Dominators.h revision b5c26ef9da16052597d59a412eaae32098aa1be0
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 Parent; 199 unsigned Semi; 200 NodeT *Label; 201 202 InfoRec() : DFSNum(0), Parent(0), Semi(0), Label(0) {} 203 }; 204 205 DenseMap<NodeT*, NodeT*> IDoms; 206 207 // Vertex - Map the DFS number to the BasicBlock* 208 std::vector<NodeT*> Vertex; 209 210 // Info - Collection of information used during the computation of idoms. 211 DenseMap<NodeT*, InfoRec> Info; 212 213 void reset() { 214 for (typename DomTreeNodeMapType::iterator I = this->DomTreeNodes.begin(), 215 E = DomTreeNodes.end(); I != E; ++I) 216 delete I->second; 217 DomTreeNodes.clear(); 218 IDoms.clear(); 219 this->Roots.clear(); 220 Vertex.clear(); 221 RootNode = 0; 222 } 223 224 // NewBB is split and now it has one successor. Update dominator tree to 225 // reflect this change. 226 template<class N, class GraphT> 227 void Split(DominatorTreeBase<typename GraphT::NodeType>& DT, 228 typename GraphT::NodeType* NewBB) { 229 assert(std::distance(GraphT::child_begin(NewBB), 230 GraphT::child_end(NewBB)) == 1 && 231 "NewBB should have a single successor!"); 232 typename GraphT::NodeType* NewBBSucc = *GraphT::child_begin(NewBB); 233 234 std::vector<typename GraphT::NodeType*> PredBlocks; 235 typedef GraphTraits<Inverse<N> > InvTraits; 236 for (typename InvTraits::ChildIteratorType PI = 237 InvTraits::child_begin(NewBB), 238 PE = InvTraits::child_end(NewBB); PI != PE; ++PI) 239 PredBlocks.push_back(*PI); 240 241 assert(!PredBlocks.empty() && "No predblocks?"); 242 243 bool NewBBDominatesNewBBSucc = true; 244 for (typename InvTraits::ChildIteratorType PI = 245 InvTraits::child_begin(NewBBSucc), 246 E = InvTraits::child_end(NewBBSucc); PI != E; ++PI) { 247 typename InvTraits::NodeType *ND = *PI; 248 if (ND != NewBB && !DT.dominates(NewBBSucc, ND) && 249 DT.isReachableFromEntry(ND)) { 250 NewBBDominatesNewBBSucc = false; 251 break; 252 } 253 } 254 255 // Find NewBB's immediate dominator and create new dominator tree node for 256 // NewBB. 257 NodeT *NewBBIDom = 0; 258 unsigned i = 0; 259 for (i = 0; i < PredBlocks.size(); ++i) 260 if (DT.isReachableFromEntry(PredBlocks[i])) { 261 NewBBIDom = PredBlocks[i]; 262 break; 263 } 264 265 // It's possible that none of the predecessors of NewBB are reachable; 266 // in that case, NewBB itself is unreachable, so nothing needs to be 267 // changed. 268 if (!NewBBIDom) 269 return; 270 271 for (i = i + 1; i < PredBlocks.size(); ++i) { 272 if (DT.isReachableFromEntry(PredBlocks[i])) 273 NewBBIDom = DT.findNearestCommonDominator(NewBBIDom, PredBlocks[i]); 274 } 275 276 // Create the new dominator tree node... and set the idom of NewBB. 277 DomTreeNodeBase<NodeT> *NewBBNode = DT.addNewBlock(NewBB, NewBBIDom); 278 279 // If NewBB strictly dominates other blocks, then it is now the immediate 280 // dominator of NewBBSucc. Update the dominator tree as appropriate. 281 if (NewBBDominatesNewBBSucc) { 282 DomTreeNodeBase<NodeT> *NewBBSuccNode = DT.getNode(NewBBSucc); 283 DT.changeImmediateDominator(NewBBSuccNode, NewBBNode); 284 } 285 } 286 287public: 288 explicit DominatorTreeBase(bool isPostDom) 289 : DominatorBase<NodeT>(isPostDom), DFSInfoValid(false), SlowQueries(0) {} 290 virtual ~DominatorTreeBase() { reset(); } 291 292 /// compare - Return false if the other dominator tree base matches this 293 /// dominator tree base. Otherwise return true. 294 bool compare(DominatorTreeBase &Other) const { 295 296 const DomTreeNodeMapType &OtherDomTreeNodes = Other.DomTreeNodes; 297 if (DomTreeNodes.size() != OtherDomTreeNodes.size()) 298 return true; 299 300 for (typename DomTreeNodeMapType::const_iterator 301 I = this->DomTreeNodes.begin(), 302 E = this->DomTreeNodes.end(); I != E; ++I) { 303 NodeT *BB = I->first; 304 typename DomTreeNodeMapType::const_iterator OI = OtherDomTreeNodes.find(BB); 305 if (OI == OtherDomTreeNodes.end()) 306 return true; 307 308 DomTreeNodeBase<NodeT>* MyNd = I->second; 309 DomTreeNodeBase<NodeT>* OtherNd = OI->second; 310 311 if (MyNd->compare(OtherNd)) 312 return true; 313 } 314 315 return false; 316 } 317 318 virtual void releaseMemory() { reset(); } 319 320 /// getNode - return the (Post)DominatorTree node for the specified basic 321 /// block. This is the same as using operator[] on this class. 