Dominators.h revision 25ac7518ffda5f4256e8333dde4801270bb26418
1//===- llvm/Analysis/Dominators.h - Dominator Info Calculation --*- 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// 10// This file defines the DominatorTree class, which provides fast and efficient 11// dominance queries. 12// 13//===----------------------------------------------------------------------===// 14 15#ifndef LLVM_ANALYSIS_DOMINATORS_H 16#define LLVM_ANALYSIS_DOMINATORS_H 17 18#include "llvm/Pass.h" 19#include "llvm/Function.h" 20#include "llvm/ADT/DenseMap.h" 21#include "llvm/ADT/DepthFirstIterator.h" 22#include "llvm/ADT/GraphTraits.h" 23#include "llvm/ADT/SmallPtrSet.h" 24#include "llvm/ADT/SmallVector.h" 25#include "llvm/Support/CFG.h" 26#include "llvm/Support/Compiler.h" 27#include "llvm/Support/raw_ostream.h" 28#include <algorithm> 29 30namespace llvm { 31 32//===----------------------------------------------------------------------===// 33/// DominatorBase - Base class that other, more interesting dominator analyses 34/// inherit from. 35/// 36template <class NodeT> 37class DominatorBase { 38protected: 39 std::vector<NodeT*> Roots; 40 const bool IsPostDominators; 41 inline explicit DominatorBase(bool isPostDom) : 42 Roots(), IsPostDominators(isPostDom) {} 43public: 44 45 /// getRoots - Return the root blocks of the current CFG. This may include 46 /// multiple blocks if we are computing post dominators. For forward 47 /// dominators, this will always be a single block (the entry node). 48 /// 49 inline const std::vector<NodeT*> &getRoots() const { return Roots; } 50 51 /// isPostDominator - Returns true if analysis based of postdoms 52 /// 53 bool isPostDominator() const { return IsPostDominators; } 54}; 55 56 57//===----------------------------------------------------------------------===// 58// DomTreeNode - Dominator Tree Node 59template<class NodeT> class DominatorTreeBase; 60struct PostDominatorTree; 61class MachineBasicBlock; 62 63template <class NodeT> 64class DomTreeNodeBase { 65 NodeT *TheBB; 66 DomTreeNodeBase<NodeT> *IDom; 67 std::vector<DomTreeNodeBase<NodeT> *> Children; 68 int DFSNumIn, DFSNumOut; 69 70 template<class N> friend class DominatorTreeBase; 71 friend struct PostDominatorTree; 72public: 73 typedef typename std::vector<DomTreeNodeBase<NodeT> *>::iterator iterator; 74 typedef typename std::vector<DomTreeNodeBase<NodeT> *>::const_iterator 75 const_iterator; 76 77 iterator begin() { return Children.begin(); } 78 iterator end() { return Children.end(); } 79 const_iterator begin() const { return Children.begin(); } 80 const_iterator end() const { return Children.end(); } 81 82 NodeT *getBlock() const { return TheBB; } 83 DomTreeNodeBase<NodeT> *getIDom() const { return IDom; } 84 const std::vector<DomTreeNodeBase<NodeT>*> &getChildren() const { 85 return Children; 86 } 87 88 DomTreeNodeBase(NodeT *BB, DomTreeNodeBase<NodeT> *iDom) 89 : TheBB(BB), IDom(iDom), DFSNumIn(-1), DFSNumOut(-1) { } 90 91 DomTreeNodeBase<NodeT> *addChild(DomTreeNodeBase<NodeT> *C) { 92 Children.push_back(C); 93 return C; 94 } 95 96 size_t getNumChildren() const { 97 return Children.size(); 98 } 99 100 void clearAllChildren() { 101 Children.clear(); 102 } 103 104 bool compare(DomTreeNodeBase<NodeT> *Other) { 105 if (getNumChildren() != Other->getNumChildren()) 106 return true; 107 108 SmallPtrSet<NodeT *, 4> OtherChildren; 109 for (iterator I = Other->begin(), E = Other->end(); I != E; ++I) { 110 NodeT *Nd = (*I)->getBlock(); 111 OtherChildren.insert(Nd); 112 } 113 114 for (iterator I = begin(), E = end(); I != E; ++I) { 115 NodeT *N = (*I)->getBlock(); 116 if (OtherChildren.count(N) == 0) 117 return true; 118 } 119 return false; 120 } 121 122 void setIDom(DomTreeNodeBase<NodeT> *NewIDom) { 123 assert(IDom && "No immediate dominator?"); 124 if (IDom != NewIDom) { 125 typename std::vector<DomTreeNodeBase<NodeT>*>::iterator I = 126 std::find(IDom->Children.begin(), IDom->Children.end(), this); 127 assert(I != IDom->Children.end() && 128 "Not in immediate dominator children set!"); 129 // I am no longer your child... 