Dominators.h revision 0a8fe7a2458f0412bce1ed282fd1a3ca6fdc51bc
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/BasicBlock.h" 26#include "llvm/Function.h" 27#include "llvm/Instructions.h" 28#include "llvm/ADT/DenseMap.h" 29#include "llvm/ADT/GraphTraits.h" 30#include "llvm/ADT/SmallPtrSet.h" 31#include "llvm/ADT/SmallVector.h" 32#include "llvm/Assembly/Writer.h" 33#include "llvm/Support/CFG.h" 34#include "llvm/Support/Compiler.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 std::ostream &operator<<(std::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, std::ostream &o, 178 unsigned Lev) { 179 o << std::string(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 // The newly inserted basic block will dominate existing basic blocks iff the 255 // PredBlocks dominate all of the non-pred blocks. If all predblocks dominate 256 // the non-pred blocks, then they all must be the same block! 257 // 258 bool NewBBDominatesNewBBSucc = true; 259 { 260 typename GraphT::NodeType* OnePred = PredBlocks[0]; 261 size_t i = 1, e = PredBlocks.size(); 262 for (i = 1; !DT.isReachableFromEntry(OnePred); ++i) { 263 assert(i != e && "Didn't find reachable pred?"); 264 OnePred = PredBlocks[i]; 265 } 266 267 for (; i != e; ++i) 268 if (PredBlocks[i] != OnePred && DT.isReachableFromEntry(OnePred)) { 269 NewBBDominatesNewBBSucc = false; 270 break; 271 } 272 273 if (NewBBDominatesNewBBSucc) 274 for (typename GraphTraits<Inverse<N> >::ChildIteratorType PI = 275 GraphTraits<Inverse<N> >::child_begin(NewBBSucc), 276 E = GraphTraits<Inverse<N> >::child_end(NewBBSucc); PI != E; ++PI) 277 if (*PI != NewBB && !DT.dominates(NewBBSucc, *PI)) { 278 NewBBDominatesNewBBSucc = false; 279 break; 280 } 281 } 282 283 // The other scenario where the new block can dominate its successors are when 284 // all predecessors of NewBBSucc that are not NewBB are dominated by NewBBSucc 285 // already. 286 if (!NewBBDominatesNewBBSucc) { 287 NewBBDominatesNewBBSucc = true; 288 for (typename GraphTraits<Inverse<N> >::ChildIteratorType PI = 289 GraphTraits<Inverse<N> >::child_begin(NewBBSucc), 290 E = GraphTraits<Inverse<N> >::child_end(NewBBSucc); PI != E; ++PI) 291 if (*PI != NewBB && !DT.dominates(NewBBSucc, *PI)) { 292 NewBBDominatesNewBBSucc = false; 293 break; 294 } 295 } 296 297 // Find NewBB's immediate dominator and create new dominator tree node for 298 // NewBB. 299 NodeT *NewBBIDom = 0; 300 unsigned i = 0; 301 for (i = 0; i < PredBlocks.size(); ++i) 302 if (DT.isReachableFromEntry(PredBlocks[i])) { 303 NewBBIDom = PredBlocks[i]; 304 break; 305 } 306 assert(i != PredBlocks.size() && "No reachable preds?"); 307 for (i = i + 1; i < PredBlocks.size(); ++i) { 308 if (DT.isReachableFromEntry(PredBlocks[i])) 309 NewBBIDom = DT.findNearestCommonDominator(NewBBIDom, PredBlocks[i]); 310 } 311 assert(NewBBIDom && "No immediate dominator found??"); 312 313 // Create the new dominator tree node... and set the idom of NewBB. 314 DomTreeNodeBase<NodeT> *NewBBNode = DT.addNewBlock(NewBB, NewBBIDom); 315 316 // If NewBB strictly dominates other blocks, then it is now the immediate 317 // dominator of NewBBSucc. Update the dominator tree as appropriate. 