Dominators.h revision 34cd4a484e532cc463fd5a4bf59b88d13c5467c1
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/Instruction.h" 28#include "llvm/Instructions.h" 29#include "llvm/ADT/DenseMap.h" 30#include "llvm/ADT/GraphTraits.h" 31#include "llvm/ADT/SmallPtrSet.h" 32#include "llvm/ADT/SmallVector.h" 33#include "llvm/Assembly/Writer.h" 34#include "llvm/Support/CFG.h" 35#include "llvm/Support/Compiler.h" 36#include <algorithm> 37#include <map> 38#include <set> 39 40namespace llvm { 41 42//===----------------------------------------------------------------------===// 43/// DominatorBase - Base class that other, more interesting dominator analyses 44/// inherit from. 45/// 46template <class NodeT> 47class DominatorBase { 48protected: 49 std::vector<NodeT*> Roots; 50 const bool IsPostDominators; 51 inline explicit DominatorBase(bool isPostDom) : 52 Roots(), IsPostDominators(isPostDom) {} 53public: 54 55 /// getRoots - Return the root blocks of the current CFG. This may include 56 /// multiple blocks if we are computing post dominators. For forward 57 /// dominators, this will always be a single block (the entry node). 58 /// 59 inline const std::vector<NodeT*> &getRoots() const { return Roots; } 60 61 /// isPostDominator - Returns true if analysis based of postdoms 62 /// 63 bool isPostDominator() const { return IsPostDominators; } 64}; 65 66 67//===----------------------------------------------------------------------===// 68// DomTreeNode - Dominator Tree Node 69template<class NodeT> class DominatorTreeBase; 70struct PostDominatorTree; 71class MachineBasicBlock; 72 73template <class NodeT> 74class DomTreeNodeBase { 75 NodeT *TheBB; 76 DomTreeNodeBase<NodeT> *IDom; 77 std::vector<DomTreeNodeBase<NodeT> *> Children; 78 int DFSNumIn, DFSNumOut; 79 80 template<class N> friend class DominatorTreeBase; 81 friend struct PostDominatorTree; 82public: 83 typedef typename std::vector<DomTreeNodeBase<NodeT> *>::iterator iterator; 84 typedef typename std::vector<DomTreeNodeBase<NodeT> *>::const_iterator 85 const_iterator; 86 87 iterator begin() { return Children.begin(); } 88 iterator end() { return Children.end(); } 89 const_iterator begin() const { return Children.begin(); } 90 const_iterator end() const { return Children.end(); } 91 92 NodeT *getBlock() const { return TheBB; } 93 DomTreeNodeBase<NodeT> *getIDom() const { return IDom; } 94 const std::vector<DomTreeNodeBase<NodeT>*> &getChildren() const { 95 return Children; 96 } 97 98 DomTreeNodeBase(NodeT *BB, DomTreeNodeBase<NodeT> *iDom) 99 : TheBB(BB), IDom(iDom), DFSNumIn(-1), DFSNumOut(-1) { } 100 101 DomTreeNodeBase<NodeT> *addChild(DomTreeNodeBase<NodeT> *C) { 102 Children.push_back(C); 103 return C; 104 } 105 106 size_t getNumChildren() const { 107 return Children.size(); 108 } 109 110 void setIDom(DomTreeNodeBase<NodeT> *NewIDom) { 111 assert(IDom && "No immediate dominator?"); 112 if (IDom != NewIDom) { 113 typename std::vector<DomTreeNodeBase<NodeT>*>::iterator I = 114 std::find(IDom->Children.begin(), IDom->Children.end(), this); 115 assert(I != IDom->Children.end() && 116 "Not in immediate dominator children set!"); 117 // I am no longer your child... 