130 IDom->Children.erase(I); 131 132 // Switch to new dominator 133 IDom = NewIDom; 134 IDom->Children.push_back(this); 135 } 136 } 137 138 /// getDFSNumIn/getDFSNumOut - These are an internal implementation detail, do 139 /// not call them. 140 unsigned getDFSNumIn() const { return DFSNumIn; } 141 unsigned getDFSNumOut() const { return DFSNumOut; } 142private: 143 // Return true if this node is dominated by other. Use this only if DFS info 144 // is valid. 145 bool DominatedBy(const DomTreeNodeBase<NodeT> *other) const { 146 return this->DFSNumIn >= other->DFSNumIn && 147 this->DFSNumOut <= other->DFSNumOut; 148 } 149}; 150 151EXTERN_TEMPLATE_INSTANTIATION(class DomTreeNodeBase<BasicBlock>); 152EXTERN_TEMPLATE_INSTANTIATION(class DomTreeNodeBase<MachineBasicBlock>); 153 154template<class NodeT> 155inline raw_ostream &operator<<(raw_ostream &o, 156 const DomTreeNodeBase<NodeT> *Node) { 157 if (Node->getBlock()) 158 WriteAsOperand(o, Node->getBlock(), false); 159 else 160 o << " <<exit node>>"; 161 162 o << " {" << Node->getDFSNumIn() << "," << Node->getDFSNumOut() << "}"; 163 164 return o << "\n"; 165} 166 167template<class NodeT> 168inline void PrintDomTree(const DomTreeNodeBase<NodeT> *N, raw_ostream &o, 169 unsigned Lev) { 170 o.indent(2*Lev) << "[" << Lev << "] " << N; 171 for (typename DomTreeNodeBase<NodeT>::const_iterator I = N->begin(), 172 E = N->end(); I != E; ++I) 173 PrintDomTree<NodeT>(*I, o, Lev+1); 174} 175 176typedef DomTreeNodeBase<BasicBlock> DomTreeNode; 177 178//===----------------------------------------------------------------------===// 179/// DominatorTree - Calculate the immediate dominator tree for a function. 180/// 181 182template<class FuncT, class N> 183void Calculate(DominatorTreeBase<typename GraphTraits<N>::NodeType>& DT, 184 FuncT& F); 185 186template<class NodeT> 187class DominatorTreeBase : public DominatorBase<NodeT> { 188 bool dominatedBySlowTreeWalk(const DomTreeNodeBase<NodeT> *A, 189 const DomTreeNodeBase<NodeT> *B) const { 190 assert(A != B); 191 assert(isReachableFromEntry(B)); 192 assert(isReachableFromEntry(A)); 193 194 const DomTreeNodeBase<NodeT> *IDom; 195 while ((IDom = B->getIDom()) != 0 && IDom != A && IDom != B) 196 B = IDom; // Walk up the tree 197 return IDom != 0; 198 } 199 200protected: 201 typedef DenseMap<NodeT*, DomTreeNodeBase<NodeT>*> DomTreeNodeMapType; 202 DomTreeNodeMapType DomTreeNodes; 203 DomTreeNodeBase<NodeT> *RootNode; 204 205 bool DFSInfoValid; 206 unsigned int SlowQueries; 207 // Information record used during immediate dominators computation. 208 struct InfoRec { 209 unsigned DFSNum; 210 unsigned Parent; 211 unsigned Semi; 212 NodeT *Label; 213 214 InfoRec() : DFSNum(0), Parent(0), Semi(0), Label(0) {} 215 }; 216 217 DenseMap<NodeT*, NodeT*> IDoms; 218 219 // Vertex - Map the DFS number to the BasicBlock* 220 std::vector<NodeT*> Vertex; 221 222 // Info - Collection of information used during the computation of idoms. 223 DenseMap<NodeT*, InfoRec> Info; 224 225 void reset() { 226 for (typename DomTreeNodeMapType::iterator I = this->DomTreeNodes.begin(), 227 E = DomTreeNodes.end(); I != E; ++I) 228 delete I->second; 229 DomTreeNodes.clear(); 230 IDoms.clear(); 231 this->Roots.clear(); 232 Vertex.clear(); 233 RootNode = 0; 234 } 235 236 // NewBB is split and now it has one successor. Update dominator tree to 237 // reflect this change. 