322 /// 323 inline DomTreeNodeBase<NodeT> *getNode(NodeT *BB) const { 324 return DomTreeNodes.lookup(BB); 325 } 326 327 /// getRootNode - This returns the entry node for the CFG of the function. If 328 /// this tree represents the post-dominance relations for a function, however, 329 /// this root may be a node with the block == NULL. This is the case when 330 /// there are multiple exit nodes from a particular function. Consumers of 331 /// post-dominance information must be capable of dealing with this 332 /// possibility. 333 /// 334 DomTreeNodeBase<NodeT> *getRootNode() { return RootNode; } 335 const DomTreeNodeBase<NodeT> *getRootNode() const { return RootNode; } 336 337 /// properlyDominates - Returns true iff this dominates N and this != N. 338 /// Note that this is not a constant time operation! 339 /// 340 bool properlyDominates(const DomTreeNodeBase<NodeT> *A, 341 const DomTreeNodeBase<NodeT> *B) const { 342 if (A == 0 || B == 0) return false; 343 return dominatedBySlowTreeWalk(A, B); 344 } 345 346 inline bool properlyDominates(const NodeT *A, const NodeT *B) { 347 if (A == B) 348 return false; 349 350 // Cast away the const qualifiers here. This is ok since 351 // this function doesn't actually return the values returned 352 // from getNode. 353 return properlyDominates(getNode(const_cast<NodeT *>(A)), 354 getNode(const_cast<NodeT *>(B))); 355 } 356 357 bool dominatedBySlowTreeWalk(const DomTreeNodeBase<NodeT> *A, 358 const DomTreeNodeBase<NodeT> *B) const { 359 const DomTreeNodeBase<NodeT> *IDom; 360 if (A == 0 || B == 0) return false; 361 while ((IDom = B->getIDom()) != 0 && IDom != A && IDom != B) 362 B = IDom; // Walk up the tree 363 return IDom != 0; 364 } 365 366 367 /// isReachableFromEntry - Return true if A is dominated by the entry 368 /// block of the function containing it. 369 bool isReachableFromEntry(const NodeT* A) { 370 assert(!this->isPostDominator() && 371 "This is not implemented for post dominators"); 372 return dominates(&A->getParent()->front(), 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 if (B == A) 381 return true; // A node trivially dominates itself. 382 383 if (A == 0 || B == 0) 384 return false; 385 386 // Compare the result of the tree walk and the dfs numbers, if expensive 387 // checks are enabled. 388#ifdef XDEBUG 389 assert((!DFSInfoValid || 390 (dominatedBySlowTreeWalk(A, B) == B->DominatedBy(A))) && 391 "Tree walk disagrees with dfs numbers!"); 392#endif 393 394 if (DFSInfoValid) 395 return B->DominatedBy(A); 396 397 // If we end up with too many slow queries, just update the 398 // DFS numbers on the theory that we are going to keep querying. 399 SlowQueries++; 400 if (SlowQueries > 32) { 401 updateDFSNumbers(); 402 return B->DominatedBy(A); 403 } 404 405 return dominatedBySlowTreeWalk(A, B); 406 } 407 408 inline bool dominates(const NodeT *A, const NodeT *B) { 409 if (A == B) 410 return true; 411 412 // Cast away the const qualifiers here. This is ok since 413 // this function doesn't actually return the values returned 414 // from getNode. 