Dominators.h revision 3445d9a72aec68512df265705e2be7704496f541
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 following classes: 11// 1. DominatorTree: Represent dominators as an explicit tree structure. 12// 2. DominanceFrontier: Calculate and hold the dominance frontier for a 13// function. 14// 15// These data structures are listed in increasing order of complexity. It 16// takes longer to calculate the dominator frontier, for example, than the 17// DominatorTree mapping. 18// 19//===----------------------------------------------------------------------===// 20 21#ifndef LLVM_ANALYSIS_DOMINATORS_H 22#define LLVM_ANALYSIS_DOMINATORS_H 23 24#include "llvm/Pass.h" 25#include "llvm/Function.h" 26#include "llvm/Instructions.h" 27#include "llvm/ADT/DenseMap.h" 28#include "llvm/ADT/GraphTraits.h" 29#include "llvm/ADT/SmallPtrSet.h" 30#include "llvm/ADT/SmallVector.h" 31#include "llvm/Assembly/Writer.h" 32#include "llvm/Support/CFG.h" 33#include "llvm/Support/Compiler.h" 34#include "llvm/Support/raw_ostream.h" 35#include <algorithm> 36#include <map> 37#include <set> 38 39namespace llvm { 40 41//===----------------------------------------------------------------------===// 42/// DominatorBase - Base class that other, more interesting dominator analyses 43/// inherit from. 44/// 45template <class NodeT> 46class DominatorBase { 47protected: 48 std::vector<NodeT*> Roots; 49 const bool IsPostDominators; 50 inline explicit DominatorBase(bool isPostDom) : 51 Roots(), IsPostDominators(isPostDom) {} 52public: 53 54 /// getRoots - Return the root blocks of the current CFG. This may include 55 /// multiple blocks if we are computing post dominators. For forward 56 /// dominators, this will always be a single block (the entry node). 57 /// 58 inline const std::vector<NodeT*> &getRoots() const { return Roots; } 59 60 /// isPostDominator - Returns true if analysis based of postdoms 61 /// 62 bool isPostDominator() const { return IsPostDominators; } 63}; 64 65 66//===----------------------------------------------------------------------===// 67// DomTreeNode - Dominator Tree Node 68template<class NodeT> class DominatorTreeBase; 69struct PostDominatorTree; 70class MachineBasicBlock; 71 72template <class NodeT> 73class DomTreeNodeBase { 74 NodeT *TheBB; 75 DomTreeNodeBase<NodeT> *IDom; 76 std::vector<DomTreeNodeBase<NodeT> *> Children; 77 int DFSNumIn, DFSNumOut; 78 79 template<class N> friend class DominatorTreeBase; 80 friend struct PostDominatorTree; 81public: 82 typedef typename std::vector<DomTreeNodeBase<NodeT> *>::iterator iterator; 83 typedef typename std::vector<DomTreeNodeBase<NodeT> *>::const_iterator 84 const_iterator; 85 86 iterator begin() { return Children.begin(); } 87 iterator end() { return Children.end(); } 88 const_iterator begin() const { return Children.begin(); } 89 const_iterator end() const { return Children.end(); } 90 91 NodeT *getBlock() const { return TheBB; } 92 DomTreeNodeBase<NodeT> *getIDom() const { return IDom; } 93 const std::vector<DomTreeNodeBase<NodeT>*> &getChildren() const { 94 return Children; 95 } 96 97 DomTreeNodeBase(NodeT *BB, DomTreeNodeBase<NodeT> *iDom) 98 : TheBB(BB), IDom(iDom), DFSNumIn(-1), DFSNumOut(-1) { } 99 100 DomTreeNodeBase<NodeT> *addChild(DomTreeNodeBase<NodeT> *C) { 101 Children.push_back(C); 102 return C; 103 } 104 105 size_t getNumChildren() const { 106 return Children.size(); 107 } 108 109 void clearAllChildren() { 110 Children.clear(); 111 } 112 113 bool compare(DomTreeNodeBase<NodeT> *Other) { 114 if (getNumChildren() != Other->getNumChildren()) 115 return true; 116 117 SmallPtrSet<NodeT *, 4> OtherChildren; 118 for(iterator I = Other->begin(), E = Other->end(); I != E; ++I) { 119 NodeT *Nd = (*I)->getBlock(); 120 OtherChildren.insert(Nd); 121 } 122 123 for(iterator I = begin(), E = end(); I != E; ++I) { 124 NodeT *N = (*I)->getBlock(); 125 if (OtherChildren.count(N) == 0) 126 return true; 127 } 128 return false; 129 } 130 131 void setIDom(DomTreeNodeBase<NodeT> *NewIDom) { 132 assert(IDom && "No immediate dominator?"); 133 if (IDom != NewIDom) { 134 typename std::vector<DomTreeNodeBase<NodeT>*>::iterator I = 135 std::find(IDom->Children.begin(), IDom->Children.end(), this); 136 assert(I != IDom->Children.end() && 137 "Not in immediate dominator children set!"); 138 // I am no longer your child... 