118 IDom->Children.erase(I); 119 120 // Switch to new dominator 121 IDom = NewIDom; 122 IDom->Children.push_back(this); 123 } 124 } 125 126 /// getDFSNumIn/getDFSNumOut - These are an internal implementation detail, do 127 /// not call them. 128 unsigned getDFSNumIn() const { return DFSNumIn; } 129 unsigned getDFSNumOut() const { return DFSNumOut; } 130private: 131 // Return true if this node is dominated by other. Use this only if DFS info 132 // is valid. 133 bool DominatedBy(const DomTreeNodeBase<NodeT> *other) const { 134 return this->DFSNumIn >= other->DFSNumIn && 135 this->DFSNumOut <= other->DFSNumOut; 136 } 137}; 138 139EXTERN_TEMPLATE_INSTANTIATION(class DomTreeNodeBase<BasicBlock>); 140EXTERN_TEMPLATE_INSTANTIATION(class DomTreeNodeBase<MachineBasicBlock>); 141 142template<class NodeT> 143static std::ostream &operator<<(std::ostream &o, 144 const DomTreeNodeBase<NodeT> *Node) { 145 if (Node->getBlock()) 146 WriteAsOperand(o, Node->getBlock(), false); 147 else 148 o << " <<exit node>>"; 149 150 o << " {" << Node->getDFSNumIn() << "," << Node->getDFSNumOut() << "}"; 151 152 return o << "\n"; 153} 154 155template<class NodeT> 156static void PrintDomTree(const DomTreeNodeBase<NodeT> *N, std::ostream &o, 157 unsigned Lev) { 158 o << std::string(2*Lev, ' ') << "[" << Lev << "] " << N; 159 for (typename DomTreeNodeBase<NodeT>::const_iterator I = N->begin(), 160 E = N->end(); I != E; ++I) 161 PrintDomTree<NodeT>(*I, o, Lev+1); 162} 163 164typedef DomTreeNodeBase<BasicBlock> DomTreeNode; 165 166//===----------------------------------------------------------------------===// 167/// DominatorTree - Calculate the immediate dominator tree for a function. 168/// 169 170template<class FuncT, class N> 171void Calculate(DominatorTreeBase<typename GraphTraits<N>::NodeType>& DT, 172 FuncT& F); 173 174template<class NodeT> 175class DominatorTreeBase : public DominatorBase<NodeT> { 176protected: 177 typedef DenseMap<NodeT*, DomTreeNodeBase<NodeT>*> DomTreeNodeMapType; 178 DomTreeNodeMapType DomTreeNodes; 179 DomTreeNodeBase<NodeT> *RootNode; 180 181 bool DFSInfoValid; 182 unsigned int SlowQueries; 183 // Information record used during immediate dominators computation. 184 struct InfoRec { 185 unsigned DFSNum; 186 unsigned Semi; 187 unsigned Size; 188 NodeT *Label, *Child; 189 unsigned Parent, Ancestor; 190 191 std::vector<NodeT*> Bucket; 192 193 InfoRec() : DFSNum(0), Semi(0), Size(0), Label(0), Child(0), Parent(0), 194 Ancestor(0) {} 195 }; 196 197 DenseMap<NodeT*, NodeT*> IDoms; 198 199 // Vertex - Map the DFS number to the BasicBlock* 200 std::vector<NodeT*> Vertex; 201 202 // Info - Collection of information used during the computation of idoms. 203 DenseMap<NodeT*, InfoRec> Info; 204 205 void reset() { 206 for (typename DomTreeNodeMapType::iterator I = this->DomTreeNodes.begin(), 207 E = DomTreeNodes.end(); I != E; ++I) 208 delete I->second; 209 DomTreeNodes.clear(); 210 IDoms.clear(); 211 this->Roots.clear(); 212 Vertex.clear(); 213 RootNode = 0; 214 } 215 216 // NewBB is split and now it has one successor. Update dominator tree to 217 // reflect this change. 