Dominators.h revision cbf39b58919497f711de24fa687b044805f58ae7
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 std::vector<NodeT*> Bucket; 204 205 InfoRec() : DFSNum(0), Semi(0), Size(0), Label(0), Child(0), Parent(0), 206 Ancestor(0) {} 207 }; 208 209 DenseMap<NodeT*, NodeT*> IDoms; 210 211 // Vertex - Map the DFS number to the BasicBlock* 212 std::vector<NodeT*> Vertex; 213 214 // Info - Collection of information used during the computation of idoms. 215 DenseMap<NodeT*, InfoRec> Info; 216 217 void reset() { 218 for (typename DomTreeNodeMapType::iterator I = this->DomTreeNodes.begin(), 219 E = DomTreeNodes.end(); I != E; ++I) 220 delete I->second; 221 DomTreeNodes.clear(); 222 IDoms.clear(); 223 this->Roots.clear(); 224 Vertex.clear(); 225 RootNode = 0; 226 } 227 228 // NewBB is split and now it has one successor. Update dominator tree to 229 // reflect this change. 230 template<class N, class GraphT> 231 void Split(DominatorTreeBase<typename GraphT::NodeType>& DT, 232 typename GraphT::NodeType* NewBB) { 233 assert(std::distance(GraphT::child_begin(NewBB), 234 GraphT::child_end(NewBB)) == 1 && 235 "NewBB should have a single successor!"); 236 typename GraphT::NodeType* NewBBSucc = *GraphT::child_begin(NewBB); 237 238 std::vector<typename GraphT::NodeType*> PredBlocks; 239 typedef GraphTraits<Inverse<N> > InvTraits; 240 for (typename InvTraits::ChildIteratorType PI = 241 InvTraits::child_begin(NewBB), 242 PE = InvTraits::child_end(NewBB); PI != PE; ++PI) 243 PredBlocks.push_back(*PI); 244 245 assert(!PredBlocks.empty() && "No predblocks?"); 246 247 bool NewBBDominatesNewBBSucc = true; 248 for (typename InvTraits::ChildIteratorType PI = 249 InvTraits::child_begin(NewBBSucc), 250 E = InvTraits::child_end(NewBBSucc); PI != E; ++PI) { 251 typename InvTraits::NodeType *ND = *PI; 252 if (ND != NewBB && !DT.dominates(NewBBSucc, ND) && 253 DT.isReachableFromEntry(ND)) { 254 NewBBDominatesNewBBSucc = false; 255 break; 256 } 257 } 258 259 // Find NewBB's immediate dominator and create new dominator tree node for 260 // NewBB. 261 NodeT *NewBBIDom = 0; 262 unsigned i = 0; 263 for (i = 0; i < PredBlocks.size(); ++i) 264 if (DT.isReachableFromEntry(PredBlocks[i])) { 265 NewBBIDom = PredBlocks[i]; 266 break; 267 } 268 269 // It's possible that none of the predecessors of NewBB are reachable; 270 // in that case, NewBB itself is unreachable, so nothing needs to be 271 // changed. 272 if (!NewBBIDom) 273 return; 274 275 for (i = i + 1; i < PredBlocks.size(); ++i) { 276 if (DT.isReachableFromEntry(PredBlocks[i])) 277 NewBBIDom = DT.findNearestCommonDominator(NewBBIDom, PredBlocks[i]); 278 } 279 280 // Create the new dominator tree node... and set the idom of NewBB. 281 DomTreeNodeBase<NodeT> *NewBBNode = DT.addNewBlock(NewBB, NewBBIDom); 282 283 // If NewBB strictly dominates other blocks, then it is now the immediate 284 // dominator of NewBBSucc. Update the dominator tree as appropriate. 