Dominators.h revision 3a723ab344d9835506ed2b52a2ccd75078670fc7
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> 155static 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> 168static 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> { 188protected: 189 typedef DenseMap<NodeT*, DomTreeNodeBase<NodeT>*> DomTreeNodeMapType; 190 DomTreeNodeMapType DomTreeNodes; 191 DomTreeNodeBase<NodeT> *RootNode; 192 193 bool DFSInfoValid; 194 unsigned int SlowQueries; 195 // Information record used during immediate dominators computation. 196 struct InfoRec { 197 unsigned DFSNum; 198 unsigned Semi; 199 unsigned Size; 200 NodeT *Label, *Child; 201 unsigned Parent, Ancestor; 202 203 InfoRec() : DFSNum(0), Semi(0), Size(0), Label(0), Child(0), Parent(0), 204 Ancestor(0) {} 205 }; 206 207 DenseMap<NodeT*, NodeT*> IDoms; 208 209 // Vertex - Map the DFS number to the BasicBlock* 210 std::vector<NodeT*> Vertex; 211 212 // Info - Collection of information used during the computation of idoms. 213 DenseMap<NodeT*, InfoRec> Info; 214 215 void reset() { 216 for (typename DomTreeNodeMapType::iterator I = this->DomTreeNodes.begin(), 217 E = DomTreeNodes.end(); I != E; ++I) 218 delete I->second; 219 DomTreeNodes.clear(); 220 IDoms.clear(); 221 this->Roots.clear(); 222 Vertex.clear(); 223 RootNode = 0; 224 } 225 226 // NewBB is split and now it has one successor. Update dominator tree to 227 // reflect this change. 228 template<class N, class GraphT> 229 void Split(DominatorTreeBase<typename GraphT::NodeType>& DT, 230 typename GraphT::NodeType* NewBB) { 231 assert(std::distance(GraphT::child_begin(NewBB), 232 GraphT::child_end(NewBB)) == 1 && 233 "NewBB should have a single successor!"); 234 typename GraphT::NodeType* NewBBSucc = *GraphT::child_begin(NewBB); 235 236 std::vector<typename GraphT::NodeType*> PredBlocks; 237 typedef GraphTraits<Inverse<N> > InvTraits; 238 for (typename InvTraits::ChildIteratorType PI = 239 InvTraits::child_begin(NewBB), 240 PE = InvTraits::child_end(NewBB); PI != PE; ++PI) 241 PredBlocks.push_back(*PI); 242 243 assert(!PredBlocks.empty() && "No predblocks?"); 244 245 bool NewBBDominatesNewBBSucc = true; 246 for (typename InvTraits::ChildIteratorType PI = 247 InvTraits::child_begin(NewBBSucc), 248 E = InvTraits::child_end(NewBBSucc); PI != E; ++PI) { 249 typename InvTraits::NodeType *ND = *PI; 250 if (ND != NewBB && !DT.dominates(NewBBSucc, ND) && 251 DT.isReachableFromEntry(ND)) { 252 NewBBDominatesNewBBSucc = false; 253 break; 254 } 255 } 256 257 // Find NewBB's immediate dominator and create new dominator tree node for 258 // NewBB. 259 NodeT *NewBBIDom = 0; 260 unsigned i = 0; 261 for (i = 0; i < PredBlocks.size(); ++i) 262 if (DT.isReachableFromEntry(PredBlocks[i])) { 263 NewBBIDom = PredBlocks[i]; 264 break; 265 } 266 267 // It's possible that none of the predecessors of NewBB are reachable; 268 // in that case, NewBB itself is unreachable, so nothing needs to be 269 // changed. 270 if (!NewBBIDom) 271 return; 272 273 for (i = i + 1; i < PredBlocks.size(); ++i) { 274 if (DT.isReachableFromEntry(PredBlocks[i])) 275 NewBBIDom = DT.findNearestCommonDominator(NewBBIDom, PredBlocks[i]); 276 } 277 278 // Create the new dominator tree node... and set the idom of NewBB. 279 DomTreeNodeBase<NodeT> *NewBBNode = DT.addNewBlock(NewBB, NewBBIDom); 280 281 // If NewBB strictly dominates other blocks, then it is now the immediate 282 // dominator of NewBBSucc. Update the dominator tree as appropriate. 