139 IDom->Children.erase(I); 140 141 // Switch to new dominator 142 IDom = NewIDom; 143 IDom->Children.push_back(this); 144 } 145 } 146 147 /// getDFSNumIn/getDFSNumOut - These are an internal implementation detail, do 148 /// not call them. 149 unsigned getDFSNumIn() const { return DFSNumIn; } 150 unsigned getDFSNumOut() const { return DFSNumOut; } 151private: 152 // Return true if this node is dominated by other. Use this only if DFS info 153 // is valid. 154 bool DominatedBy(const DomTreeNodeBase<NodeT> *other) const { 155 return this->DFSNumIn >= other->DFSNumIn && 156 this->DFSNumOut <= other->DFSNumOut; 157 } 158}; 159 160EXTERN_TEMPLATE_INSTANTIATION(class DomTreeNodeBase<BasicBlock>); 161EXTERN_TEMPLATE_INSTANTIATION(class DomTreeNodeBase<MachineBasicBlock>); 162 163template<class NodeT> 164static raw_ostream &operator<<(raw_ostream &o, 165 const DomTreeNodeBase<NodeT> *Node) { 166 if (Node->getBlock()) 167 WriteAsOperand(o, Node->getBlock(), false); 168 else 169 o << " <<exit node>>"; 170 171 o << " {" << Node->getDFSNumIn() << "," << Node->getDFSNumOut() << "}"; 172 173 return o << "\n"; 174} 175 176template<class NodeT> 177static void PrintDomTree(const DomTreeNodeBase<NodeT> *N, raw_ostream &o, 178 unsigned Lev) { 179 o.indent(2*Lev) << "[" << Lev << "] " << N; 180 for (typename DomTreeNodeBase<NodeT>::const_iterator I = N->begin(), 181 E = N->end(); I != E; ++I) 182 PrintDomTree<NodeT>(*I, o, Lev+1); 183} 184 185typedef DomTreeNodeBase<BasicBlock> DomTreeNode; 186 187//===----------------------------------------------------------------------===// 188/// DominatorTree - Calculate the immediate dominator tree for a function. 189/// 190 191template<class FuncT, class N> 192void Calculate(DominatorTreeBase<typename GraphTraits<N>::NodeType>& DT, 193 FuncT& F); 194 195template<class NodeT> 196class DominatorTreeBase : public DominatorBase<NodeT> { 197protected: 198 typedef DenseMap<NodeT*, DomTreeNodeBase<NodeT>*> DomTreeNodeMapType; 199 DomTreeNodeMapType DomTreeNodes; 200 DomTreeNodeBase<NodeT> *RootNode; 201 202 bool DFSInfoValid; 203 unsigned int SlowQueries; 204 // Information record used during immediate dominators computation. 205 struct InfoRec { 206 unsigned DFSNum; 207 unsigned Semi; 208 unsigned Size; 209 NodeT *Label, *Child; 210 unsigned Parent, Ancestor; 211 212 std::vector<NodeT*> Bucket; 213 214 InfoRec() : DFSNum(0), Semi(0), Size(0), Label(0), Child(0), Parent(0), 215 Ancestor(0) {} 216 }; 217 218 DenseMap<NodeT*, NodeT*> IDoms; 219 220 // Vertex - Map the DFS number to the BasicBlock* 221 std::vector<NodeT*> Vertex; 222 223 // Info - Collection of information used during the computation of idoms. 224 DenseMap<NodeT*, InfoRec> Info; 225 226 void reset() { 227 for (typename DomTreeNodeMapType::iterator I = this->DomTreeNodes.begin(), 228 E = DomTreeNodes.end(); I != E; ++I) 229 delete I->second; 230 DomTreeNodes.clear(); 231 IDoms.clear(); 232 this->Roots.clear(); 233 Vertex.clear(); 234 RootNode = 0; 235 } 236 237 // NewBB is split and now it has one successor. Update dominator tree to 238 // reflect this change. 239 template<class N, class GraphT> 240 void Split(DominatorTreeBase<typename GraphT::NodeType>& DT, 241 typename GraphT::NodeType* NewBB) { 242 assert(std::distance(GraphT::child_begin(NewBB), 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 for (typename GraphTraits<Inverse<N> >::ChildIteratorType PI = 248 GraphTraits<Inverse<N> >::child_begin(NewBB), 249 PE = GraphTraits<Inverse<N> >::child_end(NewBB); PI != PE; ++PI) 250 PredBlocks.push_back(*PI); 251 252 assert(!PredBlocks.empty() && "No predblocks??"); 253 254 bool NewBBDominatesNewBBSucc = true; 255 for (typename GraphTraits<Inverse<N> >::ChildIteratorType PI = 256 GraphTraits<Inverse<N> >::child_begin(NewBBSucc), 257 E = GraphTraits<Inverse<N> >::child_end(NewBBSucc); PI != E; ++PI) 258 if (*PI != NewBB && !DT.dominates(NewBBSucc, *PI) && 259 DT.isReachableFromEntry(*PI)) { 260 NewBBDominatesNewBBSucc = false; 261 break; 262 } 263 264 // Find NewBB's immediate dominator and create new dominator tree node for 265 // NewBB. 266 NodeT *NewBBIDom = 0; 267 unsigned i = 0; 268 for (i = 0; i < PredBlocks.size(); ++i) 269 if (DT.isReachableFromEntry(PredBlocks[i])) { 270 NewBBIDom = PredBlocks[i]; 271 break; 272 } 273 274 // It's possible that none of the predecessors of NewBB are reachable; 275 // in that case, NewBB itself is unreachable, so nothing needs to be 276 // changed. 