238 template<class N, class GraphT> 239 void Split(DominatorTreeBase<typename GraphT::NodeType>& DT, 240 typename GraphT::NodeType* NewBB) { 241 assert(std::distance(GraphT::child_begin(NewBB), 242 GraphT::child_end(NewBB)) == 1 && 243 "NewBB should have a single successor!"); 244 typename GraphT::NodeType* NewBBSucc = *GraphT::child_begin(NewBB); 245 246 std::vector<typename GraphT::NodeType*> PredBlocks; 247 typedef GraphTraits<Inverse<N> > InvTraits; 248 for (typename InvTraits::ChildIteratorType PI = 249 InvTraits::child_begin(NewBB), 250 PE = InvTraits::child_end(NewBB); PI != PE; ++PI) 251 PredBlocks.push_back(*PI); 252 253 assert(!PredBlocks.empty() && "No predblocks?"); 254 255 bool NewBBDominatesNewBBSucc = true; 256 for (typename InvTraits::ChildIteratorType PI = 257 InvTraits::child_begin(NewBBSucc), 258 E = InvTraits::child_end(NewBBSucc); PI != E; ++PI) { 259 typename InvTraits::NodeType *ND = *PI; 260 if (ND != NewBB && !DT.dominates(NewBBSucc, ND) && 261 DT.isReachableFromEntry(ND)) { 262 NewBBDominatesNewBBSucc = false; 263 break; 264 } 265 } 266 267 // Find NewBB's immediate dominator and create new dominator tree node for 268 // NewBB. 269 NodeT *NewBBIDom = 0; 270 unsigned i = 0; 271 for (i = 0; i < PredBlocks.size(); ++i) 272 if (DT.isReachableFromEntry(PredBlocks[i])) { 273 NewBBIDom = PredBlocks[i]; 274 break; 275 } 276 277 // It's possible that none of the predecessors of NewBB are reachable; 278 // in that case, NewBB itself is unreachable, so nothing needs to be 279 // changed. 280 if (!NewBBIDom) 281 return; 282 283 for (i = i + 1; i < PredBlocks.size(); ++i) { 284 if (DT.isReachableFromEntry(PredBlocks[i])) 285 NewBBIDom = DT.findNearestCommonDominator(NewBBIDom, PredBlocks[i]); 286 } 287 288 // Create the new dominator tree node... and set the idom of NewBB. 289 DomTreeNodeBase<NodeT> *NewBBNode = DT.addNewBlock(NewBB, NewBBIDom); 290 291 // If NewBB strictly dominates other blocks, then it is now the immediate 292 // dominator of NewBBSucc. Update the dominator tree as appropriate. 293 if (NewBBDominatesNewBBSucc) { 294 DomTreeNodeBase<NodeT> *NewBBSuccNode = DT.getNode(NewBBSucc); 295 DT.changeImmediateDominator(NewBBSuccNode, NewBBNode); 296 } 297 } 298 299public: 300 explicit DominatorTreeBase(bool isPostDom) 301 : DominatorBase<NodeT>(isPostDom), DFSInfoValid(false), SlowQueries(0) {} 302 virtual ~DominatorTreeBase() { reset(); } 303 304 /// compare - Return false if the other dominator tree base matches this 305 /// dominator tree base. Otherwise return true. 306 bool compare(DominatorTreeBase &Other) const { 307 308 const DomTreeNodeMapType &OtherDomTreeNodes = Other.DomTreeNodes; 309 if (DomTreeNodes.size() != OtherDomTreeNodes.size()) 310 return true; 311 312 for (typename DomTreeNodeMapType::const_iterator 313 I = this->DomTreeNodes.begin(), 314 E = this->DomTreeNodes.end(); I != E; ++I) { 315 NodeT *BB = I->first; 316 typename DomTreeNodeMapType::const_iterator OI = OtherDomTreeNodes.find(BB); 317 if (OI == OtherDomTreeNodes.end()) 318 return true; 319 320 DomTreeNodeBase<NodeT>* MyNd = I->second; 321 DomTreeNodeBase<NodeT>* OtherNd = OI->second; 322 323 if (MyNd->compare(OtherNd)) 324 return true; 325 } 326 327 return false; 328 } 329 330 virtual void releaseMemory() { reset(); } 331 332 /// getNode - return the (Post)DominatorTree node for the specified basic 333 /// block. This is the same as using operator[] on this class. 334 /// 335 inline DomTreeNodeBase<NodeT> *getNode(NodeT *BB) const { 336 return DomTreeNodes.lookup(BB); 337 } 338 339 /// getRootNode - This returns the entry node for the CFG of the function. If 340 /// this tree represents the post-dominance relations for a function, however, 341 /// this root may be a node with the block == NULL. This is the case when 342 /// there are multiple exit nodes from a particular function. Consumers of 343 /// post-dominance information must be capable of dealing with this 344 /// possibility. 