415 return dominates(getNode(const_cast<NodeT *>(A)), 416 getNode(const_cast<NodeT *>(B))); 417 } 418 419 NodeT *getRoot() const { 420 assert(this->Roots.size() == 1 && "Should always have entry node!"); 421 return this->Roots[0]; 422 } 423 424 /// findNearestCommonDominator - Find nearest common dominator basic block 425 /// for basic block A and B. If there is no such block then return NULL. 426 NodeT *findNearestCommonDominator(NodeT *A, NodeT *B) { 427 assert(A->getParent() == B->getParent() && 428 "Two blocks are not in same function"); 429 430 // If either A or B is a entry block then it is nearest common dominator 431 // (for forward-dominators). 432 if (!this->isPostDominator()) { 433 NodeT &Entry = A->getParent()->front(); 434 if (A == &Entry || B == &Entry) 435 return &Entry; 436 } 437 438 // If B dominates A then B is nearest common dominator. 439 if (dominates(B, A)) 440 return B; 441 442 // If A dominates B then A is nearest common dominator. 443 if (dominates(A, B)) 444 return A; 445 446 DomTreeNodeBase<NodeT> *NodeA = getNode(A); 447 DomTreeNodeBase<NodeT> *NodeB = getNode(B); 448 449 // Collect NodeA dominators set. 450 SmallPtrSet<DomTreeNodeBase<NodeT>*, 16> NodeADoms; 451 NodeADoms.insert(NodeA); 452 DomTreeNodeBase<NodeT> *IDomA = NodeA->getIDom(); 453 while (IDomA) { 454 NodeADoms.insert(IDomA); 455 IDomA = IDomA->getIDom(); 456 } 457 458 // Walk NodeB immediate dominators chain and find common dominator node. 459 DomTreeNodeBase<NodeT> *IDomB = NodeB->getIDom(); 460 while (IDomB) { 461 if (NodeADoms.count(IDomB) != 0) 462 return IDomB->getBlock(); 463 464 IDomB = IDomB->getIDom(); 465 } 466 467 return NULL; 468 } 469 470 const NodeT *findNearestCommonDominator(const NodeT *A, const NodeT *B) { 471 // Cast away the const qualifiers here. This is ok since 472 // const is re-introduced on the return type. 473 return findNearestCommonDominator(const_cast<NodeT *>(A), 474 const_cast<NodeT *>(B)); 475 } 476 477 //===--------------------------------------------------------------------===// 478 // API to update (Post)DominatorTree information based on modifications to 479 // the CFG... 480 481 /// addNewBlock - Add a new node to the dominator tree information. This 482 /// creates a new node as a child of DomBB dominator node,linking it into 483 /// the children list of the immediate dominator. 484 DomTreeNodeBase<NodeT> *addNewBlock(NodeT *BB, NodeT *DomBB) { 485 assert(getNode(BB) == 0 && "Block already in dominator tree!"); 486 DomTreeNodeBase<NodeT> *IDomNode = getNode(DomBB); 487 assert(IDomNode && "Not immediate dominator specified for block!"); 488 DFSInfoValid = false; 489 return DomTreeNodes[BB] = 490 IDomNode->addChild(new DomTreeNodeBase<NodeT>(BB, IDomNode)); 491 } 492 493 /// changeImmediateDominator - This method is used to update the dominator 494 /// tree information when a node's immediate dominator changes. 495 /// 496 void changeImmediateDominator(DomTreeNodeBase<NodeT> *N, 497 DomTreeNodeBase<NodeT> *NewIDom) { 498 assert(N && NewIDom && "Cannot change null node pointers!"); 499 DFSInfoValid = false; 500 N->setIDom(NewIDom); 501 } 502 503 void changeImmediateDominator(NodeT *BB, NodeT *NewBB) { 504 changeImmediateDominator(getNode(BB), getNode(NewBB)); 505 } 506 507 /// eraseNode - Removes a node from the dominator tree. Block must not 508 /// dominate any other blocks. Removes node from its immediate dominator's 509 /// children list. Deletes dominator node associated with basic block BB. 510 void eraseNode(NodeT *BB) { 511 DomTreeNodeBase<NodeT> *Node = getNode(BB); 512 assert(Node && "Removing node that isn't in dominator tree."); 513 assert(Node->getChildren().empty() && "Node is not a leaf node."); 514 515 // Remove node from immediate dominator's children list. 516 DomTreeNodeBase<NodeT> *IDom = Node->getIDom(); 517 if (IDom) { 518 typename std::vector<DomTreeNodeBase<NodeT>*>::iterator I = 519 std::find(IDom->Children.begin(), IDom->Children.end(), Node); 520 assert(I != IDom->Children.end() && 521 "Not in immediate dominator children set!"); 522 // I am no longer your child... 