277 if (!NewBBIDom) 278 return; 279 280 for (i = i + 1; i < PredBlocks.size(); ++i) { 281 if (DT.isReachableFromEntry(PredBlocks[i])) 282 NewBBIDom = DT.findNearestCommonDominator(NewBBIDom, PredBlocks[i]); 283 } 284 285 // Create the new dominator tree node... and set the idom of NewBB. 286 DomTreeNodeBase<NodeT> *NewBBNode = DT.addNewBlock(NewBB, NewBBIDom); 287 288 // If NewBB strictly dominates other blocks, then it is now the immediate 289 // dominator of NewBBSucc. Update the dominator tree as appropriate. 290 if (NewBBDominatesNewBBSucc) { 291 DomTreeNodeBase<NodeT> *NewBBSuccNode = DT.getNode(NewBBSucc); 292 DT.changeImmediateDominator(NewBBSuccNode, NewBBNode); 293 } 294 } 295 296public: 297 explicit DominatorTreeBase(bool isPostDom) 298 : DominatorBase<NodeT>(isPostDom), DFSInfoValid(false), SlowQueries(0) {} 299 virtual ~DominatorTreeBase() { reset(); } 300 301 // FIXME: Should remove this 302 virtual bool runOnFunction(Function &F) { return false; } 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 SmallPtrSet<const NodeT *,4> MyBBs; 313 for (typename DomTreeNodeMapType::const_iterator 314 I = this->DomTreeNodes.begin(), 315 E = this->DomTreeNodes.end(); I != E; ++I) { 316 NodeT *BB = I->first; 317 typename DomTreeNodeMapType::const_iterator OI = OtherDomTreeNodes.find(BB); 318 if (OI == OtherDomTreeNodes.end()) 319 return true; 320 321 DomTreeNodeBase<NodeT>* MyNd = I->second; 322 DomTreeNodeBase<NodeT>* OtherNd = OI->second; 323 324 if (MyNd->compare(OtherNd)) 325 return true; 326 } 327 328 return false; 329 } 330 331 virtual void releaseMemory() { reset(); } 332 333 /// getNode - return the (Post)DominatorTree node for the specified basic 334 /// block. This is the same as using operator[] on this class. 335 /// 336 inline DomTreeNodeBase<NodeT> *getNode(NodeT *BB) const { 337 typename DomTreeNodeMapType::const_iterator I = DomTreeNodes.find(BB); 338 return I != DomTreeNodes.end() ? I->second : 0; 339 } 340 341 /// getRootNode - This returns the entry node for the CFG of the function. If 342 /// this tree represents the post-dominance relations for a function, however, 343 /// this root may be a node with the block == NULL. This is the case when 344 /// there are multiple exit nodes from a particular function. Consumers of 345 /// post-dominance information must be capable of dealing with this 346 /// possibility. 347 /// 348 DomTreeNodeBase<NodeT> *getRootNode() { return RootNode; } 349 const DomTreeNodeBase<NodeT> *getRootNode() const { return RootNode; } 350 351 /// properlyDominates - Returns true iff this dominates N and this != N. 352 /// Note that this is not a constant time operation! 353 /// 354 bool properlyDominates(const DomTreeNodeBase<NodeT> *A, 355 const DomTreeNodeBase<NodeT> *B) const { 356 if (A == 0 || B == 0) return false; 357 return dominatedBySlowTreeWalk(A, B); 358 } 359 360 inline bool properlyDominates(NodeT *A, NodeT *B) { 361 return properlyDominates(getNode(A), getNode(B)); 362 } 363 364 bool dominatedBySlowTreeWalk(const DomTreeNodeBase<NodeT> *A, 365 const DomTreeNodeBase<NodeT> *B) const { 366 const DomTreeNodeBase<NodeT> *IDom; 367 if (A == 0 || B == 0) return false; 368 while ((IDom = B->getIDom()) != 0 && IDom != A && IDom != B) 369 B = IDom; // Walk up the tree 370 return IDom != 0; 371 } 372 373 374 /// isReachableFromEntry - Return true if A is dominated by the entry 375 /// block of the function containing it. 376 bool isReachableFromEntry(NodeT* A) { 377 assert (!this->isPostDominator() 378 && "This is not implemented for post dominators"); 379 return dominates(&A->getParent()->front(), A); 380 } 381 382 /// dominates - Returns true iff A dominates B. Note that this is not a 383 /// constant time operation! 384 /// 385 inline bool dominates(const DomTreeNodeBase<NodeT> *A, 386 const DomTreeNodeBase<NodeT> *B) { 387 if (B == A) 388 return true; // A node trivially dominates itself. 389 390 if (A == 0 || B == 0) 391 return false; 392 393 if (DFSInfoValid) 394 return B->DominatedBy(A); 395 396 // If we end up with too many slow queries, just update the 397 // DFS numbers on the theory that we are going to keep querying. 