Dominators.h revision 263508
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/ADT/DenseMap.h" 19#include "llvm/ADT/DepthFirstIterator.h" 20#include "llvm/ADT/GraphTraits.h" 21#include "llvm/ADT/SmallPtrSet.h" 22#include "llvm/ADT/SmallVector.h" 23#include "llvm/IR/Function.h" 24#include "llvm/Pass.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(const DomTreeNodeBase<NodeT> *Other) const { 105 if (getNumChildren() != Other->getNumChildren()) 106 return true; 107 108 SmallPtrSet<const NodeT *, 4> OtherChildren; 109 for (const_iterator I = Other->begin(), E = Other->end(); I != E; ++I) { 110 const NodeT *Nd = (*I)->getBlock(); 111 OtherChildren.insert(Nd); 112 } 113 114 for (const_iterator I = begin(), E = end(); I != E; ++I) { 115 const 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 /// Get all nodes dominated by R, including R itself. Return true on success. 350 void getDescendants(NodeT *R, SmallVectorImpl<NodeT *> &Result) const { 351 const DomTreeNodeBase<NodeT> *RN = getNode(R); 352 SmallVector<const DomTreeNodeBase<NodeT> *, 8> WL; 353 WL.push_back(RN); 354 Result.clear(); 355 356 while (!WL.empty()) { 357 const DomTreeNodeBase<NodeT> *N = WL.pop_back_val(); 358 Result.push_back(N->getBlock()); 359 WL.append(N->begin(), N->end()); 360 } 361 } 362 363 /// properlyDominates - Returns true iff A dominates B and A != B. 364 /// Note that this is not a constant time operation! 365 /// 366 bool properlyDominates(const DomTreeNodeBase<NodeT> *A, 367 const DomTreeNodeBase<NodeT> *B) { 368 if (A == 0 || B == 0) 369 return false; 370 if (A == B) 371 return false; 372 return dominates(A, B); 373 } 374 375 bool properlyDominates(const NodeT *A, const NodeT *B); 376 377 /// isReachableFromEntry - Return true if A is dominated by the entry 378 /// block of the function containing it. 379 bool isReachableFromEntry(const NodeT* A) const { 380 assert(!this->isPostDominator() && 381 "This is not implemented for post dominators"); 382 return isReachableFromEntry(getNode(const_cast<NodeT *>(A))); 383 } 384 385 inline bool isReachableFromEntry(const DomTreeNodeBase<NodeT> *A) const { 386 return A; 387 } 388 389 /// dominates - Returns true iff A dominates B. Note that this is not a 390 /// constant time operation! 391 /// 392 inline bool dominates(const DomTreeNodeBase<NodeT> *A, 393 const DomTreeNodeBase<NodeT> *B) { 394 // A node trivially dominates itself. 395 if (B == A) 396 return true; 397 398 // An unreachable node is dominated by anything. 399 if (!isReachableFromEntry(B)) 400 return true; 401 402 // And dominates nothing. 403 if (!isReachableFromEntry(A)) 404 return false; 405 406 // Compare the result of the tree walk and the dfs numbers, if expensive 407 // checks are enabled. 408#ifdef XDEBUG 409 assert((!DFSInfoValid || 410 (dominatedBySlowTreeWalk(A, B) == B->DominatedBy(A))) && 411 "Tree walk disagrees with dfs numbers!"); 412#endif 413 414 if (DFSInfoValid) 415 return B->DominatedBy(A); 416 417 // If we end up with too many slow queries, just update the 418 // DFS numbers on the theory that we are going to keep querying. 