318 if (NewBBDominatesNewBBSucc) { 319 DomTreeNodeBase<NodeT> *NewBBSuccNode = DT.getNode(NewBBSucc); 320 DT.changeImmediateDominator(NewBBSuccNode, NewBBNode); 321 } 322 } 323 324public: 325 explicit DominatorTreeBase(bool isPostDom) 326 : DominatorBase<NodeT>(isPostDom), DFSInfoValid(false), SlowQueries(0) {} 327 virtual ~DominatorTreeBase() { reset(); } 328 329 // FIXME: Should remove this 330 virtual bool runOnFunction(Function &F) { return false; } 331 332 /// compare - Return false if the other dominator tree base matches this 333 /// dominator tree base. Otherwise return true. 334 bool compare(DominatorTreeBase &Other) const { 335 336 const DomTreeNodeMapType &OtherDomTreeNodes = Other.DomTreeNodes; 337 if (DomTreeNodes.size() != OtherDomTreeNodes.size()) 338 return true; 339 340 SmallPtrSet<const NodeT *,4> MyBBs; 341 for (typename DomTreeNodeMapType::const_iterator 342 I = this->DomTreeNodes.begin(), 343 E = this->DomTreeNodes.end(); I != E; ++I) { 344 NodeT *BB = I->first; 345 typename DomTreeNodeMapType::const_iterator OI = OtherDomTreeNodes.find(BB); 346 if (OI == OtherDomTreeNodes.end()) 347 return true; 348 349 DomTreeNodeBase<NodeT>* MyNd = I->second; 350 DomTreeNodeBase<NodeT>* OtherNd = OI->second; 351 352 if (MyNd->compare(OtherNd)) 353 return true; 354 } 355 356 return false; 357 } 358 359 virtual void releaseMemory() { reset(); } 360 361 /// getNode - return the (Post)DominatorTree node for the specified basic 362 /// block. This is the same as using operator[] on this class. 363 /// 364 inline DomTreeNodeBase<NodeT> *getNode(NodeT *BB) const { 365 typename DomTreeNodeMapType::const_iterator I = DomTreeNodes.find(BB); 366 return I != DomTreeNodes.end() ? I->second : 0; 367 } 368 369 /// getRootNode - This returns the entry node for the CFG of the function. If 370 /// this tree represents the post-dominance relations for a function, however, 371 /// this root may be a node with the block == NULL. This is the case when 372 /// there are multiple exit nodes from a particular function. Consumers of 373 /// post-dominance information must be capable of dealing with this 374 /// possibility. 375 /// 376 DomTreeNodeBase<NodeT> *getRootNode() { return RootNode; } 377 const DomTreeNodeBase<NodeT> *getRootNode() const { return RootNode; } 378 379 /// properlyDominates - Returns true iff this dominates N and this != N. 380 /// Note that this is not a constant time operation! 381 /// 382 bool properlyDominates(const DomTreeNodeBase<NodeT> *A, 383 DomTreeNodeBase<NodeT> *B) const { 384 if (A == 0 || B == 0) return false; 385 return dominatedBySlowTreeWalk(A, B); 386 } 387 388 inline bool properlyDominates(NodeT *A, NodeT *B) { 389 return properlyDominates(getNode(A), getNode(B)); 390 } 391 392 bool dominatedBySlowTreeWalk(const DomTreeNodeBase<NodeT> *A, 393 const DomTreeNodeBase<NodeT> *B) const { 394 const DomTreeNodeBase<NodeT> *IDom; 395 if (A == 0 || B == 0) return false; 396 while ((IDom = B->getIDom()) != 0 && IDom != A && IDom != B) 397 B = IDom; // Walk up the tree 398 return IDom != 0; 399 } 400 401 402 /// isReachableFromEntry - Return true if A is dominated by the entry 403 /// block of the function containing it. 404 bool isReachableFromEntry(NodeT* A) { 405 assert (!this->isPostDominator() 406 && "This is not implemented for post dominators"); 407 return dominates(&A->getParent()->front(), A); 408 } 409 410 /// dominates - Returns true iff A dominates B. Note that this is not a 411 /// constant time operation! 412 /// 413 inline bool dominates(const DomTreeNodeBase<NodeT> *A, 414 DomTreeNodeBase<NodeT> *B) { 415 if (B == A) 416 return true; // A node trivially dominates itself. 417 418 if (A == 0 || B == 0) 419 return false; 420 421 if (DFSInfoValid) 422 return B->DominatedBy(A); 423 424 // If we end up with too many slow queries, just update the 425 // DFS numbers on the theory that we are going to keep querying. 