345 /// 346 DomTreeNodeBase<NodeT> *getRootNode() { return RootNode; } 347 const DomTreeNodeBase<NodeT> *getRootNode() const { return RootNode; } 348 349 /// properlyDominates - Returns true iff this dominates N and this != N. 350 /// Note that this is not a constant time operation! 351 /// 352 bool properlyDominates(const DomTreeNodeBase<NodeT> *A, 353 const DomTreeNodeBase<NodeT> *B) { 354 if (A == 0 || B == 0) 355 return false; 356 if (A == B) 357 return false; 358 return dominates(A, B); 359 } 360 361 bool properlyDominates(const NodeT *A, const NodeT *B); 362 363 /// isReachableFromEntry - Return true if A is dominated by the entry 364 /// block of the function containing it. 365 bool isReachableFromEntry(const NodeT* A) const { 366 assert(!this->isPostDominator() && 367 "This is not implemented for post dominators"); 368 return isReachableFromEntry(getNode(const_cast<NodeT *>(A))); 369 } 370 371 inline bool isReachableFromEntry(const DomTreeNodeBase<NodeT> *A) const { 372 return A; 373 } 374 375 /// dominates - Returns true iff A dominates B. Note that this is not a 376 /// constant time operation! 377 /// 378 inline bool dominates(const DomTreeNodeBase<NodeT> *A, 379 const DomTreeNodeBase<NodeT> *B) { 380 // A node trivially dominates itself. 381 if (B == A) 382 return true; 383 384 // An unreachable node is dominated by anything. 385 if (!isReachableFromEntry(B)) 386 return true; 387 388 // And dominates nothing. 389 if (!isReachableFromEntry(A)) 390 return false; 391 392 // Compare the result of the tree walk and the dfs numbers, if expensive 393 // checks are enabled. 394#ifdef XDEBUG 395 assert((!DFSInfoValid || 396 (dominatedBySlowTreeWalk(A, B) == B->DominatedBy(A))) && 397 "Tree walk disagrees with dfs numbers!"); 398#endif 399 400 if (DFSInfoValid) 401 return B->DominatedBy(A); 402 403 // If we end up with too many slow queries, just update the 404 // DFS numbers on the theory that we are going to keep querying. 405 SlowQueries++; 406 if (SlowQueries > 32) { 407 updateDFSNumbers(); 408 return B->DominatedBy(A); 409 } 410 411 return dominatedBySlowTreeWalk(A, B); 412 } 413 414 bool dominates(const NodeT *A, const NodeT *B); 415 416 NodeT *getRoot() const { 417 assert(this->Roots.size() == 1 && "Should always have entry node!"); 418 return this->Roots[0]; 419 } 420 421 /// findNearestCommonDominator - Find nearest common dominator basic block 422 /// for basic block A and B. If there is no such block then return NULL. 423 NodeT *findNearestCommonDominator(NodeT *A, NodeT *B) { 424 assert(A->getParent() == B->getParent() && 425 "Two blocks are not in same function"); 426 427 // If either A or B is a entry block then it is nearest common dominator 428 // (for forward-dominators). 429 if (!this->isPostDominator()) { 430 NodeT &Entry = A->getParent()->front(); 431 if (A == &Entry || B == &Entry) 432 return &Entry; 433 } 434 435 // If B dominates A then B is nearest common dominator. 436 if (dominates(B, A)) 437 return B; 438 439 // If A dominates B then A is nearest common dominator. 440 if (dominates(A, B)) 441 return A; 442 443 DomTreeNodeBase<NodeT> *NodeA = getNode(A); 444 DomTreeNodeBase<NodeT> *NodeB = getNode(B); 445 446 // Collect NodeA dominators set. 447 SmallPtrSet<DomTreeNodeBase<NodeT>*, 16> NodeADoms; 448 NodeADoms.insert(NodeA); 449 DomTreeNodeBase<NodeT> *IDomA = NodeA->getIDom(); 450 while (IDomA) { 451 NodeADoms.insert(IDomA); 452 IDomA = IDomA->getIDom(); 453 } 454 455 // Walk NodeB immediate dominators chain and find common dominator node. 456 DomTreeNodeBase<NodeT> *IDomB = NodeB->getIDom(); 457 while (IDomB) { 458 if (NodeADoms.count(IDomB) != 0) 459 