398 SlowQueries++; 399 if (SlowQueries > 32) { 400 updateDFSNumbers(); 401 return B->DominatedBy(A); 402 } 403 404 return dominatedBySlowTreeWalk(A, B); 405 } 406 407 inline bool dominates(const NodeT *A, const NodeT *B) { 408 if (A == B) 409 return true; 410 411 // Cast away the const qualifiers here. This is ok since 412 // this function doesn't actually return the values returned 413 // from getNode. 414 return dominates(getNode(const_cast<NodeT *>(A)), 415 getNode(const_cast<NodeT *>(B))); 416 } 417 418 NodeT *getRoot() const { 419 assert(this->Roots.size() == 1 && "Should always have entry node!"); 420 return this->Roots[0]; 421 } 422 423 /// findNearestCommonDominator - Find nearest common dominator basic block 424 /// for basic block A and B. If there is no such block then return NULL. 425 NodeT *findNearestCommonDominator(NodeT *A, NodeT *B) { 426 427 assert (!this->isPostDominator() 428 && "This is not implemented for post dominators"); 429 assert (A->getParent() == B->getParent() 430 && "Two blocks are not in same function"); 431 432 // If either A or B is a entry block then it is nearest common dominator. 433 NodeT &Entry = A->getParent()->front(); 434 if (A == &Entry || B == &Entry) 435 return &Entry; 436 437 // If B dominates A then B is nearest common dominator. 438 if (dominates(B, A)) 439 return B; 440 441 // If A dominates B then A is nearest common dominator. 442 if (dominates(A, B)) 443 return A; 444 445 DomTreeNodeBase<NodeT> *NodeA = getNode(A); 446 DomTreeNodeBase<NodeT> *NodeB = getNode(B); 447 448 // Collect NodeA dominators set. 449 SmallPtrSet<DomTreeNodeBase<NodeT>*, 16> NodeADoms; 450 NodeADoms.insert(NodeA); 451 DomTreeNodeBase<NodeT> *IDomA = NodeA->getIDom(); 452 while (IDomA) { 453 NodeADoms.insert(IDomA); 454 IDomA = IDomA->getIDom(); 455 } 456 457 // Walk NodeB immediate dominators chain and find common dominator node. 458 DomTreeNodeBase<NodeT> *IDomB = NodeB->getIDom(); 459 while(IDomB) { 460 if (NodeADoms.count(IDomB) != 0) 461 return IDomB->getBlock(); 462 463 IDomB = IDomB->getIDom(); 464 } 465 466 return NULL; 467 } 468 469 //===--------------------------------------------------------------------===// 470 // API to update (Post)DominatorTree information based on modifications to 471 // the CFG... 472 473 /// addNewBlock - Add a new node to the dominator tree information. This 474 /// creates a new node as a child of DomBB dominator node,linking it into 475 /// the children list of the immediate dominator. 476 DomTreeNodeBase<NodeT> *addNewBlock(NodeT *BB, NodeT *DomBB) { 477 assert(getNode(BB) == 0 && "Block already in dominator tree!"); 478 DomTreeNodeBase<NodeT> *IDomNode = getNode(DomBB); 479 assert(IDomNode && "Not immediate dominator specified for block!"); 480 DFSInfoValid = false; 481 return DomTreeNodes[BB] = 482 IDomNode->addChild(new DomTreeNodeBase<NodeT>(BB, IDomNode)); 483 } 484 485 /// changeImmediateDominator - This method is used to update the dominator 486 /// tree information when a node's immediate dominator changes. 487 /// 488 void changeImmediateDominator(DomTreeNodeBase<NodeT> *N, 489 DomTreeNodeBase<NodeT> *NewIDom) { 490 assert(N && NewIDom && "Cannot change null node pointers!"); 491 DFSInfoValid = false; 492 N->setIDom(NewIDom); 493 } 494 495 void changeImmediateDominator(NodeT *BB, NodeT *NewBB) { 496 changeImmediateDominator(getNode(BB), getNode(NewBB)); 497 } 498 499 /// eraseNode - Removes a node from the dominator tree. Block must not 500 /// domiante any other blocks. Removes node from its immediate dominator's 501 /// children list. Deletes dominator node associated with basic block BB. 502 void eraseNode(NodeT *BB) { 503 DomTreeNodeBase<NodeT> *Node = getNode(BB); 504 assert (Node && "Removing node that isn't in dominator tree."); 505 assert (Node->getChildren().empty() && "Node is not a leaf node."); 506 507 // Remove node from immediate dominator's children list. 508 DomTreeNodeBase<NodeT> *IDom = Node->getIDom(); 509 if (IDom) { 510 typename std::vector<DomTreeNodeBase<NodeT>*>::iterator I = 511 std::find(IDom->Children.begin(), IDom->Children.end(), Node); 512 assert(I != IDom->Children.end() && 513 "Not in immediate dominator children set!"); 514 // I am no longer your child... 515 IDom->Children.erase(I); 516 } 517 518 DomTreeNodes.erase(BB); 519 delete Node; 520 } 521 522 /// removeNode - Removes a node from the dominator tree. Block must not 523 /// dominate any other blocks. Invalidates any node pointing to removed 524 /// block. 