419 SlowQueries++; 420 if (SlowQueries > 32) { 421 updateDFSNumbers(); 422 return B->DominatedBy(A); 423 } 424 425 return dominatedBySlowTreeWalk(A, B); 426 } 427 428 bool dominates(const NodeT *A, const NodeT *B); 429 430 NodeT *getRoot() const { 431 assert(this->Roots.size() == 1 && "Should always have entry node!"); 432 return this->Roots[0]; 433 } 434 435 /// findNearestCommonDominator - Find nearest common dominator basic block 436 /// for basic block A and B. If there is no such block then return NULL. 437 NodeT *findNearestCommonDominator(NodeT *A, NodeT *B) { 438 assert(A->getParent() == B->getParent() && 439 "Two blocks are not in same function"); 440 441 // If either A or B is a entry block then it is nearest common dominator 442 // (for forward-dominators). 443 if (!this->isPostDominator()) { 444 NodeT &Entry = A->getParent()->front(); 445 if (A == &Entry || B == &Entry) 446 return &Entry; 447 } 448 449 // If B dominates A then B is nearest common dominator. 450 if (dominates(B, A)) 451 return B; 452 453 // If A dominates B then A is nearest common dominator. 454 if (dominates(A, B)) 455 return A; 456 457 DomTreeNodeBase<NodeT> *NodeA = getNode(A); 458 DomTreeNodeBase<NodeT> *NodeB = getNode(B); 459 460 // Collect NodeA dominators set. 461 SmallPtrSet<DomTreeNodeBase<NodeT>*, 16> NodeADoms; 462 NodeADoms.insert(NodeA); 463 DomTreeNodeBase<NodeT> *IDomA = NodeA->getIDom(); 464 while (IDomA) { 465 NodeADoms.insert(IDomA); 466 IDomA = IDomA->getIDom(); 467 } 468 469 // Walk NodeB immediate dominators chain and find common dominator node. 470 DomTreeNodeBase<NodeT> *IDomB = NodeB->getIDom(); 471 while (IDomB) { 472 if (NodeADoms.count(IDomB) != 0) 473 return IDomB->getBlock(); 474 475 IDomB = IDomB->getIDom(); 476 } 477 478 return NULL; 479 } 480 481 const NodeT *findNearestCommonDominator(const NodeT *A, const NodeT *B) { 482 // Cast away the const qualifiers here. This is ok since 483 // const is re-introduced on the return type. 484 return findNearestCommonDominator(const_cast<NodeT *>(A), 485 const_cast<NodeT *>(B)); 486 } 487 488 //===--------------------------------------------------------------------===// 489 // API to update (Post)DominatorTree information based on modifications to 490 // the CFG... 491 492 /// addNewBlock - Add a new node to the dominator tree information. This 493 /// creates a new node as a child of DomBB dominator node,linking it into 494 /// the children list of the immediate dominator. 495 DomTreeNodeBase<NodeT> *addNewBlock(NodeT *BB, NodeT *DomBB) { 496 assert(getNode(BB) == 0 && "Block already in dominator tree!"); 497 DomTreeNodeBase<NodeT> *IDomNode = getNode(DomBB); 498 assert(IDomNode && "Not immediate dominator specified for block!"); 499 DFSInfoValid = false; 500 return DomTreeNodes[BB] = 501 IDomNode->addChild(new DomTreeNodeBase<NodeT>(BB, IDomNode)); 502 } 503 504 /// changeImmediateDominator - This method is used to update the dominator 505 /// tree information when a node's immediate dominator changes. 506 /// 507 void changeImmediateDominator(DomTreeNodeBase<NodeT> *N, 508 DomTreeNodeBase<NodeT> *NewIDom) { 509 assert(N && NewIDom && "Cannot change null node pointers!"); 510 DFSInfoValid = false; 511 N->setIDom(NewIDom); 512 } 513 514 void changeImmediateDominator(NodeT *BB, NodeT *NewBB) { 515 changeImmediateDominator(getNode(BB), getNode(NewBB)); 516 } 517 518 /// eraseNode - Removes a node from the dominator tree. Block must not 519 /// dominate any other blocks. Removes node from its immediate dominator's 520 /// children list. Deletes dominator node associated with basic block BB. 521 void eraseNode(NodeT *BB) { 522 DomTreeNodeBase<NodeT> *Node = getNode(BB); 523 