426 SlowQueries++; 427 if (SlowQueries > 32) { 428 updateDFSNumbers(); 429 return B->DominatedBy(A); 430 } 431 432 return dominatedBySlowTreeWalk(A, B); 433 } 434 435 inline bool dominates(NodeT *A, NodeT *B) { 436 if (A == B) 437 return true; 438 439 return dominates(getNode(A), getNode(B)); 440 } 441 442 NodeT *getRoot() const { 443 assert(this->Roots.size() == 1 && "Should always have entry node!"); 444 return this->Roots[0]; 445 } 446 447 /// findNearestCommonDominator - Find nearest common dominator basic block 448 /// for basic block A and B. If there is no such block then return NULL. 449 NodeT *findNearestCommonDominator(NodeT *A, NodeT *B) { 450 451 assert (!this->isPostDominator() 452 && "This is not implemented for post dominators"); 453 assert (A->getParent() == B->getParent() 454 && "Two blocks are not in same function"); 455 456 // If either A or B is a entry block then it is nearest common dominator. 457 NodeT &Entry = A->getParent()->front(); 458 if (A == &Entry || B == &Entry) 459 return &Entry; 460 461 // If B dominates A then B is nearest common dominator. 462 if (dominates(B, A)) 463 return B; 464 465 // If A dominates B then A is nearest common dominator. 466 if (dominates(A, B)) 467 return A; 468 469 DomTreeNodeBase<NodeT> *NodeA = getNode(A); 470 DomTreeNodeBase<NodeT> *NodeB = getNode(B); 471 472 // Collect NodeA dominators set. 473 SmallPtrSet<DomTreeNodeBase<NodeT>*, 16> NodeADoms; 474 NodeADoms.insert(NodeA); 475 DomTreeNodeBase<NodeT> *IDomA = NodeA->getIDom(); 476 while (IDomA) { 477 NodeADoms.insert(IDomA); 478 IDomA = IDomA->getIDom(); 479 } 480 481 // Walk NodeB immediate dominators chain and find common dominator node. 482 DomTreeNodeBase<NodeT> *IDomB = NodeB->getIDom(); 483 while(IDomB) { 484 if (NodeADoms.count(IDomB) != 0) 485 return IDomB->getBlock(); 486 487 IDomB = IDomB->getIDom(); 488 } 489 490 return NULL; 491 } 492 493 //===--------------------------------------------------------------------===// 494 // API to update (Post)DominatorTree information based on modifications to 495 // the CFG... 496 497 /// addNewBlock - Add a new node to the dominator tree information. This 498 /// creates a new node as a child of DomBB dominator node,linking it into 499 /// the children list of the immediate dominator. 500 DomTreeNodeBase<NodeT> *addNewBlock(NodeT *BB, NodeT *DomBB) { 501 assert(getNode(BB) == 0 && "Block already in dominator tree!"); 502 DomTreeNodeBase<NodeT> *IDomNode = getNode(DomBB); 503 assert(IDomNode && "Not immediate dominator specified for block!"); 504 DFSInfoValid = false; 505 return DomTreeNodes[BB] = 506 IDomNode->addChild(new DomTreeNodeBase<NodeT>(BB, IDomNode)); 507 } 508 509 /// changeImmediateDominator - This method is used to update the dominator 510 /// tree information when a node's immediate dominator changes. 511 /// 512 void changeImmediateDominator(DomTreeNodeBase<NodeT> *N, 513 DomTreeNodeBase<NodeT> *NewIDom) { 514 assert(N && NewIDom && "Cannot change null node pointers!"); 515 DFSInfoValid = false; 516 N->setIDom(NewIDom); 517 } 518 519 void changeImmediateDominator(NodeT *BB, NodeT *NewBB) { 520 changeImmediateDominator(getNode(BB), getNode(NewBB)); 521 } 522 523 /// eraseNode - Removes a node from the dominator tree. Block must not 524 /// domiante any other blocks. Removes node from its immediate dominator's 525 /// children list. Deletes dominator node associated with basic block BB. 526 void eraseNode(NodeT *BB) { 527 DomTreeNodeBase<NodeT> *Node = getNode(BB); 528 assert (Node && "Removing node that isn't in dominator tree."); 529 assert (Node->getChildren().empty() && "Node is not a leaf node."); 530 531 // Remove node from immediate dominator's children list. 532 DomTreeNodeBase<NodeT> *IDom = Node->getIDom(); 533 if (IDom) { 534 typename std::vector<DomTreeNodeBase<NodeT>*>::iterator I = 535 std::find(IDom->Children.begin(), IDom->Children.end(), Node); 536 assert(I != IDom->Children.end() && 537 "Not in immediate dominator children set!"); 538 // I am no longer your child... 