285 if (NewBBDominatesNewBBSucc) { 286 DomTreeNodeBase<NodeT> *NewBBSuccNode = DT.getNode(NewBBSucc); 287 DT.changeImmediateDominator(NewBBSuccNode, NewBBNode); 288 } 289 } 290 291public: 292 explicit DominatorTreeBase(bool isPostDom) 293 : DominatorBase<NodeT>(isPostDom), DFSInfoValid(false), SlowQueries(0) {} 294 virtual ~DominatorTreeBase() { reset(); } 295 296 // FIXME: Should remove this 297 virtual bool runOnFunction(Function &F) { return false; } 298 299 /// compare - Return false if the other dominator tree base matches this 300 /// dominator tree base. Otherwise return true. 301 bool compare(DominatorTreeBase &Other) const { 302 303 const DomTreeNodeMapType &OtherDomTreeNodes = Other.DomTreeNodes; 304 if (DomTreeNodes.size() != OtherDomTreeNodes.size()) 305 return true; 306 307 for (typename DomTreeNodeMapType::const_iterator 308 I = this->DomTreeNodes.begin(), 309 E = this->DomTreeNodes.end(); I != E; ++I) { 310 NodeT *BB = I->first; 311 typename DomTreeNodeMapType::const_iterator OI = OtherDomTreeNodes.find(BB); 312 if (OI == OtherDomTreeNodes.end()) 313 return true; 314 315 DomTreeNodeBase<NodeT>* MyNd = I->second; 316 DomTreeNodeBase<NodeT>* OtherNd = OI->second; 317 318 if (MyNd->compare(OtherNd)) 319 return true; 320 } 321 322 return false; 323 } 324 325 virtual void releaseMemory() { reset(); } 326 327 /// getNode - return the (Post)DominatorTree node for the specified basic 328 /// block. This is the same as using operator[] on this class. 329 /// 330 inline DomTreeNodeBase<NodeT> *getNode(NodeT *BB) const { 331 typename DomTreeNodeMapType::const_iterator I = DomTreeNodes.find(BB); 332 return I != DomTreeNodes.end() ? I->second : 0; 333 } 334 335 /// getRootNode - This returns the entry node for the CFG of the function. If 336 /// this tree represents the post-dominance relations for a function, however, 337 /// this root may be a node with the block == NULL. This is the case when 338 /// there are multiple exit nodes from a particular function. Consumers of 339 /// post-dominance information must be capable of dealing with this 340 /// possibility. 341 /// 342 DomTreeNodeBase<NodeT> *getRootNode() { return RootNode; } 343 const DomTreeNodeBase<NodeT> *getRootNode() const { return RootNode; } 344 345 /// properlyDominates - Returns true iff this dominates N and this != N. 346 /// Note that this is not a constant time operation! 347 /// 348 bool properlyDominates(const DomTreeNodeBase<NodeT> *A, 349 const DomTreeNodeBase<NodeT> *B) const { 350 if (A == 0 || B == 0) return false; 351 return dominatedBySlowTreeWalk(A, B); 352 } 353 354 inline bool properlyDominates(const NodeT *A, const NodeT *B) { 355 if (A == B) 356 return false; 357 358 // Cast away the const qualifiers here. This is ok since 359 // this function doesn't actually return the values returned 360 // from getNode. 361 return properlyDominates(getNode(const_cast<NodeT *>(A)), 362 getNode(const_cast<NodeT *>(B))); 363 } 364 365 bool dominatedBySlowTreeWalk(const DomTreeNodeBase<NodeT> *A, 366 const DomTreeNodeBase<NodeT> *B) const { 367 const DomTreeNodeBase<NodeT> *IDom; 368 if (A == 0 || B == 0) return false; 369 while ((IDom = B->getIDom()) != 0 && IDom != A && IDom != B) 370 B = IDom; // Walk up the tree 371 return IDom != 0; 372 } 373 374 375 /// isReachableFromEntry - Return true if A is dominated by the entry 376 /// block of the function containing it. 377 bool isReachableFromEntry(const NodeT* A) { 378 assert(!this->isPostDominator() && 379 "This is not implemented for post dominators"); 380 return dominates(&A->getParent()->front(), A); 381 } 382 383 /// dominates - Returns true iff A dominates B. Note that this is not a 384 /// constant time operation! 