525 void removeNode(NodeT *BB) { 526 assert(getNode(BB) && "Removing node that isn't in dominator tree."); 527 DomTreeNodes.erase(BB); 528 } 529 530 /// splitBlock - BB is split and now it has one successor. Update dominator 531 /// tree to reflect this change. 532 void splitBlock(NodeT* NewBB) { 533 if (this->IsPostDominators) 534 this->Split<Inverse<NodeT*>, GraphTraits<Inverse<NodeT*> > >(*this, NewBB); 535 else 536 this->Split<NodeT*, GraphTraits<NodeT*> >(*this, NewBB); 537 } 538 539 /// print - Convert to human readable form 540 /// 541 void print(raw_ostream &o) const { 542 o << "=============================--------------------------------\n"; 543 if (this->isPostDominator()) 544 o << "Inorder PostDominator Tree: "; 545 else 546 o << "Inorder Dominator Tree: "; 547 if (this->DFSInfoValid) 548 o << "DFSNumbers invalid: " << SlowQueries << " slow queries."; 549 o << "\n"; 550 551 PrintDomTree<NodeT>(getRootNode(), o, 1); 552 } 553 554protected: 555 template<class GraphT> 556 friend void Compress(DominatorTreeBase<typename GraphT::NodeType>& DT, 557 typename GraphT::NodeType* VIn); 558 559 template<class GraphT> 560 friend typename GraphT::NodeType* Eval( 561 DominatorTreeBase<typename GraphT::NodeType>& DT, 562 typename GraphT::NodeType* V); 563 564 template<class GraphT> 565 friend void Link(DominatorTreeBase<typename GraphT::NodeType>& DT, 566 unsigned DFSNumV, typename GraphT::NodeType* W, 567 typename DominatorTreeBase<typename GraphT::NodeType>::InfoRec &WInfo); 568 569 template<class GraphT> 570 friend unsigned DFSPass(DominatorTreeBase<typename GraphT::NodeType>& DT, 571 typename GraphT::NodeType* V, 572 unsigned N); 573 574 template<class FuncT, class N> 575 friend void Calculate(DominatorTreeBase<typename GraphTraits<N>::NodeType>& DT, 576 FuncT& F); 577 578 /// updateDFSNumbers - Assign In and Out numbers to the nodes while walking 579 /// dominator tree in dfs order. 580 void updateDFSNumbers() { 581 unsigned DFSNum = 0; 582 583 SmallVector<std::pair<DomTreeNodeBase<NodeT>*, 584 typename DomTreeNodeBase<NodeT>::iterator>, 32> WorkStack; 585 586 for (unsigned i = 0, e = (unsigned)this->Roots.size(); i != e; ++i) { 587 DomTreeNodeBase<NodeT> *ThisRoot = getNode(this->Roots[i]); 588 WorkStack.push_back(std::make_pair(ThisRoot, ThisRoot->begin())); 589 ThisRoot->DFSNumIn = DFSNum++; 590 591 while (!WorkStack.empty()) { 592 DomTreeNodeBase<NodeT> *Node = WorkStack.back().first; 593 typename DomTreeNodeBase<NodeT>::iterator ChildIt = 594 WorkStack.back().second; 595 596 // If we visited all of the children of this node, "recurse" back up the 597 // stack setting the DFOutNum. 598 if (ChildIt == Node->end()) { 599 Node->DFSNumOut = DFSNum++; 600 WorkStack.pop_back(); 601 } else { 602 // Otherwise, recursively visit this child. 603 DomTreeNodeBase<NodeT> *Child = *ChildIt; 604 ++WorkStack.back().second; 605 606 WorkStack.push_back(std::make_pair(Child, Child->begin())); 607 Child->DFSNumIn = DFSNum++; 608 } 609 } 610 } 611 612 SlowQueries = 0; 613 DFSInfoValid = true; 614 } 615 616 DomTreeNodeBase<NodeT> *getNodeForBlock(NodeT *BB) { 617 typename DomTreeNodeMapType::iterator I = this->DomTreeNodes.find(BB); 618 if (I != this->DomTreeNodes.end() && I->second) 619 return I->second; 620 621 // Haven't calculated this node yet? Get or calculate the node for the 622 // immediate dominator. 623 NodeT *IDom = getIDom(BB); 624 625 assert(IDom || this->DomTreeNodes[NULL]); 626 DomTreeNodeBase<NodeT> *IDomNode = getNodeForBlock(IDom); 627 628 // Add a new tree node for this BasicBlock, and link it as a child of 629 // IDomNode 630 DomTreeNodeBase<NodeT> *C = new DomTreeNodeBase<NodeT>(BB, IDomNode); 631 return this->DomTreeNodes[BB] = IDomNode->addChild(C); 632 } 633 634 inline NodeT *getIDom(NodeT *BB) const { 635 typename DenseMap<NodeT*, NodeT*>::const_iterator I = IDoms.find(BB); 636 return I != IDoms.end() ? I->second : 0; 637 } 638 639 inline void addRoot(NodeT* BB) { 640 this->Roots.push_back(BB); 641 } 642 643public: 644 /// recalculate - compute a dominator tree for the given function 645 template<class FT> 646 void recalculate(FT& F) { 647 if (!this->IsPostDominators) { 648 reset(); 649 650 // Initialize roots 651 this->Roots.push_back(&F.front()); 652 this->IDoms[&F.front()] = 0; 653 this->DomTreeNodes[&F.front()] = 0; 654 this->Vertex.push_back(0); 655 656 Calculate<FT, NodeT*>(*this, F); 657 658 updateDFSNumbers(); 659 } else { 660 reset(); // Reset from the last time we were run... 661 662 // Initialize the roots list 663 for (typename FT::iterator I = F.begin(), E = F.end(); I != E; ++I) { 664 if (std::distance(GraphTraits<FT*>::child_begin(I), 665 GraphTraits<FT*>::child_end(I)) == 0) 666 addRoot(I); 667 668 // Prepopulate maps so that we don't get iterator invalidation issues later. 