return IDomB->getBlock(); 460 461 IDomB = IDomB->getIDom(); 462 } 463 464 return NULL; 465 } 466 467 const NodeT *findNearestCommonDominator(const NodeT *A, const NodeT *B) { 468 // Cast away the const qualifiers here. This is ok since 469 // const is re-introduced on the return type. 470 return findNearestCommonDominator(const_cast<NodeT *>(A), 471 const_cast<NodeT *>(B)); 472 } 473 474 //===--------------------------------------------------------------------===// 475 // API to update (Post)DominatorTree information based on modifications to 476 // the CFG... 477 478 /// addNewBlock - Add a new node to the dominator tree information. This 479 /// creates a new node as a child of DomBB dominator node,linking it into 480 /// the children list of the immediate dominator. 481 DomTreeNodeBase<NodeT> *addNewBlock(NodeT *BB, NodeT *DomBB) { 482 assert(getNode(BB) == 0 && "Block already in dominator tree!"); 483 DomTreeNodeBase<NodeT> *IDomNode = getNode(DomBB); 484 assert(IDomNode && "Not immediate dominator specified for block!"); 485 DFSInfoValid = false; 486 return DomTreeNodes[BB] = 487 IDomNode->addChild(new DomTreeNodeBase<NodeT>(BB, IDomNode)); 488 } 489 490 /// changeImmediateDominator - This method is used to update the dominator 491 /// tree information when a node's immediate dominator changes. 492 /// 493 void changeImmediateDominator(DomTreeNodeBase<NodeT> *N, 494 DomTreeNodeBase<NodeT> *NewIDom) { 495 assert(N && NewIDom && "Cannot change null node pointers!"); 496 DFSInfoValid = false; 497 N->setIDom(NewIDom); 498 } 499 500 void changeImmediateDominator(NodeT *BB, NodeT *NewBB) { 501 changeImmediateDominator(getNode(BB), getNode(NewBB)); 502 } 503 504 /// eraseNode - Removes a node from the dominator tree. Block must not 505 /// dominate any other blocks. Removes node from its immediate dominator's 506 /// children list. Deletes dominator node associated with basic block BB. 507 void eraseNode(NodeT *BB) { 508 DomTreeNodeBase<NodeT> *Node = getNode(BB); 509 assert(Node && "Removing node that isn't in dominator tree."); 510 assert(Node->getChildren().empty() && "Node is not a leaf node."); 511 512 // Remove node from immediate dominator's children list. 513 DomTreeNodeBase<NodeT> *IDom = Node->getIDom(); 514 if (IDom) { 515 typename std::vector<DomTreeNodeBase<NodeT>*>::iterator I = 516 std::find(IDom->Children.begin(), IDom->Children.end(), Node); 517 assert(I != IDom->Children.end() && 518 "Not in immediate dominator children set!"); 519 // I am no longer your child... 520 IDom->Children.erase(I); 521 } 522 523 DomTreeNodes.erase(BB); 524 delete Node; 525 } 526 527 /// removeNode - Removes a node from the dominator tree. Block must not 528 /// dominate any other blocks. Invalidates any node pointing to removed 529 /// block. 530 void removeNode(NodeT *BB) { 531 assert(getNode(BB) && "Removing node that isn't in dominator tree."); 532 DomTreeNodes.erase(BB); 533 } 534 535 /// splitBlock - BB is split and now it has one successor. Update dominator 536 /// tree to reflect this change. 537 void splitBlock(NodeT* NewBB) { 538 if (this->IsPostDominators) 539 this->Split<Inverse<NodeT*>, GraphTraits<Inverse<NodeT*> > >(*this, NewBB); 540 else 541 this->Split<NodeT*, GraphTraits<NodeT*> >(*this, NewBB); 542 } 543 544 /// print - Convert to human readable form 545 /// 546 void print(raw_ostream &o) const { 547 o << "=============================--------------------------------\n"; 548 if (this->isPostDominator()) 549 o << "Inorder PostDominator Tree: "; 550 else 551 o << "Inorder Dominator Tree: "; 552 if (!this->DFSInfoValid) 553 o << "DFSNumbers invalid: " << SlowQueries << " slow queries."; 554 o << "\n"; 555 556 // The postdom tree can have a null root if there are no returns. 