385 /// 386 inline bool dominates(const DomTreeNodeBase<NodeT> *A, 387 const DomTreeNodeBase<NodeT> *B) { 388 if (B == A) 389 return true; // A node trivially dominates itself. 390 391 if (A == 0 || B == 0) 392 return false; 393 394 // Compare the result of the tree walk and the dfs numbers, if expensive 395 // checks are enabled. 396#ifdef XDEBUG 397 assert((!DFSInfoValid || 398 (dominatedBySlowTreeWalk(A, B) == B->DominatedBy(A))) && 399 "Tree walk disagrees with dfs numbers!"); 400#endif 401 402 if (DFSInfoValid) 403 return B->DominatedBy(A); 404 405 // If we end up with too many slow queries, just update the 406 // DFS numbers on the theory that we are going to keep querying. 407 SlowQueries++; 408 if (SlowQueries > 32) { 409 updateDFSNumbers(); 410 return B->DominatedBy(A); 411 } 412 413 return dominatedBySlowTreeWalk(A, B); 414 } 415 416 inline bool dominates(const NodeT *A, const NodeT *B) { 417 if (A == B) 418 return true; 419 420 // Cast away the const qualifiers here. This is ok since 421 // this function doesn't actually return the values returned 422 // from getNode. 423 return dominates(getNode(const_cast<NodeT *>(A)), 424 getNode(const_cast<NodeT *>(B))); 425 } 426 427 NodeT *getRoot() const { 428 assert(this->Roots.size() == 1 && "Should always have entry node!"); 429 return this->Roots[0]; 430 } 431 432 /// findNearestCommonDominator - Find nearest common dominator basic block 433 /// for basic block A and B. If there is no such block then return NULL. 434 NodeT *findNearestCommonDominator(NodeT *A, NodeT *B) { 435 assert(A->getParent() == B->getParent() && 436 "Two blocks are not in same function"); 437 438 // If either A or B is a entry block then it is nearest common dominator 439 // (for forward-dominators). 440 if (!this->isPostDominator()) { 441 NodeT &Entry = A->getParent()->front(); 442 if (A == &Entry || B == &Entry) 443 return &Entry; 444 } 445 446 // If B dominates A then B is nearest common dominator. 447 if (dominates(B, A)) 448 return B; 449 450 // If A dominates B then A is nearest common dominator. 451 if (dominates(A, B)) 452 return A; 453 454 DomTreeNodeBase<NodeT> *NodeA = getNode(A); 455 DomTreeNodeBase<NodeT> *NodeB = getNode(B); 456 457 // Collect NodeA dominators set. 458 SmallPtrSet<DomTreeNodeBase<NodeT>*, 16> NodeADoms; 459 NodeADoms.insert(NodeA); 460 DomTreeNodeBase<NodeT> *IDomA = NodeA->getIDom(); 461 while (IDomA) { 462 NodeADoms.insert(IDomA); 463 IDomA = IDomA->getIDom(); 464 } 465 466 // Walk NodeB immediate dominators chain and find common dominator node. 467 DomTreeNodeBase<NodeT> *IDomB = NodeB->getIDom(); 468 while (IDomB) { 469 if (NodeADoms.count(IDomB) != 0) 470 return IDomB->getBlock(); 471 472 IDomB = IDomB->getIDom(); 473 } 474 475 return NULL; 476 } 477 478 const NodeT *findNearestCommonDominator(const NodeT *A, const NodeT *B) { 479 // Cast away the const qualifiers here. This is ok since 480 // const is re-introduced on the return type. 481 return findNearestCommonDominator(const_cast<NodeT *>(A), 482 const_cast<NodeT *>(B)); 483 } 484 485 //===--------------------------------------------------------------------===// 486 // API to update (Post)DominatorTree information based on modifications to 487 // the CFG... 488 489 /// addNewBlock - Add a new node to the dominator tree information. This 490 /// creates a new node as a child of DomBB dominator node,linking it into 491 /// the children list of the immediate dominator. 