assert(Node && "Removing node that isn't in dominator tree."); 524 assert(Node->getChildren().empty() && "Node is not a leaf node."); 525 526 // Remove node from immediate dominator's children list. 527 DomTreeNodeBase<NodeT> *IDom = Node->getIDom(); 528 if (IDom) { 529 typename std::vector<DomTreeNodeBase<NodeT>*>::iterator I = 530 std::find(IDom->Children.begin(), IDom->Children.end(), Node); 531 assert(I != IDom->Children.end() && 532 "Not in immediate dominator children set!"); 533 // I am no longer your child... 534 IDom->Children.erase(I); 535 } 536 537 DomTreeNodes.erase(BB); 538 delete Node; 539 } 540 541 /// removeNode - Removes a node from the dominator tree. Block must not 542 /// dominate any other blocks. Invalidates any node pointing to removed 543 /// block. 544 void removeNode(NodeT *BB) { 545 assert(getNode(BB) && "Removing node that isn't in dominator tree."); 546 DomTreeNodes.erase(BB); 547 } 548 549 /// splitBlock - BB is split and now it has one successor. Update dominator 550 /// tree to reflect this change. 551 void splitBlock(NodeT* NewBB) { 552 if (this->IsPostDominators) 553 this->Split<Inverse<NodeT*>, GraphTraits<Inverse<NodeT*> > >(*this, NewBB); 554 else 555 this->Split<NodeT*, GraphTraits<NodeT*> >(*this, NewBB); 556 } 557 558 /// print - Convert to human readable form 559 /// 560 void print(raw_ostream &o) const { 561 o << "=============================--------------------------------\n"; 562 if (this->isPostDominator()) 563 o << "Inorder PostDominator Tree: "; 564 else 565 o << "Inorder Dominator Tree: "; 566 if (!this->DFSInfoValid) 567 o << "DFSNumbers invalid: " << SlowQueries << " slow queries."; 568 o << "\n"; 569 570 // The postdom tree can have a null root if there are no returns. 571 if (getRootNode()) 572 PrintDomTree<NodeT>(getRootNode(), o, 1); 573 } 574 575protected: 576 template<class GraphT> 577 friend typename GraphT::NodeType* Eval( 578 DominatorTreeBase<typename GraphT::NodeType>& DT, 579 typename GraphT::NodeType* V, 580 unsigned LastLinked); 581 582 template<class GraphT> 583 friend unsigned DFSPass(DominatorTreeBase<typename GraphT::NodeType>& DT, 584 typename GraphT::NodeType* V, 585 unsigned N); 586 587 template<class FuncT, class N> 588 friend void Calculate(DominatorTreeBase<typename GraphTraits<N>::NodeType>& DT, 589 FuncT& F); 590 591 /// updateDFSNumbers - Assign In and Out numbers to the nodes while walking 592 /// dominator tree in dfs order. 593 void updateDFSNumbers() { 594 unsigned DFSNum = 0; 595 596 SmallVector<std::pair<DomTreeNodeBase<NodeT>*, 597 typename DomTreeNodeBase<NodeT>::iterator>, 32> WorkStack; 598 599 DomTreeNodeBase<NodeT> *ThisRoot = getRootNode(); 600 601 if (!ThisRoot) 602 return; 603 604 // Even in the case of multiple exits that form the post dominator root 605 // nodes, do not iterate over all exits, but start from the virtual root 606 // node. Otherwise bbs, that are not post dominated by any exit but by the 607 // virtual root node, will never be assigned a DFS number. 608 WorkStack.push_back(std::make_pair(ThisRoot, ThisRoot->begin())); 609 ThisRoot->DFSNumIn = DFSNum++; 610 611 while (!WorkStack.empty()) { 612 DomTreeNodeBase<NodeT> *Node = WorkStack.back().first; 613 typename DomTreeNodeBase<NodeT>::iterator ChildIt = 614 WorkStack.back().second; 615 616 // If we visited all of the children of this node, "recurse" back up the 617 // stack setting the DFOutNum. 