669 this->IDoms[I] = 0; 670 this->DomTreeNodes[I] = 0; 671 } 672 673 this->Vertex.push_back(0); 674 675 Calculate<FT, Inverse<NodeT*> >(*this, F); 676 } 677 } 678}; 679 680EXTERN_TEMPLATE_INSTANTIATION(class DominatorTreeBase<BasicBlock>); 681 682//===------------------------------------- 683/// DominatorTree Class - Concrete subclass of DominatorTreeBase that is used to 684/// compute a normal dominator tree. 685/// 686class DominatorTree : public FunctionPass { 687public: 688 static char ID; // Pass ID, replacement for typeid 689 DominatorTreeBase<BasicBlock>* DT; 690 691 DominatorTree() : FunctionPass(&ID) { 692 DT = new DominatorTreeBase<BasicBlock>(false); 693 } 694 695 ~DominatorTree() { 696 DT->releaseMemory(); 697 delete DT; 698 } 699 700 DominatorTreeBase<BasicBlock>& getBase() { return *DT; } 701 702 /// getRoots - Return the root blocks of the current CFG. This may include 703 /// multiple blocks if we are computing post dominators. For forward 704 /// dominators, this will always be a single block (the entry node). 705 /// 706 inline const std::vector<BasicBlock*> &getRoots() const { 707 return DT->getRoots(); 708 } 709 710 inline BasicBlock *getRoot() const { 711 return DT->getRoot(); 712 } 713 714 inline DomTreeNode *getRootNode() const { 715 return DT->getRootNode(); 716 } 717 718 /// compare - Return false if the other dominator tree matches this 719 /// dominator tree. Otherwise return true. 720 inline bool compare(DominatorTree &Other) const { 721 DomTreeNode *R = getRootNode(); 722 DomTreeNode *OtherR = Other.getRootNode(); 723 724 if (!R || !OtherR || R->getBlock() != OtherR->getBlock()) 725 return true; 726 727 if (DT->compare(Other.getBase())) 728 return true; 729 730 return false; 731 } 732 733 virtual bool runOnFunction(Function &F); 734 735 virtual void getAnalysisUsage(AnalysisUsage &AU) const { 736 AU.setPreservesAll(); 737 } 738 739 inline bool dominates(DomTreeNode* A, DomTreeNode* B) const { 740 return DT->dominates(A, B); 741 } 742 743 inline bool dominates(const BasicBlock* A, const BasicBlock* B) const { 744 return DT->dominates(A, B); 745 } 746 747 // dominates - Return true if A dominates B. This performs the 748 // special checks necessary if A and B are in the same basic block. 749 bool dominates(const Instruction *A, const Instruction *B) const { 750 const BasicBlock *BBA = A->getParent(), *BBB = B->getParent(); 751 if (BBA != BBB) return dominates(BBA, BBB); 752 753 // It is not possible to determine dominance between two PHI nodes 754 // based on their ordering. 755 if (isa<PHINode>(A) && isa<PHINode>(B)) 756 return false; 757 758 // Loop through the basic block until we find A or B. 759 BasicBlock::const_iterator I = BBA->begin(); 760 for (; &*I != A && &*I != B; ++I) /*empty*/; 761 762 //if(!DT.IsPostDominators) { 763 // A dominates B if it is found first in the basic block. 764 return &*I == A; 765 //} else { 766 // // A post-dominates B if B is found first in the basic block. 767 // return &*I == B; 768 //} 769 } 770 771 inline bool properlyDominates(const DomTreeNode* A, 772 const DomTreeNode* B) const { 773 return DT->properlyDominates(A, B); 774 } 775 776 inline bool properlyDominates(BasicBlock* A, BasicBlock* B) const { 777 return DT->properlyDominates(A, B); 778 } 779 780 /// findNearestCommonDominator - Find nearest common dominator basic block 781 /// for basic block A and B. If there is no such block then return NULL. 782 inline BasicBlock *findNearestCommonDominator(BasicBlock *A, BasicBlock *B) { 783 return DT->findNearestCommonDominator(A, B); 784 } 785 786 inline DomTreeNode *operator[](BasicBlock *BB) const { 787 return DT->getNode(BB); 788 } 789 790 /// getNode - return the (Post)DominatorTree node for the specified basic 791 /// block. This is the same as using operator[] on this class. 