557 if (getRootNode()) 558 PrintDomTree<NodeT>(getRootNode(), o, 1); 559 } 560 561protected: 562 template<class GraphT> 563 friend typename GraphT::NodeType* Eval( 564 DominatorTreeBase<typename GraphT::NodeType>& DT, 565 typename GraphT::NodeType* V, 566 unsigned LastLinked); 567 568 template<class GraphT> 569 friend unsigned DFSPass(DominatorTreeBase<typename GraphT::NodeType>& DT, 570 typename GraphT::NodeType* V, 571 unsigned N); 572 573 template<class FuncT, class N> 574 friend void Calculate(DominatorTreeBase<typename GraphTraits<N>::NodeType>& DT, 575 FuncT& F); 576 577 /// updateDFSNumbers - Assign In and Out numbers to the nodes while walking 578 /// dominator tree in dfs order. 579 void updateDFSNumbers() { 580 unsigned DFSNum = 0; 581 582 SmallVector<std::pair<DomTreeNodeBase<NodeT>*, 583 typename DomTreeNodeBase<NodeT>::iterator>, 32> WorkStack; 584 585 DomTreeNodeBase<NodeT> *ThisRoot = getRootNode(); 586 587 if (!ThisRoot) 588 return; 589 590 // Even in the case of multiple exits that form the post dominator root 591 // nodes, do not iterate over all exits, but start from the virtual root 592 // node. Otherwise bbs, that are not post dominated by any exit but by the 593 // virtual root node, will never be assigned a DFS number. 594 WorkStack.push_back(std::make_pair(ThisRoot, ThisRoot->begin())); 595 ThisRoot->DFSNumIn = DFSNum++; 596 597 while (!WorkStack.empty()) { 598 DomTreeNodeBase<NodeT> *Node = WorkStack.back().first; 599 typename DomTreeNodeBase<NodeT>::iterator ChildIt = 600 WorkStack.back().second; 601 602 // If we visited all of the children of this node, "recurse" back up the 603 // stack setting the DFOutNum. 604 if (ChildIt == Node->end()) { 605 Node->DFSNumOut = DFSNum++; 606 WorkStack.pop_back(); 607 } else { 608 // Otherwise, recursively visit this child. 609 DomTreeNodeBase<NodeT> *Child = *ChildIt; 610 ++WorkStack.back().second; 611 612 WorkStack.push_back(std::make_pair(Child, Child->begin())); 613 Child->DFSNumIn = DFSNum++; 614 } 615 } 616 617 SlowQueries = 0; 618 DFSInfoValid = true; 619 } 620 621 DomTreeNodeBase<NodeT> *getNodeForBlock(NodeT *BB) { 622 if (DomTreeNodeBase<NodeT> *Node = getNode(BB)) 623 return Node; 624 625 // Haven't calculated this node yet? Get or calculate the node for the 626 // immediate dominator. 627 NodeT *IDom = getIDom(BB); 628 629 assert(IDom || this->DomTreeNodes[NULL]); 630 DomTreeNodeBase<NodeT> *IDomNode = getNodeForBlock(IDom); 631 632 // Add a new tree node for this BasicBlock, and link it as a child of 633 // IDomNode 634 DomTreeNodeBase<NodeT> *C = new DomTreeNodeBase<NodeT>(BB, IDomNode); 635 return this->DomTreeNodes[BB] = IDomNode->addChild(C); 636 } 637 638 inline NodeT *getIDom(NodeT *BB) const { 639 return IDoms.lookup(BB); 640 } 641 642 inline void addRoot(NodeT* BB) { 643 this->Roots.push_back(BB); 644 } 645 646public: 647 /// recalculate - compute a dominator tree for the given function 648 template<class FT> 649 void recalculate(FT& F) { 650 typedef GraphTraits<FT*> TraitsTy; 651 reset(); 652 this->Vertex.push_back(0); 653 654 if (!this->IsPostDominators) { 655 // Initialize root 656 NodeT *entry = TraitsTy::getEntryNode(&F); 657 this->Roots.push_back(entry); 658 this->IDoms[entry] = 0; 659 this->DomTreeNodes[entry] = 0; 660 661 Calculate<FT, NodeT*>(*this, F); 662 } else { 663 // Initialize the roots list 664 for (typename TraitsTy::nodes_iterator I = TraitsTy::nodes_begin(&F), 665 E = TraitsTy::nodes_end(&F); I != E; ++I) { 666 if (std::distance(TraitsTy::child_begin(I), 667 TraitsTy::child_end(I)) == 0) 668 addRoot(I); 669 670 // Prepopulate maps so that we don't get iterator invalidation issues later. 