618 if (ChildIt == Node->end()) { 619 Node->DFSNumOut = DFSNum++; 620 WorkStack.pop_back(); 621 } else { 622 // Otherwise, recursively visit this child. 623 DomTreeNodeBase<NodeT> *Child = *ChildIt; 624 ++WorkStack.back().second; 625 626 WorkStack.push_back(std::make_pair(Child, Child->begin())); 627 Child->DFSNumIn = DFSNum++; 628 } 629 } 630 631 SlowQueries = 0; 632 DFSInfoValid = true; 633 } 634 635 DomTreeNodeBase<NodeT> *getNodeForBlock(NodeT *BB) { 636 if (DomTreeNodeBase<NodeT> *Node = getNode(BB)) 637 return Node; 638 639 // Haven't calculated this node yet? Get or calculate the node for the 640 // immediate dominator. 641 NodeT *IDom = getIDom(BB); 642 643 assert(IDom || this->DomTreeNodes[NULL]); 644 DomTreeNodeBase<NodeT> *IDomNode = getNodeForBlock(IDom); 645 646 // Add a new tree node for this BasicBlock, and link it as a child of 647 // IDomNode 648 DomTreeNodeBase<NodeT> *C = new DomTreeNodeBase<NodeT>(BB, IDomNode); 649 return this->DomTreeNodes[BB] = IDomNode->addChild(C); 650 } 651 652 inline NodeT *getIDom(NodeT *BB) const { 653 return IDoms.lookup(BB); 654 } 655 656 inline void addRoot(NodeT* BB) { 657 this->Roots.push_back(BB); 658 } 659 660public: 661 /// recalculate - compute a dominator tree for the given function 662 template<class FT> 663 void recalculate(FT& F) { 664 typedef GraphTraits<FT*> TraitsTy; 665 reset(); 666 this->Vertex.push_back(0); 667 668 if (!this->IsPostDominators) { 669 // Initialize root 670 NodeT *entry = TraitsTy::getEntryNode(&F); 671 this->Roots.push_back(entry); 672 this->IDoms[entry] = 0; 673 this->DomTreeNodes[entry] = 0; 674 675 Calculate<FT, NodeT*>(*this, F); 676 } else { 677 // Initialize the roots list 678 for (typename TraitsTy::nodes_iterator I = TraitsTy::nodes_begin(&F), 679 E = TraitsTy::nodes_end(&F); I != E; ++I) { 680 if (TraitsTy::child_begin(I) == TraitsTy::child_end(I)) 681 addRoot(I); 682 683 // Prepopulate maps so that we don't get iterator invalidation issues later. 684 this->IDoms[I] = 0; 685 this->DomTreeNodes[I] = 0; 686 } 687 688 Calculate<FT, Inverse<NodeT*> >(*this, F); 689 } 690 } 691}; 692 693// These two functions are declared out of line as a workaround for building 694// with old (< r147295) versions of clang because of pr11642. 695template<class NodeT> 696bool DominatorTreeBase<NodeT>::dominates(const NodeT *A, const NodeT *B) { 697 if (A == B) 698 return true; 699 700 // Cast away the const qualifiers here. This is ok since 701 // this function doesn't actually return the values returned 702 // from getNode. 703 return dominates(getNode(const_cast<NodeT *>(A)), 704 getNode(const_cast<NodeT *>(B))); 705} 706template<class NodeT> 707bool 708DominatorTreeBase<NodeT>::properlyDominates(const NodeT *A, const NodeT *B) { 709 if (A == B) 710 return false; 711 712 // Cast away the const qualifiers here. This is ok since 713 // this function doesn't actually return the values returned 714 // from getNode. 