523 IDom->Children.erase(I); 524 } 525 526 DomTreeNodes.erase(BB); 527 delete Node; 528 } 529 530 /// removeNode - Removes a node from the dominator tree. Block must not 531 /// dominate any other blocks. Invalidates any node pointing to removed 532 /// block. 533 void removeNode(NodeT *BB) { 534 assert(getNode(BB) && "Removing node that isn't in dominator tree."); 535 DomTreeNodes.erase(BB); 536 } 537 538 /// splitBlock - BB is split and now it has one successor. Update dominator 539 /// tree to reflect this change. 540 void splitBlock(NodeT* NewBB) { 541 if (this->IsPostDominators) 542 this->Split<Inverse<NodeT*>, GraphTraits<Inverse<NodeT*> > >(*this, NewBB); 543 else 544 this->Split<NodeT*, GraphTraits<NodeT*> >(*this, NewBB); 545 } 546 547 /// print - Convert to human readable form 548 /// 549 void print(raw_ostream &o) const { 550 o << "=============================--------------------------------\n"; 551 if (this->isPostDominator()) 552 o << "Inorder PostDominator Tree: "; 553 else 554 o << "Inorder Dominator Tree: "; 555 if (!this->DFSInfoValid) 556 o << "DFSNumbers invalid: " << SlowQueries << " slow queries."; 557 o << "\n"; 558 559 // The postdom tree can have a null root if there are no returns. 560 if (getRootNode()) 561 PrintDomTree<NodeT>(getRootNode(), o, 1); 562 } 563 564protected: 565 template<class GraphT> 566 friend typename GraphT::NodeType* Eval( 567 DominatorTreeBase<typename GraphT::NodeType>& DT, 568 typename GraphT::NodeType* V, 569 unsigned LastLinked); 570 571 template<class GraphT> 572 friend unsigned DFSPass(DominatorTreeBase<typename GraphT::NodeType>& DT, 573 typename GraphT::NodeType* V, 574 unsigned N); 575 576 template<class FuncT, class N> 577 friend void Calculate(DominatorTreeBase<typename GraphTraits<N>::NodeType>& DT, 578 FuncT& F); 579 580 /// updateDFSNumbers - Assign In and Out numbers to the nodes while walking 581 /// dominator tree in dfs order. 582 void updateDFSNumbers() { 583 unsigned DFSNum = 0; 584 585 SmallVector<std::pair<DomTreeNodeBase<NodeT>*, 586 typename DomTreeNodeBase<NodeT>::iterator>, 32> WorkStack; 587 588 DomTreeNodeBase<NodeT> *ThisRoot = getRootNode(); 589 590 if (!ThisRoot) 591 return; 592 593 // Even in the case of multiple exits that form the post dominator root 594 // nodes, do not iterate over all exits, but start from the virtual root 595 // node. Otherwise bbs, that are not post dominated by any exit but by the 596 // virtual root node, will never be assigned a DFS number. 597 WorkStack.push_back(std::make_pair(ThisRoot, ThisRoot->begin())); 598 ThisRoot->DFSNumIn = DFSNum++; 599 600 while (!WorkStack.empty()) { 601 DomTreeNodeBase<NodeT> *Node = WorkStack.back().first; 602 typename DomTreeNodeBase<NodeT>::iterator ChildIt = 603 WorkStack.back().second; 604 605 // If we visited all of the children of this node, "recurse" back up the 606 // stack setting the DFOutNum. 607 if (ChildIt == Node->end()) { 608 Node->DFSNumOut = DFSNum++; 609 WorkStack.pop_back(); 610 } else { 611 // Otherwise, recursively visit this child. 612 DomTreeNodeBase<NodeT> *Child = *ChildIt; 613 ++WorkStack.back().second; 614 615 WorkStack.push_back(std::make_pair(Child, Child->begin())); 616 Child->DFSNumIn = DFSNum++; 617 } 618 } 619 620 SlowQueries = 0; 621 DFSInfoValid = true; 622 } 623 624 DomTreeNodeBase<NodeT> *getNodeForBlock(NodeT *BB) { 625 if (DomTreeNodeBase<NodeT> *Node = getNode(BB)) 626 return Node; 627 628 // Haven't calculated this node yet? Get or calculate the node for the 629 // immediate dominator. 