283 if (NewBBDominatesNewBBSucc) { 284 DomTreeNodeBase<NodeT> *NewBBSuccNode = DT.getNode(NewBBSucc); 285 DT.changeImmediateDominator(NewBBSuccNode, NewBBNode); 286 } 287 } 288 289public: 290 explicit DominatorTreeBase(bool isPostDom) 291 : DominatorBase<NodeT>(isPostDom), DFSInfoValid(false), SlowQueries(0) {} 292 virtual ~DominatorTreeBase() { reset(); } 293 294 /// compare - Return false if the other dominator tree base matches this 295 /// dominator tree base. Otherwise return true. 296 bool compare(DominatorTreeBase &Other) const { 297 298 const DomTreeNodeMapType &OtherDomTreeNodes = Other.DomTreeNodes; 299 if (DomTreeNodes.size() != OtherDomTreeNodes.size()) 300 return true; 301 302 for (typename DomTreeNodeMapType::const_iterator 303 I = this->DomTreeNodes.begin(), 304 E = this->DomTreeNodes.end(); I != E; ++I) { 305 NodeT *BB = I->first; 306 typename DomTreeNodeMapType::const_iterator OI = OtherDomTreeNodes.find(BB); 307 if (OI == OtherDomTreeNodes.end()) 308 return true; 309 310 DomTreeNodeBase<NodeT>* MyNd = I->second; 311 DomTreeNodeBase<NodeT>* OtherNd = OI->second; 312 313 if (MyNd->compare(OtherNd)) 314 return true; 315 } 316 317 return false; 318 } 319 320 virtual void releaseMemory() { reset(); } 321 322 /// getNode - return the (Post)DominatorTree node for the specified basic 323 /// block. This is the same as using operator[] on this class. 324 /// 325 inline DomTreeNodeBase<NodeT> *getNode(NodeT *BB) const { 326 typename DomTreeNodeMapType::const_iterator I = DomTreeNodes.find(BB); 327 return I != DomTreeNodes.end() ? I->second : 0; 328 } 329 330 /// getRootNode - This returns the entry node for the CFG of the function. If 331 /// this tree represents the post-dominance relations for a function, however, 332 /// this root may be a node with the block == NULL. This is the case when 333 /// there are multiple exit nodes from a particular function. Consumers of 334 /// post-dominance information must be capable of dealing with this 335 /// possibility. 336 /// 337 DomTreeNodeBase<NodeT> *getRootNode() { return RootNode; } 338 const DomTreeNodeBase<NodeT> *getRootNode() const { return RootNode; } 339 340 /// properlyDominates - Returns true iff this dominates N and this != N. 341 /// Note that this is not a constant time operation! 342 /// 343 bool properlyDominates(const DomTreeNodeBase<NodeT> *A, 344 const DomTreeNodeBase<NodeT> *B) const { 345 if (A == 0 || B == 0) return false; 346 return dominatedBySlowTreeWalk(A, B); 347 } 348 349 inline bool properlyDominates(const NodeT *A, const NodeT *B) { 350 if (A == B) 351 return false; 352 353 // Cast away the const qualifiers here. This is ok since 354 // this function doesn't actually return the values returned 355 // from getNode. 356 return properlyDominates(getNode(const_cast<NodeT *>(A)), 357 getNode(const_cast<NodeT *>(B))); 358 } 359 360 bool dominatedBySlowTreeWalk(const DomTreeNodeBase<NodeT> *A, 361 const DomTreeNodeBase<NodeT> *B) const { 362 const DomTreeNodeBase<NodeT> *IDom; 363 if (A == 0 || B == 0) return false; 364 while ((IDom = B->getIDom()) != 0 && IDom != A && IDom != B) 365 B = IDom; // Walk up the tree 366 return IDom != 0; 367 } 368 369 370 /// isReachableFromEntry - Return true if A is dominated by the entry 371 /// block of the function containing it. 372 bool isReachableFromEntry(const NodeT* A) { 373 assert(!this->isPostDominator() && 374 "This is not implemented for post dominators"); 375 return dominates(&A->getParent()->front(), A); 376 } 377 378 /// dominates - Returns true iff A dominates B. Note that this is not a 379 /// constant time operation! 380 /// 381 inline bool dominates(const DomTreeNodeBase<NodeT> *A, 382 const DomTreeNodeBase<NodeT> *B) { 383 if (B == A) 384 return true; // A node trivially dominates itself. 