539 IDom->Children.erase(I); 540 } 541 542 DomTreeNodes.erase(BB); 543 delete Node; 544 } 545 546 /// removeNode - Removes a node from the dominator tree. Block must not 547 /// dominate any other blocks. Invalidates any node pointing to removed 548 /// block. 549 void removeNode(NodeT *BB) { 550 assert(getNode(BB) && "Removing node that isn't in dominator tree."); 551 DomTreeNodes.erase(BB); 552 } 553 554 /// splitBlock - BB is split and now it has one successor. Update dominator 555 /// tree to reflect this change. 556 void splitBlock(NodeT* NewBB) { 557 if (this->IsPostDominators) 558 this->Split<Inverse<NodeT*>, GraphTraits<Inverse<NodeT*> > >(*this, NewBB); 559 else 560 this->Split<NodeT*, GraphTraits<NodeT*> >(*this, NewBB); 561 } 562 563 /// print - Convert to human readable form 564 /// 565 virtual void print(std::ostream &o, const Module* ) const { 566 o << "=============================--------------------------------\n"; 567 if (this->isPostDominator()) 568 o << "Inorder PostDominator Tree: "; 569 else 570 o << "Inorder Dominator Tree: "; 571 if (this->DFSInfoValid) 572 o << "DFSNumbers invalid: " << SlowQueries << " slow queries."; 573 o << "\n"; 574 575 PrintDomTree<NodeT>(getRootNode(), o, 1); 576 } 577 578 void print(std::ostream *OS, const Module* M = 0) const { 579 if (OS) print(*OS, M); 580 } 581 582 virtual void dump() { 583 print(llvm::cerr); 584 } 585 586protected: 587 template<class GraphT> 588 friend void Compress(DominatorTreeBase<typename GraphT::NodeType>& DT, 589 typename GraphT::NodeType* VIn); 590 591 template<class GraphT> 592 friend typename GraphT::NodeType* Eval( 593 DominatorTreeBase<typename GraphT::NodeType>& DT, 594 typename GraphT::NodeType* V); 595 596 template<class GraphT> 597 friend void Link(DominatorTreeBase<typename GraphT::NodeType>& DT, 598 unsigned DFSNumV, typename GraphT::NodeType* W, 599 typename DominatorTreeBase<typename GraphT::NodeType>::InfoRec &WInfo); 600 601 template<class GraphT> 602 friend unsigned DFSPass(DominatorTreeBase<typename GraphT::NodeType>& DT, 603 typename GraphT::NodeType* V, 604 unsigned N); 605 606 template<class FuncT, class N> 607 friend void Calculate(DominatorTreeBase<typename GraphTraits<N>::NodeType>& DT, 608 FuncT& F); 609 610 /// updateDFSNumbers - Assign In and Out numbers to the nodes while walking 611 /// dominator tree in dfs order. 612 void updateDFSNumbers() { 613 unsigned DFSNum = 0; 614 615 SmallVector<std::pair<DomTreeNodeBase<NodeT>*, 616 typename DomTreeNodeBase<NodeT>::iterator>, 32> WorkStack; 617 618 for (unsigned i = 0, e = (unsigned)this->Roots.size(); i != e; ++i) { 619 DomTreeNodeBase<NodeT> *ThisRoot = getNode(this->Roots[i]); 620 WorkStack.push_back(std::make_pair(ThisRoot, ThisRoot->begin())); 621 ThisRoot->DFSNumIn = DFSNum++; 622 623 while (!WorkStack.empty()) { 624 DomTreeNodeBase<NodeT> *Node = WorkStack.back().first; 625 typename DomTreeNodeBase<NodeT>::iterator ChildIt = 626 WorkStack.back().second; 627 628 // If we visited all of the children of this node, "recurse" back up the 629 // stack setting the DFOutNum. 630 if (ChildIt == Node->end()) { 631 Node->DFSNumOut = DFSNum++; 632 WorkStack.pop_back(); 633 } else { 634 // Otherwise, recursively visit this child. 