInfo::operator[](BasicBlock *BB) const { 726 return getRegionFor(BB); 727} 728 729BasicBlock *RegionInfo::getMaxRegionExit(BasicBlock *BB) const { 730 BasicBlock *Exit = NULL; 731 732 while (true) { 733 // Get largest region that starts at BB. 734 Region *R = getRegionFor(BB); 735 while (R && R->getParent() && R->getParent()->getEntry() == BB) 736 R = R->getParent(); 737 738 // Get the single exit of BB. 739 if (R && R->getEntry() == BB) 740 Exit = R->getExit(); 741 else if (++succ_begin(BB) == succ_end(BB)) 742 Exit = *succ_begin(BB); 743 else // No single exit exists. 744 return Exit; 745 746 // Get largest region that starts at Exit. 747 Region *ExitR = getRegionFor(Exit); 748 while (ExitR && ExitR->getParent() 749 && ExitR->getParent()->getEntry() == Exit) 750 ExitR = ExitR->getParent(); 751 752 for (pred_iterator PI = pred_begin(Exit), PE = pred_end(Exit); PI != PE; 753 ++PI) 754 if (!R->contains(*PI) && !ExitR->contains(*PI)) 755 break; 756 757 // This stops infinite cycles. 758 if (DT->dominates(Exit, BB)) 759 break; 760 761 BB = Exit; 762 } 763 764 return Exit; 765} 766 767Region* 768RegionInfo::getCommonRegion(Region *A, Region *B) const { 769 assert (A && B && "One of the Regions is NULL"); 770 771 if (A->contains(B)) return A; 772 773 while (!B->contains(A)) 774 B = B->getParent(); 775 776 return B; 777} 778 779Region* 780RegionInfo::getCommonRegion(SmallVectorImpl<Region*> &Regions) const { 781 Region* ret = Regions.back(); 782 Regions.pop_back(); 783 784 for (SmallVectorImpl<Region*>::const_iterator I = Regions.begin(), 785 E = Regions.end(); I != E; ++I) 786 ret = getCommonRegion(ret, *I); 787 788 return ret; 789} 790 791Region* 792RegionInfo::getCommonRegion(SmallVectorImpl<BasicBlock*> &BBs) const { 793 Region* ret = getRegionFor(BBs.back()); 794 BBs.pop_back(); 795 796 for (SmallVectorImpl<BasicBlock*>::const_iterator I = BBs.begin(), 797 E = BBs.end(); I != E; ++I) 798 ret = getCommonRegion(ret, getRegionFor(*I)); 799 800 return ret; 801} 802 803void RegionInfo::splitBlock(BasicBlock* NewBB, BasicBlock *OldBB) 804{ 805 Region *R = getRegionFor(OldBB); 806 807 setRegionFor(NewBB, R); 808 809 while (R->getEntry() == OldBB && !R->isTopLevelRegion()) { 810 R->replaceEntry(NewBB); 811 R = R->getParent(); 812 } 813 814 setRegionFor(OldBB, R); 815} 816 817char RegionInfo::ID = 0; 818INITIALIZE_PASS_BEGIN(RegionInfo, "regions", 819 "Detect single entry single exit regions", true, true) 820INITIALIZE_PASS_DEPENDENCY(DominatorTree) 821INITIALIZE_PASS_DEPENDENCY(PostDominatorTree) 822INITIALIZE_PASS_DEPENDENCY(DominanceFrontier) 823INITIALIZE_PASS_END(RegionInfo, "regions", 824 "Detect single entry single exit regions", true, true) 825 826// Create methods available outside of this file, to use them 827// "include/llvm/LinkAllPasses.h". Otherwise the pass would be deleted by 828// the link time optimization. 829 830namespace llvm { 831 FunctionPass *createRegionInfoPass() { 832 return new RegionInfo(); 833 } 834} 835 836