792 /// 793 inline DomTreeNode *getNode(BasicBlock *BB) const { 794 return DT->getNode(BB); 795 } 796 797 /// addNewBlock - Add a new node to the dominator tree information. This 798 /// creates a new node as a child of DomBB dominator node,linking it into 799 /// the children list of the immediate dominator. 800 inline DomTreeNode *addNewBlock(BasicBlock *BB, BasicBlock *DomBB) { 801 return DT->addNewBlock(BB, DomBB); 802 } 803 804 /// changeImmediateDominator - This method is used to update the dominator 805 /// tree information when a node's immediate dominator changes. 806 /// 807 inline void changeImmediateDominator(BasicBlock *N, BasicBlock* NewIDom) { 808 DT->changeImmediateDominator(N, NewIDom); 809 } 810 811 inline void changeImmediateDominator(DomTreeNode *N, DomTreeNode* NewIDom) { 812 DT->changeImmediateDominator(N, NewIDom); 813 } 814 815 /// eraseNode - Removes a node from the dominator tree. Block must not 816 /// domiante any other blocks. Removes node from its immediate dominator's 817 /// children list. Deletes dominator node associated with basic block BB. 818 inline void eraseNode(BasicBlock *BB) { 819 DT->eraseNode(BB); 820 } 821 822 /// splitBlock - BB is split and now it has one successor. Update dominator 823 /// tree to reflect this change. 824 inline void splitBlock(BasicBlock* NewBB) { 825 DT->splitBlock(NewBB); 826 } 827 828 bool isReachableFromEntry(BasicBlock* A) { 829 return DT->isReachableFromEntry(A); 830 } 831 832 833 virtual void releaseMemory() { 834 DT->releaseMemory(); 835 } 836 837 virtual void print(raw_ostream &OS, const Module* M= 0) const; 838}; 839 840//===------------------------------------- 841/// DominatorTree GraphTraits specialization so the DominatorTree can be 842/// iterable by generic graph iterators. 843/// 844template <> struct GraphTraits<DomTreeNode *> { 845 typedef DomTreeNode NodeType; 846 typedef NodeType::iterator ChildIteratorType; 847 848 static NodeType *getEntryNode(NodeType *N) { 849 return N; 850 } 851 static inline ChildIteratorType child_begin(NodeType* N) { 852 return N->begin(); 853 } 854 static inline ChildIteratorType child_end(NodeType* N) { 855 return N->end(); 856 } 857}; 858 859template <> struct GraphTraits<DominatorTree*> 860 : public GraphTraits<DomTreeNode *> { 861 static NodeType *getEntryNode(DominatorTree *DT) { 862 return DT->getRootNode(); 863 } 864}; 865 866 867//===----------------------------------------------------------------------===// 868/// DominanceFrontierBase - Common base class for computing forward and inverse 869/// dominance frontiers for a function. 870/// 871class DominanceFrontierBase : public FunctionPass { 872public: 873 typedef std::set<BasicBlock*> DomSetType; // Dom set for a bb 874 typedef std::map<BasicBlock*, DomSetType> DomSetMapType; // Dom set map 875protected: 876 DomSetMapType Frontiers; 877 std::vector<BasicBlock*> Roots; 878 const bool IsPostDominators; 879 880public: 881 DominanceFrontierBase(void *ID, bool isPostDom) 882 : FunctionPass(ID), IsPostDominators(isPostDom) {} 883 884 /// getRoots - Return the root blocks of the current CFG. This may include 885 /// multiple blocks if we are computing post dominators. For forward 886 /// dominators, this will always be a single block (the entry node). 887 /// 888 inline const std::vector<BasicBlock*> &getRoots() const { return Roots; } 889 890 /// isPostDominator - Returns true if analysis based of postdoms 891 /// 892 bool isPostDominator() const { return IsPostDominators; } 893 894 virtual void releaseMemory() { Frontiers.clear(); } 895 896 // Accessor interface: 897 typedef DomSetMapType::iterator iterator; 898 typedef DomSetMapType::const_iterator const_iterator; 899 iterator begin() { return Frontiers.begin(); } 900 const_iterator begin() const { return Frontiers.begin(); } 901 iterator end() { return Frontiers.end(); } 902 const_iterator end() const { return Frontiers.end(); } 903 iterator find(BasicBlock *B) { return Frontiers.find(B); } 904 const_iterator find(BasicBlock *B) const { return Frontiers.find(B); } 905 906 void addBasicBlock(BasicBlock *BB, const DomSetType &frontier) { 907 assert(find(BB) == end() && "Block already in DominanceFrontier!"); 908 Frontiers.insert(std::make_pair(BB, frontier)); 909 } 910 911 /// removeBlock - Remove basic block BB's frontier. 