630 NodeT *IDom = getIDom(BB); 631 632 assert(IDom || this->DomTreeNodes[NULL]); 633 DomTreeNodeBase<NodeT> *IDomNode = getNodeForBlock(IDom); 634 635 // Add a new tree node for this BasicBlock, and link it as a child of 636 // IDomNode 637 DomTreeNodeBase<NodeT> *C = new DomTreeNodeBase<NodeT>(BB, IDomNode); 638 return this->DomTreeNodes[BB] = IDomNode->addChild(C); 639 } 640 641 inline NodeT *getIDom(NodeT *BB) const { 642 return IDoms.lookup(BB); 643 } 644 645 inline void addRoot(NodeT* BB) { 646 this->Roots.push_back(BB); 647 } 648 649public: 650 /// recalculate - compute a dominator tree for the given function 651 template<class FT> 652 void recalculate(FT& F) { 653 typedef GraphTraits<FT*> TraitsTy; 654 reset(); 655 this->Vertex.push_back(0); 656 657 if (!this->IsPostDominators) { 658 // Initialize root 659 NodeT *entry = TraitsTy::getEntryNode(&F); 660 this->Roots.push_back(entry); 661 this->IDoms[entry] = 0; 662 this->DomTreeNodes[entry] = 0; 663 664 Calculate<FT, NodeT*>(*this, F); 665 } else { 666 // Initialize the roots list 667 for (typename TraitsTy::nodes_iterator I = TraitsTy::nodes_begin(&F), 668 E = TraitsTy::nodes_end(&F); I != E; ++I) { 669 if (std::distance(TraitsTy::child_begin(I), 670 TraitsTy::child_end(I)) == 0) 671 addRoot(I); 672 673 // Prepopulate maps so that we don't get iterator invalidation issues later. 674 this->IDoms[I] = 0; 675 this->DomTreeNodes[I] = 0; 676 } 677 678 Calculate<FT, Inverse<NodeT*> >(*this, F); 679 } 680 } 681}; 682 683EXTERN_TEMPLATE_INSTANTIATION(class DominatorTreeBase<BasicBlock>); 684 685//===------------------------------------- 686/// DominatorTree Class - Concrete subclass of DominatorTreeBase that is used to 687/// compute a normal dominator tree. 688/// 689class DominatorTree : public FunctionPass { 690public: 691 static char ID; // Pass ID, replacement for typeid 692 DominatorTreeBase<BasicBlock>* DT; 693 694 DominatorTree() : FunctionPass(ID) { 695 initializeDominatorTreePass(*PassRegistry::getPassRegistry()); 696 DT = new DominatorTreeBase<BasicBlock>(false); 697 } 698 699 ~DominatorTree() { 700 delete DT; 701 } 702 703 DominatorTreeBase<BasicBlock>& getBase() { return *DT; } 704 705 /// getRoots - Return the root blocks of the current CFG. This may include 706 /// multiple blocks if we are computing post dominators. For forward 707 /// dominators, this will always be a single block (the entry node). 708 /// 709 inline const std::vector<BasicBlock*> &getRoots() const { 710 return DT->getRoots(); 711 } 712 713 inline BasicBlock *getRoot() const { 714 return DT->getRoot(); 715 } 716 717 inline DomTreeNode *getRootNode() const { 718 return DT->getRootNode(); 719 } 720 721 /// compare - Return false if the other dominator tree matches this 722 /// dominator tree. Otherwise return true. 723 inline bool compare(DominatorTree &Other) const { 724 DomTreeNode *R = getRootNode(); 725 DomTreeNode *OtherR = Other.getRootNode(); 726 727 if (!R || !OtherR || R->getBlock() != OtherR->getBlock()) 728 return true; 729 730 if (DT->compare(Other.getBase())) 731 return true; 732 733 return false; 734 } 735 736 virtual bool runOnFunction(Function &F); 737 738 virtual void verifyAnalysis() const; 739 740 virtual void getAnalysisUsage(AnalysisUsage &AU) const { 741 AU.setPreservesAll(); 742 } 743 744 inline bool dominates(const DomTreeNode* A, const DomTreeNode* B) const { 745 return DT->dominates(A, B); 746 } 747 748 inline bool dominates(const BasicBlock* A, const BasicBlock* B) const { 749 return DT->dominates(A, B); 750 } 751 752 // dominates - Return true if A dominates B. This performs the 753 // special checks necessary if A and B are in the same basic block. 