218 template<class N, class GraphT> 219 void Split(DominatorTreeBase<typename GraphT::NodeType>& DT, 220 typename GraphT::NodeType* NewBB) { 221 assert(std::distance(GraphT::child_begin(NewBB), GraphT::child_end(NewBB)) == 1 222 && "NewBB should have a single successor!"); 223 typename GraphT::NodeType* NewBBSucc = *GraphT::child_begin(NewBB); 224 225 std::vector<typename GraphT::NodeType*> PredBlocks; 226 for (typename GraphTraits<Inverse<N> >::ChildIteratorType PI = 227 GraphTraits<Inverse<N> >::child_begin(NewBB), 228 PE = GraphTraits<Inverse<N> >::child_end(NewBB); PI != PE; ++PI) 229 PredBlocks.push_back(*PI); 230 231 assert(!PredBlocks.empty() && "No predblocks??"); 232 233 // The newly inserted basic block will dominate existing basic blocks iff the 234 // PredBlocks dominate all of the non-pred blocks. If all predblocks dominate 235 // the non-pred blocks, then they all must be the same block! 236 // 237 bool NewBBDominatesNewBBSucc = true; 238 { 239 typename GraphT::NodeType* OnePred = PredBlocks[0]; 240 size_t i = 1, e = PredBlocks.size(); 241 for (i = 1; !DT.isReachableFromEntry(OnePred); ++i) { 242 assert(i != e && "Didn't find reachable pred?"); 243 OnePred = PredBlocks[i]; 244 } 245 246 for (; i != e; ++i) 247 if (PredBlocks[i] != OnePred && DT.isReachableFromEntry(OnePred)) { 248 NewBBDominatesNewBBSucc = false; 249 break; 250 } 251 252 if (NewBBDominatesNewBBSucc) 253 for (typename GraphTraits<Inverse<N> >::ChildIteratorType PI = 254 GraphTraits<Inverse<N> >::child_begin(NewBBSucc), 255 E = GraphTraits<Inverse<N> >::child_end(NewBBSucc); PI != E; ++PI) 256 if (*PI != NewBB && !DT.dominates(NewBBSucc, *PI)) { 257 NewBBDominatesNewBBSucc = false; 258 break; 259 } 260 } 261 262 // The other scenario where the new block can dominate its successors are when 263 // all predecessors of NewBBSucc that are not NewBB are dominated by NewBBSucc 264 // already. 265 if (!NewBBDominatesNewBBSucc) { 266 NewBBDominatesNewBBSucc = true; 267 for (typename GraphTraits<Inverse<N> >::ChildIteratorType PI = 268 GraphTraits<Inverse<N> >::child_begin(NewBBSucc), 269 E = GraphTraits<Inverse<N> >::child_end(NewBBSucc); PI != E; ++PI) 270 if (*PI != NewBB && !DT.dominates(NewBBSucc, *PI)) { 271 NewBBDominatesNewBBSucc = false; 272 break; 273 } 274 } 275 276 // Find NewBB's immediate dominator and create new dominator tree node for 277 // NewBB. 278 NodeT *NewBBIDom = 0; 279 unsigned i = 0; 280 for (i = 0; i < PredBlocks.size(); ++i) 281 if (DT.isReachableFromEntry(PredBlocks[i])) { 282 NewBBIDom = PredBlocks[i]; 283 break; 284 } 285 assert(i != PredBlocks.size() && "No reachable preds?"); 286 for (i = i + 1; i < PredBlocks.size(); ++i) { 287 if (DT.isReachableFromEntry(PredBlocks[i])) 288 NewBBIDom = DT.findNearestCommonDominator(NewBBIDom, PredBlocks[i]); 289 } 290 assert(NewBBIDom && "No immediate dominator found??"); 291 292 // Create the new dominator tree node... and set the idom of NewBB. 293 DomTreeNodeBase<NodeT> *NewBBNode = DT.addNewBlock(NewBB, NewBBIDom); 294 295 // If NewBB strictly dominates other blocks, then it is now the immediate 296 // dominator of NewBBSucc. Update the dominator tree as appropriate. 297 if (NewBBDominatesNewBBSucc) { 298 DomTreeNodeBase<NodeT> *NewBBSuccNode = DT.getNode(NewBBSucc); 299 DT.changeImmediateDominator(NewBBSuccNode, NewBBNode); 300 } 301 } 302 303public: 304 explicit DominatorTreeBase(bool isPostDom) 305 : DominatorBase<NodeT>(isPostDom), DFSInfoValid(false), SlowQueries(0) {} 306 virtual ~DominatorTreeBase() { reset(); } 307 308 // FIXME: Should remove this 309 virtual bool runOnFunction(Function &F) { return false; } 310 311 virtual void releaseMemory() { reset(); } 312 313 /// getNode - return the (Post)DominatorTree node for the specified basic 314 /// block. This is the same as using operator[] on this class. 