492 DomTreeNodeBase<NodeT> *addNewBlock(NodeT *BB, NodeT *DomBB) { 493 assert(getNode(BB) == 0 && "Block already in dominator tree!"); 494 DomTreeNodeBase<NodeT> *IDomNode = getNode(DomBB); 495 assert(IDomNode && "Not immediate dominator specified for block!"); 496 DFSInfoValid = false; 497 return DomTreeNodes[BB] = 498 IDomNode->addChild(new DomTreeNodeBase<NodeT>(BB, IDomNode)); 499 } 500 501 /// changeImmediateDominator - This method is used to update the dominator 502 /// tree information when a node's immediate dominator changes. 503 /// 504 void changeImmediateDominator(DomTreeNodeBase<NodeT> *N, 505 DomTreeNodeBase<NodeT> *NewIDom) { 506 assert(N && NewIDom && "Cannot change null node pointers!"); 507 DFSInfoValid = false; 508 N->setIDom(NewIDom); 509 } 510 511 void changeImmediateDominator(NodeT *BB, NodeT *NewBB) { 512 changeImmediateDominator(getNode(BB), getNode(NewBB)); 513 } 514 515 /// eraseNode - Removes a node from the dominator tree. Block must not 516 /// dominate any other blocks. Removes node from its immediate dominator's 517 /// children list. Deletes dominator node associated with basic block BB. 518 void eraseNode(NodeT *BB) { 519 DomTreeNodeBase<NodeT> *Node = getNode(BB); 520 assert(Node && "Removing node that isn't in dominator tree."); 521 assert(Node->getChildren().empty() && "Node is not a leaf node."); 522 523 // Remove node from immediate dominator's children list. 524 DomTreeNodeBase<NodeT> *IDom = Node->getIDom(); 525 if (IDom) { 526 typename std::vector<DomTreeNodeBase<NodeT>*>::iterator I = 527 std::find(IDom->Children.begin(), IDom->Children.end(), Node); 528 assert(I != IDom->Children.end() && 529 "Not in immediate dominator children set!"); 530 // I am no longer your child... 531 IDom->Children.erase(I); 532 } 533 534 DomTreeNodes.erase(BB); 535 delete Node; 536 } 537 538 /// removeNode - Removes a node from the dominator tree. Block must not 539 /// dominate any other blocks. Invalidates any node pointing to removed 540 /// block. 541 void removeNode(NodeT *BB) { 542 assert(getNode(BB) && "Removing node that isn't in dominator tree."); 543 DomTreeNodes.erase(BB); 544 } 545 546 /// splitBlock - BB is split and now it has one successor. Update dominator 547 /// tree to reflect this change. 548 void splitBlock(NodeT* NewBB) { 549 if (this->IsPostDominators) 550 this->Split<Inverse<NodeT*>, GraphTraits<Inverse<NodeT*> > >(*this, NewBB); 551 else 552 this->Split<NodeT*, GraphTraits<NodeT*> >(*this, NewBB); 553 } 554 555 /// print - Convert to human readable form 556 /// 557 void print(raw_ostream &o) const { 558 o << "=============================--------------------------------\n"; 559 if (this->isPostDominator()) 560 o << "Inorder PostDominator Tree: "; 561 else 562 o << "Inorder Dominator Tree: "; 563 if (!this->DFSInfoValid) 564 o << "DFSNumbers invalid: " << SlowQueries << " slow queries."; 565 o << "\n"; 566 567 // The postdom tree can have a null root if there are no returns. 