754 bool dominates(const Instruction *A, const Instruction *B) const; 755 756 /// properlyDominates - Use this instead of dominates() to determine whether a 757 /// user of A can be hoisted above B. 758 bool properlyDominates(const Instruction *A, const Instruction *B) const { 759 return A != B && dominates(A, B); 760 } 761 762 bool properlyDominates(const DomTreeNode *A, const DomTreeNode *B) const { 763 return DT->properlyDominates(A, B); 764 } 765 766 bool properlyDominates(const BasicBlock *A, const BasicBlock *B) const { 767 return DT->properlyDominates(A, B); 768 } 769 770 /// findNearestCommonDominator - Find nearest common dominator basic block 771 /// for basic block A and B. If there is no such block then return NULL. 772 inline BasicBlock *findNearestCommonDominator(BasicBlock *A, BasicBlock *B) { 773 return DT->findNearestCommonDominator(A, B); 774 } 775 776 inline const BasicBlock *findNearestCommonDominator(const BasicBlock *A, 777 const BasicBlock *B) { 778 return DT->findNearestCommonDominator(A, B); 779 } 780 781 inline DomTreeNode *operator[](BasicBlock *BB) const { 782 return DT->getNode(BB); 783 } 784 785 /// getNode - return the (Post)DominatorTree node for the specified basic 786 /// block. This is the same as using operator[] on this class. 787 /// 788 inline DomTreeNode *getNode(BasicBlock *BB) const { 789 return DT->getNode(BB); 790 } 791 792 /// addNewBlock - Add a new node to the dominator tree information. This 793 /// creates a new node as a child of DomBB dominator node,linking it into 794 /// the children list of the immediate dominator. 795 inline DomTreeNode *addNewBlock(BasicBlock *BB, BasicBlock *DomBB) { 796 return DT->addNewBlock(BB, DomBB); 797 } 798 799 /// changeImmediateDominator - This method is used to update the dominator 800 /// tree information when a node's immediate dominator changes. 801 /// 802 inline void changeImmediateDominator(BasicBlock *N, BasicBlock* NewIDom) { 803 DT->changeImmediateDominator(N, NewIDom); 804 } 805 806 inline void changeImmediateDominator(DomTreeNode *N, DomTreeNode* NewIDom) { 807 DT->changeImmediateDominator(N, NewIDom); 808 } 809 810 /// eraseNode - Removes a node from the dominator tree. Block must not 811 /// dominate any other blocks. Removes node from its immediate dominator's 812 /// children list. Deletes dominator node associated with basic block BB. 813 inline void eraseNode(BasicBlock *BB) { 814 DT->eraseNode(BB); 815 } 816 817 /// splitBlock - BB is split and now it has one successor. Update dominator 818 /// tree to reflect this change. 819 inline void splitBlock(BasicBlock* NewBB) { 820 DT->splitBlock(NewBB); 821 } 822 823 bool isReachableFromEntry(const BasicBlock* A) { 824 return DT->isReachableFromEntry(A); 825 } 826 827 828 virtual void releaseMemory() { 829 DT->releaseMemory(); 830 } 831 832 virtual void print(raw_ostream &OS, const Module* M= 0) const; 833}; 834 835//===------------------------------------- 836/// DominatorTree GraphTraits specialization so the DominatorTree can be 837/// iterable by generic graph iterators. 838/// 839template <> struct GraphTraits<DomTreeNode*> { 840 typedef DomTreeNode NodeType; 841 typedef NodeType::iterator ChildIteratorType; 842 843 static NodeType *getEntryNode(NodeType *N) { 844 return N; 845 } 846 static inline ChildIteratorType child_begin(NodeType *N) { 847 return N->begin(); 848 } 849 static inline ChildIteratorType child_end(NodeType *N) { 850 return N->end(); 851 } 852 853 typedef df_iterator<DomTreeNode*> nodes_iterator; 854 855 static nodes_iterator nodes_begin(DomTreeNode *N) { 856 return df_begin(getEntryNode(N)); 857 } 858 859 static nodes_iterator nodes_end(DomTreeNode *N) { 860 return df_end(getEntryNode(N)); 861 } 862}; 863 864template <> struct GraphTraits<DominatorTree*> 865 : public GraphTraits<DomTreeNode*> { 866 static NodeType *getEntryNode(DominatorTree *DT) { 867 return DT->getRootNode(); 868 } 869 870 static nodes_iterator nodes_begin(DominatorTree *N) { 871 return df_begin(getEntryNode(N)); 872 } 873 874 static nodes_iterator nodes_end(DominatorTree *N) { 875 return df_end(getEntryNode(N)); 876 } 877}; 878 879 880} // End llvm namespace 881 882#endif 883