315 /// 316 inline DomTreeNodeBase<NodeT> *getNode(NodeT *BB) const { 317 typename DomTreeNodeMapType::const_iterator I = DomTreeNodes.find(BB); 318 return I != DomTreeNodes.end() ? I->second : 0; 319 } 320 321 /// getRootNode - This returns the entry node for the CFG of the function. If 322 /// this tree represents the post-dominance relations for a function, however, 323 /// this root may be a node with the block == NULL. This is the case when 324 /// there are multiple exit nodes from a particular function. Consumers of 325 /// post-dominance information must be capable of dealing with this 326 /// possibility. 327 /// 328 DomTreeNodeBase<NodeT> *getRootNode() { return RootNode; } 329 const DomTreeNodeBase<NodeT> *getRootNode() const { return RootNode; } 330 331 /// properlyDominates - Returns true iff this dominates N and this != N. 332 /// Note that this is not a constant time operation! 333 /// 334 bool properlyDominates(const DomTreeNodeBase<NodeT> *A, 335 DomTreeNodeBase<NodeT> *B) const { 336 if (A == 0 || B == 0) return false; 337 return dominatedBySlowTreeWalk(A, B); 338 } 339 340 inline bool properlyDominates(NodeT *A, NodeT *B) { 341 return properlyDominates(getNode(A), getNode(B)); 342 } 343 344 bool dominatedBySlowTreeWalk(const DomTreeNodeBase<NodeT> *A, 345 const DomTreeNodeBase<NodeT> *B) const { 346 const DomTreeNodeBase<NodeT> *IDom; 347 if (A == 0 || B == 0) return false; 348 while ((IDom = B->getIDom()) != 0 && IDom != A && IDom != B) 349 B = IDom; // Walk up the tree 350 return IDom != 0; 351 } 352 353 354 /// isReachableFromEntry - Return true if A is dominated by the entry 355 /// block of the function containing it. 356 bool isReachableFromEntry(NodeT* A) { 357 assert (!this->isPostDominator() 358 && "This is not implemented for post dominators"); 359 return dominates(&A->getParent()->front(), A); 360 } 361 362 /// dominates - Returns true iff A dominates B. Note that this is not a 363 /// constant time operation! 364 /// 365 inline bool dominates(const DomTreeNodeBase<NodeT> *A, 366 DomTreeNodeBase<NodeT> *B) { 367 if (B == A) 368 return true; // A node trivially dominates itself. 369 370 if (A == 0 || B == 0) 371 return false; 372 373 if (DFSInfoValid) 374 return B->DominatedBy(A); 375 376 // If we end up with too many slow queries, just update the 377 // DFS numbers on the theory that we are going to keep querying. 378 SlowQueries++; 379 if (SlowQueries > 32) { 380 updateDFSNumbers(); 381 return B->DominatedBy(A); 382 } 383 384 return dominatedBySlowTreeWalk(A, B); 385 } 386 387 inline bool dominates(NodeT *A, NodeT *B) { 388 if (A == B) 389 return true; 390 391 return dominates(getNode(A), getNode(B)); 392 } 393 394 NodeT *getRoot() const { 395 assert(this->Roots.size() == 1 && "Should always have entry node!"); 396 return this->Roots[0]; 397 } 398 399 /// findNearestCommonDominator - Find nearest common dominator basic block 400 /// for basic block A and B. If there is no such block then return NULL. 401 NodeT *findNearestCommonDominator(NodeT *A, NodeT *B) { 402 403 assert (!this->isPostDominator() 404 && "This is not implemented for post dominators"); 405 assert (A->getParent() == B->getParent() 406 && "Two blocks are not in same function"); 407 408 // If either A or B is a entry block then it is nearest common dominator. 