635 DomTreeNodeBase<NodeT> *Child = *ChildIt; 636 ++WorkStack.back().second; 637 638 WorkStack.push_back(std::make_pair(Child, Child->begin())); 639 Child->DFSNumIn = DFSNum++; 640 } 641 } 642 } 643 644 SlowQueries = 0; 645 DFSInfoValid = true; 646 } 647 648 DomTreeNodeBase<NodeT> *getNodeForBlock(NodeT *BB) { 649 if (DomTreeNodeBase<NodeT> *BBNode = this->DomTreeNodes[BB]) 650 return BBNode; 651 652 // Haven't calculated this node yet? Get or calculate the node for the 653 // immediate dominator. 654 NodeT *IDom = getIDom(BB); 655 656 assert(IDom || this->DomTreeNodes[NULL]); 657 DomTreeNodeBase<NodeT> *IDomNode = getNodeForBlock(IDom); 658 659 // Add a new tree node for this BasicBlock, and link it as a child of 660 // IDomNode 661 DomTreeNodeBase<NodeT> *C = new DomTreeNodeBase<NodeT>(BB, IDomNode); 662 return this->DomTreeNodes[BB] = IDomNode->addChild(C); 663 } 664 665 inline NodeT *getIDom(NodeT *BB) const { 666 typename DenseMap<NodeT*, NodeT*>::const_iterator I = IDoms.find(BB); 667 return I != IDoms.end() ? I->second : 0; 668 } 669 670 inline void addRoot(NodeT* BB) { 671 this->Roots.push_back(BB); 672 } 673 674public: 675 /// recalculate - compute a dominator tree for the given function 676 template<class FT> 677 void recalculate(FT& F) { 678 if (!this->IsPostDominators) { 679 reset(); 680 681 // Initialize roots 682 this->Roots.push_back(&F.front()); 683 this->IDoms[&F.front()] = 0; 684 this->DomTreeNodes[&F.front()] = 0; 685 this->Vertex.push_back(0); 686 687 Calculate<FT, NodeT*>(*this, F); 688 689 updateDFSNumbers(); 690 } else { 691 reset(); // Reset from the last time we were run... 692 693 // Initialize the roots list 694 for (typename FT::iterator I = F.begin(), E = F.end(); I != E; ++I) { 695 if (std::distance(GraphTraits<FT*>::child_begin(I), 696 GraphTraits<FT*>::child_end(I)) == 0) 697 addRoot(I); 698 699 // Prepopulate maps so that we don't get iterator invalidation issues later. 700 this->IDoms[I] = 0; 701 this->DomTreeNodes[I] = 0; 702 } 703 704 this->Vertex.push_back(0); 705 706 Calculate<FT, Inverse<NodeT*> >(*this, F); 707 } 708 } 709}; 710 711EXTERN_TEMPLATE_INSTANTIATION(class DominatorTreeBase<BasicBlock>); 712 713//===------------------------------------- 714/// DominatorTree Class - Concrete subclass of DominatorTreeBase that is used to 715/// compute a normal dominator tree. 716/// 717class DominatorTree : public FunctionPass { 718public: 719 static char ID; // Pass ID, replacement for typeid 720 DominatorTreeBase<BasicBlock>* DT; 721 722 DominatorTree() : FunctionPass(&ID) { 723 DT = new DominatorTreeBase<BasicBlock>(false); 724 } 725 726 ~DominatorTree() { 727 DT->releaseMemory(); 728 delete DT; 729 } 730 731 DominatorTreeBase<BasicBlock>& getBase() { return *DT; } 732 733 /// getRoots - Return the root blocks of the current CFG. This may include 734 /// multiple blocks if we are computing post dominators. For forward 735 /// dominators, this will always be a single block (the entry node). 736 /// 737 inline const std::vector<BasicBlock*> &getRoots() const { 738 return DT->getRoots(); 739 } 740 741 inline BasicBlock *getRoot() const { 742 return DT->getRoot(); 743 } 744 745 inline DomTreeNode *getRootNode() const { 746 return DT->getRootNode(); 747 } 748 749 /// compare - Return false if the other dominator tree matches this 750 /// dominator tree. Otherwise return true. 751 inline bool compare(DominatorTree &Other) const { 752 DomTreeNode *R = getRootNode(); 753 DomTreeNode *OtherR = Other.getRootNode(); 754 755 if (!R || !OtherR || R->getBlock() != OtherR->getBlock()) 756 return true; 757 758 if (DT->compare(Other.getBase())) 759 return true; 760 761 return false; 762 } 763 764 virtual bool runOnFunction(Function &F); 765 766 virtual void getAnalysisUsage(AnalysisUsage &AU) const { 767 AU.setPreservesAll(); 768 } 769 770 inline bool dominates(DomTreeNode* A, DomTreeNode* B) const { 771 return DT->dominates(A, B); 772 } 773 774 inline bool dominates(BasicBlock* A, BasicBlock* B) const { 775 return DT->dominates(A, B); 776 } 777 778 // dominates - Return true if A dominates B. This performs the 779 // special checks necessary if A and B are in the same basic block. 