671 this->IDoms[I] = 0; 672 this->DomTreeNodes[I] = 0; 673 } 674 675 Calculate<FT, Inverse<NodeT*> >(*this, F); 676 } 677 } 678}; 679 680// These two functions are declared out of line as a workaround for building 681// with old (< r147295) versions of clang because of pr11642. 682template<class NodeT> 683bool DominatorTreeBase<NodeT>::dominates(const NodeT *A, const NodeT *B) { 684 if (A == B) 685 return true; 686 687 // Cast away the const qualifiers here. This is ok since 688 // this function doesn't actually return the values returned 689 // from getNode. 690 return dominates(getNode(const_cast<NodeT *>(A)), 691 getNode(const_cast<NodeT *>(B))); 692} 693template<class NodeT> 694bool 695DominatorTreeBase<NodeT>::properlyDominates(const NodeT *A, const NodeT *B) { 696 if (A == B) 697 return false; 698 699 // Cast away the const qualifiers here. This is ok since 700 // this function doesn't actually return the values returned 701 // from getNode. 702 return dominates(getNode(const_cast<NodeT *>(A)), 703 getNode(const_cast<NodeT *>(B))); 704} 705 706EXTERN_TEMPLATE_INSTANTIATION(class DominatorTreeBase<BasicBlock>); 707 708class BasicBlockEdge; 709 710//===------------------------------------- 711/// DominatorTree Class - Concrete subclass of DominatorTreeBase that is used to 712/// compute a normal dominator tree. 713/// 714class DominatorTree : public FunctionPass { 715public: 716 static char ID; // Pass ID, replacement for typeid 717 DominatorTreeBase<BasicBlock>* DT; 718 719 DominatorTree() : FunctionPass(ID) { 720 initializeDominatorTreePass(*PassRegistry::getPassRegistry()); 721 DT = new DominatorTreeBase<BasicBlock>(false); 722 } 723 724 ~DominatorTree() { 725 delete DT; 726 } 727 728 DominatorTreeBase<BasicBlock>& getBase() { return *DT; } 729 730 /// getRoots - Return the root blocks of the current CFG. This may include 731 /// multiple blocks if we are computing post dominators. For forward 732 /// dominators, this will always be a single block (the entry node). 733 /// 734 inline const std::vector<BasicBlock*> &getRoots() const { 735 return DT->getRoots(); 736 } 737 738 inline BasicBlock *getRoot() const { 739 return DT->getRoot(); 740 } 741 742 inline DomTreeNode *getRootNode() const { 743 return DT->getRootNode(); 744 } 745 746 /// compare - Return false if the other dominator tree matches this 747 /// dominator tree. Otherwise return true. 748 inline bool compare(DominatorTree &Other) const { 749 DomTreeNode *R = getRootNode(); 750 DomTreeNode *OtherR = Other.getRootNode(); 751 752 if (!R || !OtherR || R->getBlock() != OtherR->getBlock()) 753 return true; 754 755 if (DT->compare(Other.getBase())) 756 return true; 757 758 return false; 759 } 760 761 virtual bool runOnFunction(Function &F); 762 763 virtual void verifyAnalysis() const; 764 765 virtual void getAnalysisUsage(AnalysisUsage &AU) const { 766 AU.setPreservesAll(); 767 } 768 769 inline bool dominates(const DomTreeNode* A, const DomTreeNode* B) const { 770 return DT->dominates(A, B); 771 } 772 773 inline bool dominates(const BasicBlock* A, const BasicBlock* B) const { 774 return DT->dominates(A, B); 775 } 776 777 // dominates - Return true if Def dominates a use in User. This performs 778 // the special checks necessary if Def and User are in the same basic block. 779 // Note that Def doesn't dominate a use in Def itself! 