409 NodeT &Entry = A->getParent()->front(); 410 if (A == &Entry || B == &Entry) 411 return &Entry; 412 413 // If B dominates A then B is nearest common dominator. 414 if (dominates(B, A)) 415 return B; 416 417 // If A dominates B then A is nearest common dominator. 418 if (dominates(A, B)) 419 return A; 420 421 DomTreeNodeBase<NodeT> *NodeA = getNode(A); 422 DomTreeNodeBase<NodeT> *NodeB = getNode(B); 423 424 // Collect NodeA dominators set. 425 SmallPtrSet<DomTreeNodeBase<NodeT>*, 16> NodeADoms; 426 NodeADoms.insert(NodeA); 427 DomTreeNodeBase<NodeT> *IDomA = NodeA->getIDom(); 428 while (IDomA) { 429 NodeADoms.insert(IDomA); 430 IDomA = IDomA->getIDom(); 431 } 432 433 // Walk NodeB immediate dominators chain and find common dominator node. 434 DomTreeNodeBase<NodeT> *IDomB = NodeB->getIDom(); 435 while(IDomB) { 436 if (NodeADoms.count(IDomB) != 0) 437 return IDomB->getBlock(); 438 439 IDomB = IDomB->getIDom(); 440 } 441 442 return NULL; 443 } 444 445 //===--------------------------------------------------------------------===// 446 // API to update (Post)DominatorTree information based on modifications to 447 // the CFG... 448 449 /// addNewBlock - Add a new node to the dominator tree information. This 450 /// creates a new node as a child of DomBB dominator node,linking it into 451 /// the children list of the immediate dominator. 452 DomTreeNodeBase<NodeT> *addNewBlock(NodeT *BB, NodeT *DomBB) { 453 assert(getNode(BB) == 0 && "Block already in dominator tree!"); 454 DomTreeNodeBase<NodeT> *IDomNode = getNode(DomBB); 455 assert(IDomNode && "Not immediate dominator specified for block!"); 456 DFSInfoValid = false; 457 return DomTreeNodes[BB] = 458 IDomNode->addChild(new DomTreeNodeBase<NodeT>(BB, IDomNode)); 459 } 460 461 /// changeImmediateDominator - This method is used to update the dominator 462 /// tree information when a node's immediate dominator changes. 463 /// 464 void changeImmediateDominator(DomTreeNodeBase<NodeT> *N, 465 DomTreeNodeBase<NodeT> *NewIDom) { 466 assert(N && NewIDom && "Cannot change null node pointers!"); 467 DFSInfoValid = false; 468 N->setIDom(NewIDom); 469 } 470 471 void changeImmediateDominator(NodeT *BB, NodeT *NewBB) { 472 changeImmediateDominator(getNode(BB), getNode(NewBB)); 473 } 474 475 /// eraseNode - Removes a node from the dominator tree. Block must not 476 /// domiante any other blocks. Removes node from its immediate dominator's 477 /// children list. Deletes dominator node associated with basic block BB. 478 void eraseNode(NodeT *BB) { 479 DomTreeNodeBase<NodeT> *Node = getNode(BB); 480 assert (Node && "Removing node that isn't in dominator tree."); 481 assert (Node->getChildren().empty() && "Node is not a leaf node."); 482 483 // Remove node from immediate dominator's children list. 484 DomTreeNodeBase<NodeT> *IDom = Node->getIDom(); 485 if (IDom) { 486 typename std::vector<DomTreeNodeBase<NodeT>*>::iterator I = 487 std::find(IDom->Children.begin(), IDom->Children.end(), Node); 488 assert(I != IDom->Children.end() && 489 "Not in immediate dominator children set!"); 490 // I am no longer your child... 