780 bool dominates(Instruction *A, Instruction *B) const { 781 BasicBlock *BBA = A->getParent(), *BBB = B->getParent(); 782 if (BBA != BBB) return DT->dominates(BBA, BBB); 783 784 // It is not possible to determine dominance between two PHI nodes 785 // based on their ordering. 786 if (isa<PHINode>(A) && isa<PHINode>(B)) 787 return false; 788 789 // Loop through the basic block until we find A or B. 790 BasicBlock::iterator I = BBA->begin(); 791 for (; &*I != A && &*I != B; ++I) /*empty*/; 792 793 //if(!DT.IsPostDominators) { 794 // A dominates B if it is found first in the basic block. 795 return &*I == A; 796 //} else { 797 // // A post-dominates B if B is found first in the basic block. 798 // return &*I == B; 799 //} 800 } 801 802 inline bool properlyDominates(const DomTreeNode* A, DomTreeNode* B) const { 803 return DT->properlyDominates(A, B); 804 } 805 806 inline bool properlyDominates(BasicBlock* A, BasicBlock* B) const { 807 return DT->properlyDominates(A, B); 808 } 809 810 /// findNearestCommonDominator - Find nearest common dominator basic block 811 /// for basic block A and B. If there is no such block then return NULL. 812 inline BasicBlock *findNearestCommonDominator(BasicBlock *A, BasicBlock *B) { 813 return DT->findNearestCommonDominator(A, B); 814 } 815 816 inline DomTreeNode *operator[](BasicBlock *BB) const { 817 return DT->getNode(BB); 818 } 819 820 /// getNode - return the (Post)DominatorTree node for the specified basic 821 /// block. This is the same as using operator[] on this class. 822 /// 823 inline DomTreeNode *getNode(BasicBlock *BB) const { 824 return DT->getNode(BB); 825 } 826 827 /// addNewBlock - Add a new node to the dominator tree information. This 828 /// creates a new node as a child of DomBB dominator node,linking it into 829 /// the children list of the immediate dominator. 830 inline DomTreeNode *addNewBlock(BasicBlock *BB, BasicBlock *DomBB) { 831 return DT->addNewBlock(BB, DomBB); 832 } 833 834 /// changeImmediateDominator - This method is used to update the dominator 835 /// tree information when a node's immediate dominator changes. 836 /// 837 inline void changeImmediateDominator(BasicBlock *N, BasicBlock* NewIDom) { 838 DT->changeImmediateDominator(N, NewIDom); 839 } 840 841 inline void changeImmediateDominator(DomTreeNode *N, DomTreeNode* NewIDom) { 842 DT->changeImmediateDominator(N, NewIDom); 843 } 844 845 /// eraseNode - Removes a node from the dominator tree. Block must not 846 /// domiante any other blocks. Removes node from its immediate dominator's 847 /// children list. Deletes dominator node associated with basic block BB. 848 inline void eraseNode(BasicBlock *BB) { 849 DT->eraseNode(BB); 850 } 851 852 /// splitBlock - BB is split and now it has one successor. Update dominator 853 /// tree to reflect this change. 854 inline void splitBlock(BasicBlock* NewBB) { 855 DT->splitBlock(NewBB); 856 } 857 858 bool isReachableFromEntry(BasicBlock* A) { 859 return DT->isReachableFromEntry(A); 860 } 861 862 863 virtual void releaseMemory() { 864 DT->releaseMemory(); 865 } 866 867 virtual void print(std::ostream &OS, const Module* M= 0) const { 868 DT->print(OS, M); 869 } 870}; 871 872//===------------------------------------- 873/// DominatorTree GraphTraits specialization so the DominatorTree can be 874/// iterable by generic graph iterators. 