780 bool dominates(const Instruction *Def, const Use &U) const; 781 bool dominates(const Instruction *Def, const Instruction *User) const; 782 bool dominates(const Instruction *Def, const BasicBlock *BB) const; 783 bool dominates(const BasicBlockEdge &BBE, const Use &U) const; 784 bool dominates(const BasicBlockEdge &BBE, const BasicBlock *BB) const; 785 786 bool properlyDominates(const DomTreeNode *A, const DomTreeNode *B) const { 787 return DT->properlyDominates(A, B); 788 } 789 790 bool properlyDominates(const BasicBlock *A, const BasicBlock *B) const { 791 return DT->properlyDominates(A, B); 792 } 793 794 /// findNearestCommonDominator - Find nearest common dominator basic block 795 /// for basic block A and B. If there is no such block then return NULL. 796 inline BasicBlock *findNearestCommonDominator(BasicBlock *A, BasicBlock *B) { 797 return DT->findNearestCommonDominator(A, B); 798 } 799 800 inline const BasicBlock *findNearestCommonDominator(const BasicBlock *A, 801 const BasicBlock *B) { 802 return DT->findNearestCommonDominator(A, B); 803 } 804 805 inline DomTreeNode *operator[](BasicBlock *BB) const { 806 return DT->getNode(BB); 807 } 808 809 /// getNode - return the (Post)DominatorTree node for the specified basic 810 /// block. This is the same as using operator[] on this class. 811 /// 812 inline DomTreeNode *getNode(BasicBlock *BB) const { 813 return DT->getNode(BB); 814 } 815 816 /// addNewBlock - Add a new node to the dominator tree information. This 817 /// creates a new node as a child of DomBB dominator node,linking it into 818 /// the children list of the immediate dominator. 819 inline DomTreeNode *addNewBlock(BasicBlock *BB, BasicBlock *DomBB) { 820 return DT->addNewBlock(BB, DomBB); 821 } 822 823 /// changeImmediateDominator - This method is used to update the dominator 824 /// tree information when a node's immediate dominator changes. 825 /// 826 inline void changeImmediateDominator(BasicBlock *N, BasicBlock* NewIDom) { 827 DT->changeImmediateDominator(N, NewIDom); 828 } 829 830 inline void changeImmediateDominator(DomTreeNode *N, DomTreeNode* NewIDom) { 831 DT->changeImmediateDominator(N, NewIDom); 832 } 833 834 /// eraseNode - Removes a node from the dominator tree. Block must not 835 /// dominate any other blocks. Removes node from its immediate dominator's 836 /// children list. Deletes dominator node associated with basic block BB. 837 inline void eraseNode(BasicBlock *BB) { 838 DT->eraseNode(BB); 839 } 840 841 /// splitBlock - BB is split and now it has one successor. Update dominator 842 /// tree to reflect this change. 843 inline void splitBlock(BasicBlock* NewBB) { 844 DT->splitBlock(NewBB); 845 } 846 847 bool isReachableFromEntry(const BasicBlock* A) const { 848 return DT->isReachableFromEntry(A); 849 } 850 851 bool isReachableFromEntry(const Use &U) const; 852 853 854 virtual void releaseMemory() { 855 DT->releaseMemory(); 856 } 857 858 virtual void print(raw_ostream &OS, const Module* M= 0) const; 859}; 860 861//===------------------------------------- 862/// DominatorTree GraphTraits specialization so the DominatorTree can be 863/// iterable by generic graph iterators. 864/// 865template <> struct GraphTraits<DomTreeNode*> { 866 typedef DomTreeNode NodeType; 867 typedef NodeType::iterator ChildIteratorType; 868 869 static NodeType *getEntryNode(NodeType *N) { 870 return N; 871 } 872 static inline ChildIteratorType child_begin(NodeType *N) { 873 return N->begin(); 874 } 875 static inline ChildIteratorType child_end(NodeType *N) { 876 return N->end(); 877 } 878 879 typedef df_iterator<DomTreeNode*> nodes_iterator; 880 881 static nodes_iterator nodes_begin(DomTreeNode *N) { 882 return df_begin(getEntryNode(N)); 883 } 884 885 static nodes_iterator nodes_end(DomTreeNode *N) { 886 return df_end(getEntryNode(N)); 887 } 888}; 889 890template <> struct GraphTraits<DominatorTree*> 891 : public GraphTraits<DomTreeNode*> { 892 static NodeType *getEntryNode(DominatorTree *DT) { 893 return DT->getRootNode(); 894 } 895 896 static nodes_iterator nodes_begin(DominatorTree *N) { 897 return df_begin(getEntryNode(N)); 898 } 899 900 static nodes_iterator nodes_end(DominatorTree *N) { 901 return df_end(getEntryNode(N)); 902 } 903}; 904 905 906} // End llvm namespace 907 908#endif 909