715 return dominates(getNode(const_cast<NodeT *>(A)), 716 getNode(const_cast<NodeT *>(B))); 717} 718 719EXTERN_TEMPLATE_INSTANTIATION(class DominatorTreeBase<BasicBlock>); 720 721class BasicBlockEdge { 722 const BasicBlock *Start; 723 const BasicBlock *End; 724public: 725 BasicBlockEdge(const BasicBlock *Start_, const BasicBlock *End_) : 726 Start(Start_), End(End_) { } 727 const BasicBlock *getStart() const { 728 return Start; 729 } 730 const BasicBlock *getEnd() const { 731 return End; 732 } 733 bool isSingleEdge() const; 734}; 735 736//===------------------------------------- 737/// DominatorTree Class - Concrete subclass of DominatorTreeBase that is used to 738/// compute a normal dominator tree. 739/// 740class DominatorTree : public FunctionPass { 741public: 742 static char ID; // Pass ID, replacement for typeid 743 DominatorTreeBase<BasicBlock>* DT; 744 745 DominatorTree() : FunctionPass(ID) { 746 initializeDominatorTreePass(*PassRegistry::getPassRegistry()); 747 DT = new DominatorTreeBase<BasicBlock>(false); 748 } 749 750 ~DominatorTree() { 751 delete DT; 752 } 753 754 DominatorTreeBase<BasicBlock>& getBase() { return *DT; } 755 756 /// getRoots - Return the root blocks of the current CFG. This may include 757 /// multiple blocks if we are computing post dominators. For forward 758 /// dominators, this will always be a single block (the entry node). 759 /// 760 inline const std::vector<BasicBlock*> &getRoots() const { 761 return DT->getRoots(); 762 } 763 764 inline BasicBlock *getRoot() const { 765 return DT->getRoot(); 766 } 767 768 inline DomTreeNode *getRootNode() const { 769 return DT->getRootNode(); 770 } 771 772 /// Get all nodes dominated by R, including R itself. Return true on success. 773 void getDescendants(BasicBlock *R, 774 SmallVectorImpl<BasicBlock *> &Result) const { 775 DT->getDescendants(R, Result); 776 } 777 778 /// compare - Return false if the other dominator tree matches this 779 /// dominator tree. Otherwise return true. 780 inline bool compare(DominatorTree &Other) const { 781 DomTreeNode *R = getRootNode(); 782 DomTreeNode *OtherR = Other.getRootNode(); 783 784 if (!R || !OtherR || R->getBlock() != OtherR->getBlock()) 785 return true; 786 787 if (DT->compare(Other.getBase())) 788 return true; 789 790 return false; 791 } 792 793 virtual bool runOnFunction(Function &F); 794 795 virtual void verifyAnalysis() const; 796 797 virtual void getAnalysisUsage(AnalysisUsage &AU) const { 798 AU.setPreservesAll(); 799 } 800 801 inline bool dominates(const DomTreeNode* A, const DomTreeNode* B) const { 802 return DT->dominates(A, B); 803 } 804 805 inline bool dominates(const BasicBlock* A, const BasicBlock* B) const { 806 return DT->dominates(A, B); 807 } 808 809 // dominates - Return true if Def dominates a use in User. This performs 810 // the special checks necessary if Def and User are in the same basic block. 811 // Note that Def doesn't dominate a use in Def itself! 812 bool dominates(const Instruction *Def, const Use &U) const; 813 bool dominates(const Instruction *Def, const Instruction *User) const; 814 bool dominates(const Instruction *Def, const BasicBlock *BB) const; 815 bool dominates(const BasicBlockEdge &BBE, const Use &U) const; 816 bool dominates(const BasicBlockEdge &BBE, const BasicBlock *BB) const; 817 818 bool properlyDominates(const DomTreeNode *A, const DomTreeNode *B) const { 819 return DT->properlyDominates(A, B); 820 } 821 822 bool properlyDominates(const BasicBlock *A, const BasicBlock *B) const { 823 return DT->properlyDominates(A, B); 824 } 825 826 /// findNearestCommonDominator - Find nearest common dominator basic block 827 /// for basic block A and B. If there is no such block then return NULL. 828 inline BasicBlock *findNearestCommonDominator(BasicBlock *A, BasicBlock *B) { 829 return DT->findNearestCommonDominator(A, B); 830 } 831 832 inline const BasicBlock *findNearestCommonDominator(const BasicBlock *A, 833 const BasicBlock *B) { 834 return DT->findNearestCommonDominator(A, B); 835 } 836 837 inline DomTreeNode *operator[](BasicBlock *BB) const { 838 return DT->getNode(BB); 839 } 840 841 /// getNode - return the (Post)DominatorTree node for the specified basic 842 /// block. This is the same as using operator[] on this class. 