875/// 876template <> struct GraphTraits<DomTreeNode *> { 877 typedef DomTreeNode NodeType; 878 typedef NodeType::iterator ChildIteratorType; 879 880 static NodeType *getEntryNode(NodeType *N) { 881 return N; 882 } 883 static inline ChildIteratorType child_begin(NodeType* N) { 884 return N->begin(); 885 } 886 static inline ChildIteratorType child_end(NodeType* N) { 887 return N->end(); 888 } 889}; 890 891template <> struct GraphTraits<DominatorTree*> 892 : public GraphTraits<DomTreeNode *> { 893 static NodeType *getEntryNode(DominatorTree *DT) { 894 return DT->getRootNode(); 895 } 896}; 897 898 899//===----------------------------------------------------------------------===// 900/// DominanceFrontierBase - Common base class for computing forward and inverse 901/// dominance frontiers for a function. 902/// 903class DominanceFrontierBase : public FunctionPass { 904public: 905 typedef std::set<BasicBlock*> DomSetType; // Dom set for a bb 906 typedef std::map<BasicBlock*, DomSetType> DomSetMapType; // Dom set map 907protected: 908 DomSetMapType Frontiers; 909 std::vector<BasicBlock*> Roots; 910 const bool IsPostDominators; 911 912public: 913 DominanceFrontierBase(void *ID, bool isPostDom) 914 : FunctionPass(ID), IsPostDominators(isPostDom) {} 915 916 /// getRoots - Return the root blocks of the current CFG. This may include 917 /// multiple blocks if we are computing post dominators. For forward 918 /// dominators, this will always be a single block (the entry node). 919 /// 920 inline const std::vector<BasicBlock*> &getRoots() const { return Roots; } 921 922 /// isPostDominator - Returns true if analysis based of postdoms 923 /// 924 bool isPostDominator() const { return IsPostDominators; } 925 926 virtual void releaseMemory() { Frontiers.clear(); } 927 928 // Accessor interface: 929 typedef DomSetMapType::iterator iterator; 930 typedef DomSetMapType::const_iterator const_iterator; 931 iterator begin() { return Frontiers.begin(); } 932 const_iterator begin() const { return Frontiers.begin(); } 933 iterator end() { return Frontiers.end(); } 934 const_iterator end() const { return Frontiers.end(); } 935 iterator find(BasicBlock *B) { return Frontiers.find(B); } 936 const_iterator find(BasicBlock *B) const { return Frontiers.find(B); } 937 938 void addBasicBlock(BasicBlock *BB, const DomSetType &frontier) { 939 assert(find(BB) == end() && "Block already in DominanceFrontier!"); 940 Frontiers.insert(std::make_pair(BB, frontier)); 941 } 942 943 /// removeBlock - Remove basic block BB's frontier. 944 void removeBlock(BasicBlock *BB) { 945 assert(find(BB) != end() && "Block is not in DominanceFrontier!"); 946 for (iterator I = begin(), E = end(); I != E; ++I) 947 I->second.erase(BB); 948 Frontiers.erase(BB); 949 } 950 951 void addToFrontier(iterator I, BasicBlock *Node) { 952 assert(I != end() && "BB is not in DominanceFrontier!"); 953 I->second.insert(Node); 954 } 955 956 void removeFromFrontier(iterator I, BasicBlock *Node) { 957 assert(I != end() && "BB is not in DominanceFrontier!"); 958 assert(I->second.count(Node) && "Node is not in DominanceFrontier of BB"); 959 I->second.erase(Node); 960 } 961 962 /// compareDomSet - Return false if two domsets match. Otherwise 963 /// return true; 964 bool compareDomSet(DomSetType &DS1, const DomSetType &DS2) const { 965 std::set<BasicBlock *> tmpSet; 966 for (DomSetType::const_iterator I = DS2.begin(), 967 E = DS2.end(); I != E; ++I) 968 tmpSet.insert(*I); 969 970 for (DomSetType::const_iterator I = DS1.begin(), 971 E = DS1.end(); I != E; ) { 972 BasicBlock *Node = *I++; 973 974 if (tmpSet.erase(Node) == 0) 975 // Node is in DS1 but not in DS2. 