568 if (getRootNode()) 569 PrintDomTree<NodeT>(getRootNode(), o, 1); 570 } 571 572protected: 573 template<class GraphT> 574 friend void Compress(DominatorTreeBase<typename GraphT::NodeType>& DT, 575 typename GraphT::NodeType* VIn); 576 577 template<class GraphT> 578 friend typename GraphT::NodeType* Eval( 579 DominatorTreeBase<typename GraphT::NodeType>& DT, 580 typename GraphT::NodeType* V); 581 582 template<class GraphT> 583 friend void Link(DominatorTreeBase<typename GraphT::NodeType>& DT, 584 unsigned DFSNumV, typename GraphT::NodeType* W, 585 typename DominatorTreeBase<typename GraphT::NodeType>::InfoRec &WInfo); 586 587 template<class GraphT> 588 friend unsigned DFSPass(DominatorTreeBase<typename GraphT::NodeType>& DT, 589 typename GraphT::NodeType* V, 590 unsigned N); 591 592 template<class FuncT, class N> 593 friend void Calculate(DominatorTreeBase<typename GraphTraits<N>::NodeType>& DT, 594 FuncT& F); 595 596 /// updateDFSNumbers - Assign In and Out numbers to the nodes while walking 597 /// dominator tree in dfs order. 598 void updateDFSNumbers() { 599 unsigned DFSNum = 0; 600 601 SmallVector<std::pair<DomTreeNodeBase<NodeT>*, 602 typename DomTreeNodeBase<NodeT>::iterator>, 32> WorkStack; 603 604 DomTreeNodeBase<NodeT> *ThisRoot = getRootNode(); 605 606 if (!ThisRoot) 607 return; 608 609 // Even in the case of multiple exits that form the post dominator root 610 // nodes, do not iterate over all exits, but start from the virtual root 611 // node. Otherwise bbs, that are not post dominated by any exit but by the 612 // virtual root node, will never be assigned a DFS number. 613 WorkStack.push_back(std::make_pair(ThisRoot, ThisRoot->begin())); 614 ThisRoot->DFSNumIn = DFSNum++; 615 616 while (!WorkStack.empty()) { 617 DomTreeNodeBase<NodeT> *Node = WorkStack.back().first; 618 typename DomTreeNodeBase<NodeT>::iterator ChildIt = 619 WorkStack.back().second; 620 621 // If we visited all of the children of this node, "recurse" back up the 622 // stack setting the DFOutNum. 623 if (ChildIt == Node->end()) { 624 Node->DFSNumOut = DFSNum++; 625 WorkStack.pop_back(); 626 } else { 627 // Otherwise, recursively visit this child. 628 DomTreeNodeBase<NodeT> *Child = *ChildIt; 629 ++WorkStack.back().second; 630 631 WorkStack.push_back(std::make_pair(Child, Child->begin())); 632 Child->DFSNumIn = DFSNum++; 633 } 634 } 635 636 SlowQueries = 0; 637 DFSInfoValid = true; 638 } 639 640 DomTreeNodeBase<NodeT> *getNodeForBlock(NodeT *BB) { 641 typename DomTreeNodeMapType::iterator I = this->DomTreeNodes.find(BB); 642 if (I != this->DomTreeNodes.end() && I->second) 643 return I->second; 644 645 // Haven't calculated this node yet? Get or calculate the node for the 646 // immediate dominator. 647 NodeT *IDom = getIDom(BB); 648 649 assert(IDom || this->DomTreeNodes[NULL]); 650 DomTreeNodeBase<NodeT> *IDomNode = getNodeForBlock(IDom); 651 652 // Add a new tree node for this BasicBlock, and link it as a child of 653 // IDomNode 654 DomTreeNodeBase<NodeT> *C = new DomTreeNodeBase<NodeT>(BB, IDomNode); 655 return this->DomTreeNodes[BB] = IDomNode->addChild(C); 656 } 657 658 inline NodeT *getIDom(NodeT *BB) const { 659 typename DenseMap<NodeT*, NodeT*>::const_iterator I = IDoms.find(BB); 660 return I != IDoms.end() ? I->second : 0; 661 } 662 663 inline void addRoot(NodeT* BB) { 664 this->Roots.push_back(BB); 665 } 666 667public: 668 /// recalculate - compute a dominator tree for the given function 669 template<class FT> 670 void recalculate(FT& F) { 671 reset(); 672 this->Vertex.push_back(0); 673 674 if (!this->IsPostDominators) { 675 // Initialize root 676 this->Roots.push_back(&F.front()); 677 this->IDoms[&F.front()] = 0; 678 this->DomTreeNodes[&F.front()] = 0; 679 680 Calculate<FT, NodeT*>(*this, F); 681 } else { 682 // Initialize the roots list 683 for (typename FT::iterator I = F.begin(), E = F.end(); I != E; ++I) { 684 if (std::distance(GraphTraits<FT*>::child_begin(I), 685 GraphTraits<FT*>::child_end(I)) == 0) 686 addRoot(I); 687 688 // Prepopulate maps so that we don't get iterator invalidation issues later. 