843 /// 844 inline DomTreeNode *getNode(BasicBlock *BB) const { 845 return DT->getNode(BB); 846 } 847 848 /// addNewBlock - Add a new node to the dominator tree information. This 849 /// creates a new node as a child of DomBB dominator node,linking it into 850 /// the children list of the immediate dominator. 851 inline DomTreeNode *addNewBlock(BasicBlock *BB, BasicBlock *DomBB) { 852 return DT->addNewBlock(BB, DomBB); 853 } 854 855 /// changeImmediateDominator - This method is used to update the dominator 856 /// tree information when a node's immediate dominator changes. 857 /// 858 inline void changeImmediateDominator(BasicBlock *N, BasicBlock* NewIDom) { 859 DT->changeImmediateDominator(N, NewIDom); 860 } 861 862 inline void changeImmediateDominator(DomTreeNode *N, DomTreeNode* NewIDom) { 863 DT->changeImmediateDominator(N, NewIDom); 864 } 865 866 /// eraseNode - Removes a node from the dominator tree. Block must not 867 /// dominate any other blocks. Removes node from its immediate dominator's 868 /// children list. Deletes dominator node associated with basic block BB. 869 inline void eraseNode(BasicBlock *BB) { 870 DT->eraseNode(BB); 871 } 872 873 /// splitBlock - BB is split and now it has one successor. Update dominator 874 /// tree to reflect this change. 875 inline void splitBlock(BasicBlock* NewBB) { 876 DT->splitBlock(NewBB); 877 } 878 879 bool isReachableFromEntry(const BasicBlock* A) const { 880 return DT->isReachableFromEntry(A); 881 } 882 883 bool isReachableFromEntry(const Use &U) const; 884 885 886 virtual void releaseMemory() { 887 DT->releaseMemory(); 888 } 889 890 virtual void print(raw_ostream &OS, const Module* M= 0) const; 891}; 892 893//===------------------------------------- 894/// DominatorTree GraphTraits specialization so the DominatorTree can be 895/// iterable by generic graph iterators. 896/// 897template <> struct GraphTraits<DomTreeNode*> { 898 typedef DomTreeNode NodeType; 899 typedef NodeType::iterator ChildIteratorType; 900 901 static NodeType *getEntryNode(NodeType *N) { 902 return N; 903 } 904 static inline ChildIteratorType child_begin(NodeType *N) { 905 return N->begin(); 906 } 907 static inline ChildIteratorType child_end(NodeType *N) { 908 return N->end(); 909 } 910 911 typedef df_iterator<DomTreeNode*> nodes_iterator; 912 913 static nodes_iterator nodes_begin(DomTreeNode *N) { 914 return df_begin(getEntryNode(N)); 915 } 916 917 static nodes_iterator nodes_end(DomTreeNode *N) { 918 return df_end(getEntryNode(N)); 919 } 920}; 921 922template <> struct GraphTraits<DominatorTree*> 923 : public GraphTraits<DomTreeNode*> { 924 static NodeType *getEntryNode(DominatorTree *DT) { 925 return DT->getRootNode(); 926 } 927 928 static nodes_iterator nodes_begin(DominatorTree *N) { 929 return df_begin(getEntryNode(N)); 930 } 931 932 static nodes_iterator nodes_end(DominatorTree *N) { 933 return df_end(getEntryNode(N)); 934 } 935}; 936 937 938} // End llvm namespace 939 940#endif 941