976 return true; 977 } 978 979 if(!tmpSet.empty()) 980 // There are nodes that are in DS2 but not in DS1. 981 return true; 982 983 // DS1 and DS2 matches. 984 return false; 985 } 986 987 /// compare - Return true if the other dominance frontier base matches 988 /// this dominance frontier base. Otherwise return false. 989 bool compare(DominanceFrontierBase &Other) const { 990 DomSetMapType tmpFrontiers; 991 for (DomSetMapType::const_iterator I = Other.begin(), 992 E = Other.end(); I != E; ++I) 993 tmpFrontiers.insert(std::make_pair(I->first, I->second)); 994 995 for (DomSetMapType::iterator I = tmpFrontiers.begin(), 996 E = tmpFrontiers.end(); I != E; ) { 997 BasicBlock *Node = I->first; 998 const_iterator DFI = find(Node); 999 if (DFI == end()) 1000 return true; 1001 1002 if (compareDomSet(I->second, DFI->second)) 1003 return true; 1004 1005 ++I; 1006 tmpFrontiers.erase(Node); 1007 } 1008 1009 if (!tmpFrontiers.empty()) 1010 return true; 1011 1012 return false; 1013 } 1014 1015 /// print - Convert to human readable form 1016 /// 1017 virtual void print(std::ostream &OS, const Module* = 0) const; 1018 void print(std::ostream *OS, const Module* M = 0) const { 1019 if (OS) print(*OS, M); 1020 } 1021 virtual void dump(); 1022}; 1023 1024 1025//===------------------------------------- 1026/// DominanceFrontier Class - Concrete subclass of DominanceFrontierBase that is 1027/// used to compute a forward dominator frontiers. 1028/// 1029class DominanceFrontier : public DominanceFrontierBase { 1030public: 1031 static char ID; // Pass ID, replacement for typeid 1032 DominanceFrontier() : 1033 DominanceFrontierBase(&ID, false) {} 1034 1035 BasicBlock *getRoot() const { 1036 assert(Roots.size() == 1 && "Should always have entry node!"); 1037 return Roots[0]; 1038 } 1039 1040 virtual bool runOnFunction(Function &) { 1041 Frontiers.clear(); 1042 DominatorTree &DT = getAnalysis<DominatorTree>(); 1043 Roots = DT.getRoots(); 1044 assert(Roots.size() == 1 && "Only one entry block for forward domfronts!"); 1045 calculate(DT, DT[Roots[0]]); 1046 return false; 1047 } 1048 1049 virtual void getAnalysisUsage(AnalysisUsage &AU) const { 1050 AU.setPreservesAll(); 1051 AU.addRequired<DominatorTree>(); 1052 } 1053 1054 /// splitBlock - BB is split and now it has one successor. Update dominance 1055 /// frontier to reflect this change. 1056 void splitBlock(BasicBlock *BB); 1057 1058 /// BasicBlock BB's new dominator is NewBB. Update BB's dominance frontier 1059 /// to reflect this change. 1060 void changeImmediateDominator(BasicBlock *BB, BasicBlock *NewBB, 1061 DominatorTree *DT) { 1062 // NewBB is now dominating BB. Which means BB's dominance 1063 // frontier is now part of NewBB's dominance frontier. However, BB 1064 // itself is not member of NewBB's dominance frontier. 1065 DominanceFrontier::iterator NewDFI = find(NewBB); 1066 DominanceFrontier::iterator DFI = find(BB); 1067 // If BB was an entry block then its frontier is empty. 1068 if (DFI == end()) 1069 return; 1070 DominanceFrontier::DomSetType BBSet = DFI->second; 1071 for (DominanceFrontier::DomSetType::iterator BBSetI = BBSet.begin(), 1072 BBSetE = BBSet.end(); BBSetI != BBSetE; ++BBSetI) { 1073 BasicBlock *DFMember = *BBSetI; 1074 // Insert only if NewBB dominates DFMember. 1075 if (!DT->dominates(NewBB, DFMember)) 1076 NewDFI->second.insert(DFMember); 1077 } 1078 NewDFI->second.erase(BB); 1079 } 1080 1081 const DomSetType &calculate(const DominatorTree &DT, 1082 const DomTreeNode *Node); 1083}; 1084 1085 1086} // End llvm namespace 1087 1088#endif 1089