912 void removeBlock(BasicBlock *BB) { 913 assert(find(BB) != end() && "Block is not in DominanceFrontier!"); 914 for (iterator I = begin(), E = end(); I != E; ++I) 915 I->second.erase(BB); 916 Frontiers.erase(BB); 917 } 918 919 void addToFrontier(iterator I, BasicBlock *Node) { 920 assert(I != end() && "BB is not in DominanceFrontier!"); 921 I->second.insert(Node); 922 } 923 924 void removeFromFrontier(iterator I, BasicBlock *Node) { 925 assert(I != end() && "BB is not in DominanceFrontier!"); 926 assert(I->second.count(Node) && "Node is not in DominanceFrontier of BB"); 927 I->second.erase(Node); 928 } 929 930 /// compareDomSet - Return false if two domsets match. Otherwise 931 /// return true; 932 bool compareDomSet(DomSetType &DS1, const DomSetType &DS2) const { 933 std::set<BasicBlock *> tmpSet; 934 for (DomSetType::const_iterator I = DS2.begin(), 935 E = DS2.end(); I != E; ++I) 936 tmpSet.insert(*I); 937 938 for (DomSetType::const_iterator I = DS1.begin(), 939 E = DS1.end(); I != E; ) { 940 BasicBlock *Node = *I++; 941 942 if (tmpSet.erase(Node) == 0) 943 // Node is in DS1 but not in DS2. 944 return true; 945 } 946 947 if(!tmpSet.empty()) 948 // There are nodes that are in DS2 but not in DS1. 949 return true; 950 951 // DS1 and DS2 matches. 952 return false; 953 } 954 955 /// compare - Return true if the other dominance frontier base matches 956 /// this dominance frontier base. Otherwise return false. 957 bool compare(DominanceFrontierBase &Other) const { 958 DomSetMapType tmpFrontiers; 959 for (DomSetMapType::const_iterator I = Other.begin(), 960 E = Other.end(); I != E; ++I) 961 tmpFrontiers.insert(std::make_pair(I->first, I->second)); 962 963 for (DomSetMapType::iterator I = tmpFrontiers.begin(), 964 E = tmpFrontiers.end(); I != E; ) { 965 BasicBlock *Node = I->first; 966 const_iterator DFI = find(Node); 967 if (DFI == end()) 968 return true; 969 970 if (compareDomSet(I->second, DFI->second)) 971 return true; 972 973 ++I; 974 tmpFrontiers.erase(Node); 975 } 976 977 if (!tmpFrontiers.empty()) 978 return true; 979 980 return false; 981 } 982 983 /// print - Convert to human readable form 984 /// 985 virtual void print(raw_ostream &OS, const Module* = 0) const; 986}; 987 988 989//===------------------------------------- 990/// DominanceFrontier Class - Concrete subclass of DominanceFrontierBase that is 991/// used to compute a forward dominator frontiers. 992/// 993class DominanceFrontier : public DominanceFrontierBase { 994public: 995 static char ID; // Pass ID, replacement for typeid 996 DominanceFrontier() : 997 DominanceFrontierBase(&ID, false) {} 998 999 BasicBlock *getRoot() const { 1000 assert(Roots.size() == 1 && "Should always have entry node!"); 1001 return Roots[0]; 1002 } 1003 1004 virtual bool runOnFunction(Function &) { 1005 Frontiers.clear(); 1006 DominatorTree &DT = getAnalysis<DominatorTree>(); 1007 Roots = DT.getRoots(); 1008 assert(Roots.size() == 1 && "Only one entry block for forward domfronts!"); 1009 calculate(DT, DT[Roots[0]]); 1010 return false; 1011 } 1012 1013 virtual void getAnalysisUsage(AnalysisUsage &AU) const { 1014 AU.setPreservesAll(); 1015 AU.addRequired<DominatorTree>(); 1016 } 1017 1018 /// splitBlock - BB is split and now it has one successor. Update dominance 1019 /// frontier to reflect this change. 1020 void splitBlock(BasicBlock *BB); 1021 1022 /// BasicBlock BB's new dominator is NewBB. Update BB's dominance frontier 1023 /// to reflect this change. 1024 void changeImmediateDominator(BasicBlock *BB, BasicBlock *NewBB, 1025 DominatorTree *DT) { 1026 // NewBB is now dominating BB. Which means BB's dominance 1027 // frontier is now part of NewBB's dominance frontier. However, BB 1028 // itself is not member of NewBB's dominance frontier. 1029 DominanceFrontier::iterator NewDFI = find(NewBB); 1030 DominanceFrontier::iterator DFI = find(BB); 1031 // If BB was an entry block then its frontier is empty. 1032 if (DFI == end()) 1033 return; 1034 DominanceFrontier::DomSetType BBSet = DFI->second; 1035 for (DominanceFrontier::DomSetType::iterator BBSetI = BBSet.begin(), 1036 BBSetE = BBSet.end(); BBSetI != BBSetE; ++BBSetI) { 1037 BasicBlock *DFMember = *BBSetI; 1038 // Insert only if NewBB dominates DFMember. 1039 if (!DT->dominates(NewBB, DFMember)) 1040 NewDFI->second.insert(DFMember); 1041 } 1042 NewDFI->second.erase(BB); 1043 } 1044 1045 const DomSetType &calculate(const DominatorTree &DT, 1046 const DomTreeNode *Node); 1047}; 1048 1049 1050} // End llvm namespace 1051 1052#endif 1053