689 this->IDoms[I] = 0; 690 this->DomTreeNodes[I] = 0; 691 } 692 693 Calculate<FT, Inverse<NodeT*> >(*this, F); 694 } 695 } 696}; 697 698EXTERN_TEMPLATE_INSTANTIATION(class DominatorTreeBase<BasicBlock>); 699 700//===------------------------------------- 701/// DominatorTree Class - Concrete subclass of DominatorTreeBase that is used to 702/// compute a normal dominator tree. 703/// 704class DominatorTree : public FunctionPass { 705public: 706 static char ID; // Pass ID, replacement for typeid 707 DominatorTreeBase<BasicBlock>* DT; 708 709 DominatorTree() : FunctionPass(ID) { 710 initializeDominatorTreePass(*PassRegistry::getPassRegistry()); 711 DT = new DominatorTreeBase<BasicBlock>(false); 712 } 713 714 ~DominatorTree() { 715 delete DT; 716 } 717 718 DominatorTreeBase<BasicBlock>& getBase() { return *DT; } 719 720 /// getRoots - Return the root blocks of the current CFG. This may include 721 /// multiple blocks if we are computing post dominators. For forward 722 /// dominators, this will always be a single block (the entry node). 723 /// 724 inline const std::vector<BasicBlock*> &getRoots() const { 725 return DT->getRoots(); 726 } 727 728 inline BasicBlock *getRoot() const { 729 return DT->getRoot(); 730 } 731 732 inline DomTreeNode *getRootNode() const { 733 return DT->getRootNode(); 734 } 735 736 /// compare - Return false if the other dominator tree matches this 737 /// dominator tree. Otherwise return true. 738 inline bool compare(DominatorTree &Other) const { 739 DomTreeNode *R = getRootNode(); 740 DomTreeNode *OtherR = Other.getRootNode(); 741 742 if (!R || !OtherR || R->getBlock() != OtherR->getBlock()) 743 return true; 744 745 if (DT->compare(Other.getBase())) 746 return true; 747 748 return false; 749 } 750 751 virtual bool runOnFunction(Function &F); 752 753 virtual void verifyAnalysis() const; 754 755 virtual void getAnalysisUsage(AnalysisUsage &AU) const { 756 AU.setPreservesAll(); 757 } 758 759 inline bool dominates(const DomTreeNode* A, const DomTreeNode* B) const { 760 return DT->dominates(A, B); 761 } 762 763 inline bool dominates(const BasicBlock* A, const BasicBlock* B) const { 764 return DT->dominates(A, B); 765 } 766 767 // dominates - Return true if A dominates B. This performs the 768 // special checks necessary if A and B are in the same basic block. 769 bool dominates(const Instruction *A, const Instruction *B) const; 770 771 bool properlyDominates(const DomTreeNode *A, const DomTreeNode *B) const { 772 return DT->properlyDominates(A, B); 773 } 774 775 bool properlyDominates(const BasicBlock *A, const BasicBlock *B) const { 776 return DT->properlyDominates(A, B); 777 } 778 779 /// findNearestCommonDominator - Find nearest common dominator basic block 780 /// for basic block A and B. If there is no such block then return NULL. 781 inline BasicBlock *findNearestCommonDominator(BasicBlock *A, BasicBlock *B) { 782 return DT->findNearestCommonDominator(A, B); 783 } 784 785 inline const BasicBlock *findNearestCommonDominator(const BasicBlock *A, 786 const BasicBlock *B) { 787 return DT->findNearestCommonDominator(A, B); 788 } 789 790 inline DomTreeNode *operator[](BasicBlock *BB) const { 791 return DT->getNode(BB); 792 } 793 794 /// getNode - return the (Post)DominatorTree node for the specified basic 795 /// block. This is the same as using operator[] on this class. 