385 386 if (A == 0 || B == 0) 387 return false; 388 389 // Compare the result of the tree walk and the dfs numbers, if expensive 390 // checks are enabled. 391#ifdef XDEBUG 392 assert((!DFSInfoValid || 393 (dominatedBySlowTreeWalk(A, B) == B->DominatedBy(A))) && 394 "Tree walk disagrees with dfs numbers!"); 395#endif 396 397 if (DFSInfoValid) 398 return B->DominatedBy(A); 399 400 // If we end up with too many slow queries, just update the 401 // DFS numbers on the theory that we are going to keep querying. 402 SlowQueries++; 403 if (SlowQueries > 32) { 404 updateDFSNumbers(); 405 return B->DominatedBy(A); 406 } 407 408 return dominatedBySlowTreeWalk(A, B); 409 } 410 411 inline bool dominates(const NodeT *A, const NodeT *B) { 412 if (A == B) 413 return true; 414 415 // Cast away the const qualifiers here. This is ok since 416 // this function doesn't actually return the values returned 417 // from getNode. 418 return dominates(getNode(const_cast<NodeT *>(A)), 419 getNode(const_cast<NodeT *>(B))); 420 } 421 422 NodeT *getRoot() const { 423 assert(this->Roots.size() == 1 && "Should always have entry node!"); 424 return this->Roots[0]; 425 } 426 427 /// findNearestCommonDominator - Find nearest common dominator basic block 428 /// for basic block A and B. If there is no such block then return NULL. 429 NodeT *findNearestCommonDominator(NodeT *A, NodeT *B) { 430 assert(A->getParent() == B->getParent() && 431 "Two blocks are not in same function"); 432 433 // If either A or B is a entry block then it is nearest common dominator 434 // (for forward-dominators). 435 if (!this->isPostDominator()) { 436 NodeT &Entry = A->getParent()->front(); 437 if (A == &Entry || B == &Entry) 438 return &Entry; 439 } 440 441 // If B dominates A then B is nearest common dominator. 442 if (dominates(B, A)) 443 return B; 444 445 // If A dominates B then A is nearest common dominator. 446 if (dominates(A, B)) 447 return A; 448 449 DomTreeNodeBase<NodeT> *NodeA = getNode(A); 450 DomTreeNodeBase<NodeT> *NodeB = getNode(B); 451 452 // Collect NodeA dominators set. 453 SmallPtrSet<DomTreeNodeBase<NodeT>*, 16> NodeADoms; 454 NodeADoms.insert(NodeA); 455 DomTreeNodeBase<NodeT> *IDomA = NodeA->getIDom(); 456 while (IDomA) { 457 NodeADoms.insert(IDomA); 458 IDomA = IDomA->getIDom(); 459 } 460 461 // Walk NodeB immediate dominators chain and find common dominator node. 462 DomTreeNodeBase<NodeT> *IDomB = NodeB->getIDom(); 463 while (IDomB) { 464 if (NodeADoms.count(IDomB) != 0) 465 return IDomB->getBlock(); 466 467 IDomB = IDomB->getIDom(); 468 } 469 470 return NULL; 471 } 472 473 const NodeT *findNearestCommonDominator(const NodeT *A, const NodeT *B) { 474 // Cast away the const qualifiers here. This is ok since 475 // const is re-introduced on the return type. 476 return findNearestCommonDominator(const_cast<NodeT *>(A), 477 const_cast<NodeT *>(B)); 478 } 479 480 //===--------------------------------------------------------------------===// 481 // API to update (Post)DominatorTree information based on modifications to 482 // the CFG... 483 484 /// addNewBlock - Add a new node to the dominator tree information. This 485 /// creates a new node as a child of DomBB dominator node,linking it into 486 /// the children list of the immediate dominator. 487 DomTreeNodeBase<NodeT> *addNewBlock(NodeT *BB, NodeT *DomBB) { 488 assert(getNode(BB) == 0 && "Block already in dominator tree!"); 489 DomTreeNodeBase<NodeT> *IDomNode = getNode(DomBB); 490 assert(IDomNode && "Not immediate dominator specified for block!"); 491 DFSInfoValid = false; 492 return DomTreeNodes[BB] = 493 IDomNode->addChild(new DomTreeNodeBase<NodeT>(BB, IDomNode)); 494 } 495 496 /// changeImmediateDominator - This method is used to update the dominator 497 /// tree information when a node's immediate dominator changes. 498 /// 499 void changeImmediateDominator(DomTreeNodeBase<NodeT> *N, 500 DomTreeNodeBase<NodeT> *NewIDom) { 501 assert(N && NewIDom && "Cannot change null node pointers!"); 502 DFSInfoValid = false; 503 N->setIDom(NewIDom); 504 } 505 506 void changeImmediateDominator(NodeT *BB, NodeT *NewBB) { 507 changeImmediateDominator(getNode(BB), getNode(NewBB)); 508 } 509 510 /// eraseNode - Removes a node from the dominator tree. Block must not 511 /// dominate any other blocks. Removes node from its immediate dominator's 512 /// children list. Deletes dominator node associated with basic block BB. 513 void eraseNode(NodeT *BB) { 514 DomTreeNodeBase<NodeT> *Node = getNode(BB); 515 assert(Node && "Removing node that isn't in dominator tree."); 516 assert(Node->getChildren().empty() && "Node is not a leaf node."); 517 518 // Remove node from immediate dominator's children list. 519 DomTreeNodeBase<NodeT> *IDom = Node->getIDom(); 520 if (IDom) { 521 typename std::vector<DomTreeNodeBase<NodeT>*>::iterator I = 522 std::find(IDom->Children.begin(), IDom->Children.end(), Node); 523 assert(I != IDom->Children.end() && 524 "Not in immediate dominator children set!"); 525 // I am no longer your child... 526 IDom->Children.erase(I); 527 } 528 529 DomTreeNodes.erase(BB); 530 delete Node; 531 } 532 533 /// removeNode - Removes a node from the dominator tree. Block must not 534 /// dominate any other blocks. Invalidates any node pointing to removed 535 /// block. 536 void removeNode(NodeT *BB) { 537 assert(getNode(BB) && "Removing node that isn't in dominator tree."); 538 DomTreeNodes.erase(BB); 539 } 540 541 /// splitBlock - BB is split and now it has one successor. Update dominator 542 /// tree to reflect this change. 543 void splitBlock(NodeT* NewBB) { 544 if (this->IsPostDominators) 545 this->Split<Inverse<NodeT*>, GraphTraits<Inverse<NodeT*> > >(*this, NewBB); 546 else 547 this->Split<NodeT*, GraphTraits<NodeT*> >(*this, NewBB); 548 } 549 550 /// print - Convert to human readable form 551 /// 552 void print(raw_ostream &o) const { 553 o << "=============================--------------------------------\n"; 554 if (this->isPostDominator()) 555 o << "Inorder PostDominator Tree: "; 556 else 557 o << "Inorder Dominator Tree: "; 558 if (!this->DFSInfoValid) 559 o << "DFSNumbers invalid: " << SlowQueries << " slow queries."; 560 o << "\n"; 561 562 // The postdom tree can have a null root if there are no returns. 563 if (getRootNode()) 564 PrintDomTree<NodeT>(getRootNode(), o, 1); 565 } 566 567protected: 568 template<class GraphT> 569 friend void Compress(DominatorTreeBase<typename GraphT::NodeType>& DT, 570 typename GraphT::NodeType* VIn); 571 572 template<class GraphT> 573 friend typename GraphT::NodeType* Eval( 574 DominatorTreeBase<typename GraphT::NodeType>& DT, 575 typename GraphT::NodeType* V); 576 577 template<class GraphT> 578 friend void Link(DominatorTreeBase<typename GraphT::NodeType>& DT, 579 unsigned DFSNumV, typename GraphT::NodeType* W, 580 typename DominatorTreeBase<typename GraphT::NodeType>::InfoRec &WInfo); 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 typename DomTreeNodeMapType::iterator I = this->DomTreeNodes.find(BB); 637 if (I != this->DomTreeNodes.end() && I->second) 638 return I->second; 639 640 // Haven't calculated this node yet? Get or calculate the node for the 641 // immediate dominator. 