796 /// 797 inline DomTreeNode *getNode(BasicBlock *BB) const { 798 return DT->getNode(BB); 799 } 800 801 /// addNewBlock - Add a new node to the dominator tree information. This 802 /// creates a new node as a child of DomBB dominator node,linking it into 803 /// the children list of the immediate dominator. 804 inline DomTreeNode *addNewBlock(BasicBlock *BB, BasicBlock *DomBB) { 805 return DT->addNewBlock(BB, DomBB); 806 } 807 808 /// changeImmediateDominator - This method is used to update the dominator 809 /// tree information when a node's immediate dominator changes. 810 /// 811 inline void changeImmediateDominator(BasicBlock *N, BasicBlock* NewIDom) { 812 DT->changeImmediateDominator(N, NewIDom); 813 } 814 815 inline void changeImmediateDominator(DomTreeNode *N, DomTreeNode* NewIDom) { 816 DT->changeImmediateDominator(N, NewIDom); 817 } 818 819 /// eraseNode - Removes a node from the dominator tree. Block must not 820 /// dominate any other blocks. Removes node from its immediate dominator's 821 /// children list. Deletes dominator node associated with basic block BB. 822 inline void eraseNode(BasicBlock *BB) { 823 DT->eraseNode(BB); 824 } 825 826 /// splitBlock - BB is split and now it has one successor. Update dominator 827 /// tree to reflect this change. 828 inline void splitBlock(BasicBlock* NewBB) { 829 DT->splitBlock(NewBB); 830 } 831 832 bool isReachableFromEntry(const BasicBlock* A) { 833 return DT->isReachableFromEntry(A); 834 } 835 836 837 virtual void releaseMemory() { 838 DT->releaseMemory(); 839 } 840 841 virtual void print(raw_ostream &OS, const Module* M= 0) const; 842}; 843 844//===------------------------------------- 845/// DominatorTree GraphTraits specialization so the DominatorTree can be 846/// iterable by generic graph iterators. 847/// 848template <> struct GraphTraits<DomTreeNode*> { 849 typedef DomTreeNode NodeType; 850 typedef NodeType::iterator ChildIteratorType; 851 852 static NodeType *getEntryNode(NodeType *N) { 853 return N; 854 } 855 static inline ChildIteratorType child_begin(NodeType *N) { 856 return N->begin(); 857 } 858 static inline ChildIteratorType child_end(NodeType *N) { 859 return N->end(); 860 } 861 862 typedef df_iterator<DomTreeNode*> nodes_iterator; 863 864 static nodes_iterator nodes_begin(DomTreeNode *N) { 865 return df_begin(getEntryNode(N)); 866 } 867 868 static nodes_iterator nodes_end(DomTreeNode *N) { 869 return df_end(getEntryNode(N)); 870 } 871}; 872 873template <> struct GraphTraits<DominatorTree*> 874 : public GraphTraits<DomTreeNode*> { 875 static NodeType *getEntryNode(DominatorTree *DT) { 876 return DT->getRootNode(); 877 } 878 879 static nodes_iterator nodes_begin(DominatorTree *N) { 880 return df_begin(getEntryNode(N)); 881 } 882 883 static nodes_iterator nodes_end(DominatorTree *N) { 884 return df_end(getEntryNode(N)); 885 } 886}; 887 888 889} // End llvm namespace 890 891#endif 892