642 NodeT *IDom = getIDom(BB); 643 644 assert(IDom || this->DomTreeNodes[NULL]); 645 DomTreeNodeBase<NodeT> *IDomNode = getNodeForBlock(IDom); 646 647 // Add a new tree node for this BasicBlock, and link it as a child of 648 // IDomNode 649 DomTreeNodeBase<NodeT> *C = new DomTreeNodeBase<NodeT>(BB, IDomNode); 650 return this->DomTreeNodes[BB] = IDomNode->addChild(C); 651 } 652 653 inline NodeT *getIDom(NodeT *BB) const { 654 typename DenseMap<NodeT*, NodeT*>::const_iterator I = IDoms.find(BB); 655 return I != IDoms.end() ? I->second : 0; 656 } 657 658 inline void addRoot(NodeT* BB) { 659 this->Roots.push_back(BB); 660 } 661 662public: 663 /// recalculate - compute a dominator tree for the given function 664 template<class FT> 665 void recalculate(FT& F) { 666 reset(); 667 this->Vertex.push_back(0); 668 669 if (!this->IsPostDominators) { 670 // Initialize root 671 this->Roots.push_back(&F.front()); 672 this->IDoms[&F.front()] = 0; 673 this->DomTreeNodes[&F.front()] = 0; 674 675 Calculate<FT, NodeT*>(*this, F); 676 } else { 677 // Initialize the roots list 678 for (typename FT::iterator I = F.begin(), E = F.end(); I != E; ++I) { 679 if (std::distance(GraphTraits<FT*>::child_begin(I), 680 GraphTraits<FT*>::child_end(I)) == 0) 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 693EXTERN_TEMPLATE_INSTANTIATION(class DominatorTreeBase<BasicBlock>); 694 695//===------------------------------------- 696/// DominatorTree Class - Concrete subclass of DominatorTreeBase that is used to 697/// compute a normal dominator tree. 698/// 699class DominatorTree : public FunctionPass { 700public: 701 static char ID; // Pass ID, replacement for typeid 702 DominatorTreeBase<BasicBlock>* DT; 703 704 DominatorTree() : FunctionPass(ID) { 705 initializeDominatorTreePass(*PassRegistry::getPassRegistry()); 706 DT = new DominatorTreeBase<BasicBlock>(false); 707 } 708 709 ~DominatorTree() { 710 delete DT; 711 } 712 713 DominatorTreeBase<BasicBlock>& getBase() { return *DT; } 714 715 /// getRoots - Return the root blocks of the current CFG. This may include 716 /// multiple blocks if we are computing post dominators. For forward 717 /// dominators, this will always be a single block (the entry node). 718 /// 719 inline const std::vector<BasicBlock*> &getRoots() const { 720 return DT->getRoots(); 721 } 722 723 inline BasicBlock *getRoot() const { 724 return DT->getRoot(); 725 } 726 727 inline DomTreeNode *getRootNode() const { 728 return DT->getRootNode(); 729 } 730 731 /// compare - Return false if the other dominator tree matches this 732 /// dominator tree. Otherwise return true. 733 inline bool compare(DominatorTree &Other) const { 734 DomTreeNode *R = getRootNode(); 735 DomTreeNode *OtherR = Other.getRootNode(); 736 737 if (!R || !OtherR || R->getBlock() != OtherR->getBlock()) 738 return true; 739 740 if (DT->compare(Other.getBase())) 741 return true; 742 743 return false; 744 } 745 746 virtual bool runOnFunction(Function &F); 747 748 virtual void verifyAnalysis() const; 749 750 virtual void getAnalysisUsage(AnalysisUsage &AU) const { 751 AU.setPreservesAll(); 752 } 753 754 inline bool dominates(const DomTreeNode* A, const DomTreeNode* B) const { 755 return DT->dominates(A, B); 756 } 757 758 inline bool dominates(const BasicBlock* A, const BasicBlock* B) const { 759 return DT->dominates(A, B); 760 } 761 762 // dominates - Return true if A dominates B. This performs the 763 // special checks necessary if A and B are in the same basic block. 764 bool dominates(const Instruction *A, const Instruction *B) const; 765 766 bool properlyDominates(const DomTreeNode *A, const DomTreeNode *B) const { 767 return DT->properlyDominates(A, B); 768 } 769 770 bool properlyDominates(const BasicBlock *A, const BasicBlock *B) const { 771 return DT->properlyDominates(A, B); 772 } 773 774 /// findNearestCommonDominator - Find nearest common dominator basic block 775 /// for basic block A and B. If there is no such block then return NULL. 776 inline BasicBlock *findNearestCommonDominator(BasicBlock *A, BasicBlock *B) { 777 return DT->findNearestCommonDominator(A, B); 778 } 779 780 inline const BasicBlock *findNearestCommonDominator(const BasicBlock *A, 781 const BasicBlock *B) { 782 return DT->findNearestCommonDominator(A, B); 783 } 784 785 inline DomTreeNode *operator[](BasicBlock *BB) const { 786 return DT->getNode(BB); 787 } 788 789 /// getNode - return the (Post)DominatorTree node for the specified basic 790 /// block. This is the same as using operator[] on this class. 791 /// 792 inline DomTreeNode *getNode(BasicBlock *BB) const { 793 return DT->getNode(BB); 794 } 795 796 /// addNewBlock - Add a new node to the dominator tree information. This 797 /// creates a new node as a child of DomBB dominator node,linking it into 798 /// the children list of the immediate dominator. 799 inline DomTreeNode *addNewBlock(BasicBlock *BB, BasicBlock *DomBB) { 800 return DT->addNewBlock(BB, DomBB); 801 } 802 803 /// changeImmediateDominator - This method is used to update the dominator 804 /// tree information when a node's immediate dominator changes. 805 /// 806 inline void changeImmediateDominator(BasicBlock *N, BasicBlock* NewIDom) { 807 DT->changeImmediateDominator(N, NewIDom); 808 } 809 810 inline void changeImmediateDominator(DomTreeNode *N, DomTreeNode* NewIDom) { 811 DT->changeImmediateDominator(N, NewIDom); 812 } 813 814 /// eraseNode - Removes a node from the dominator tree. Block must not 815 /// dominate any other blocks. Removes node from its immediate dominator's 816 /// children list. Deletes dominator node associated with basic block BB. 817 inline void eraseNode(BasicBlock *BB) { 818 DT->eraseNode(BB); 819 } 820 821 /// splitBlock - BB is split and now it has one successor. Update dominator 822 /// tree to reflect this change. 823 inline void splitBlock(BasicBlock* NewBB) { 824 DT->splitBlock(NewBB); 825 } 826 827 bool isReachableFromEntry(const BasicBlock* A) { 828 return DT->isReachableFromEntry(A); 829 } 830 831 832 virtual void releaseMemory() { 833 DT->releaseMemory(); 834 } 835 836 virtual void print(raw_ostream &OS, const Module* M= 0) const; 837}; 838 839//===------------------------------------- 840/// DominatorTree GraphTraits specialization so the DominatorTree can be 841/// iterable by generic graph iterators. 842/// 843template <> struct GraphTraits<DomTreeNode*> { 844 typedef DomTreeNode NodeType; 845 typedef NodeType::iterator ChildIteratorType; 846 847 static NodeType *getEntryNode(NodeType *N) { 848 return N; 849 } 850 static inline ChildIteratorType child_begin(NodeType *N) { 851 return N->begin(); 852 } 853 static inline ChildIteratorType child_end(NodeType *N) { 854 return N->end(); 855 } 856 857 typedef df_iterator<DomTreeNode*> nodes_iterator; 858 859 static nodes_iterator nodes_begin(DomTreeNode *N) { 860 return df_begin(getEntryNode(N)); 861 } 862 863 static nodes_iterator nodes_end(DomTreeNode *N) { 864 return df_end(getEntryNode(N)); 865 } 866}; 867 868template <> struct GraphTraits<DominatorTree*> 869 : public GraphTraits<DomTreeNode*> { 870 static NodeType *getEntryNode(DominatorTree *DT) { 871 return DT->getRootNode(); 872 } 873 874 static nodes_iterator nodes_begin(DominatorTree *N) { 875 return df_begin(getEntryNode(N)); 876 } 877 878 static nodes_iterator nodes_end(DominatorTree *N) { 879 return df_end(getEntryNode(N)); 880 } 881}; 882 883 884} // End llvm namespace 885 886#endif 887