491 IDom->Children.erase(I); 492 } 493 494 DomTreeNodes.erase(BB); 495 delete Node; 496 } 497 498 /// removeNode - Removes a node from the dominator tree. Block must not 499 /// dominate any other blocks. Invalidates any node pointing to removed 500 /// block. 501 void removeNode(NodeT *BB) { 502 assert(getNode(BB) && "Removing node that isn't in dominator tree."); 503 DomTreeNodes.erase(BB); 504 } 505 506 /// splitBlock - BB is split and now it has one successor. Update dominator 507 /// tree to reflect this change. 508 void splitBlock(NodeT* NewBB) { 509 if (this->IsPostDominators) 510 this->Split<Inverse<NodeT*>, GraphTraits<Inverse<NodeT*> > >(*this, NewBB); 511 else 512 this->Split<NodeT*, GraphTraits<NodeT*> >(*this, NewBB); 513 } 514 515 /// print - Convert to human readable form 516 /// 517 virtual void print(std::ostream &o, const Module* ) const { 518 o << "=============================--------------------------------\n"; 519 if (this->isPostDominator()) 520 o << "Inorder PostDominator Tree: "; 521 else 522 o << "Inorder Dominator Tree: "; 523 if (this->DFSInfoValid) 524 o << "DFSNumbers invalid: " << SlowQueries << " slow queries."; 525 o << "\n"; 526 527 PrintDomTree<NodeT>(getRootNode(), o, 1); 528 } 529 530 void print(std::ostream *OS, const Module* M = 0) const { 531 if (OS) print(*OS, M); 532 } 533 534 virtual void dump() { 535 print(llvm::cerr); 536 } 537 538protected: 539 template<class GraphT> 540 friend void Compress(DominatorTreeBase<typename GraphT::NodeType>& DT, 541 typename GraphT::NodeType* VIn); 542 543 template<class GraphT> 544 friend typename GraphT::NodeType* Eval( 545 DominatorTreeBase<typename GraphT::NodeType>& DT, 546 typename GraphT::NodeType* V); 547 548 template<class GraphT> 549 friend void Link(DominatorTreeBase<typename GraphT::NodeType>& DT, 550 unsigned DFSNumV, typename GraphT::NodeType* W, 551 typename DominatorTreeBase<typename GraphT::NodeType>::InfoRec &WInfo); 552 553 template<class GraphT> 554 friend unsigned DFSPass(DominatorTreeBase<typename GraphT::NodeType>& DT, 555 typename GraphT::NodeType* V, 556 unsigned N); 557 558 template<class FuncT, class N> 559 friend void Calculate(DominatorTreeBase<typename GraphTraits<N>::NodeType>& DT, 560 FuncT& F); 561 562 /// updateDFSNumbers - Assign In and Out numbers to the nodes while walking 563 /// dominator tree in dfs order. 564 void updateDFSNumbers() { 565 unsigned DFSNum = 0; 566 567 SmallVector<std::pair<DomTreeNodeBase<NodeT>*, 568 typename DomTreeNodeBase<NodeT>::iterator>, 32> WorkStack; 569 570 for (unsigned i = 0, e = (unsigned)this->Roots.size(); i != e; ++i) { 571 DomTreeNodeBase<NodeT> *ThisRoot = getNode(this->Roots[i]); 572 WorkStack.push_back(std::make_pair(ThisRoot, ThisRoot->begin())); 573 ThisRoot->DFSNumIn = DFSNum++; 574 575 while (!WorkStack.empty()) { 576 DomTreeNodeBase<NodeT> *Node = WorkStack.back().first; 577 typename DomTreeNodeBase<NodeT>::iterator ChildIt = 578 WorkStack.back().second; 579 580 // If we visited all of the children of this node, "recurse" back up the 581 // stack setting the DFOutNum. 582 if (ChildIt == Node->end()) { 583 Node->DFSNumOut = DFSNum++; 584 WorkStack.pop_back(); 585 } else { 586 // Otherwise, recursively visit this child. 587 DomTreeNodeBase<NodeT> *Child = *ChildIt; 588 ++WorkStack.back().second; 589 590 WorkStack.push_back(std::make_pair(Child, Child->begin())); 591 Child->DFSNumIn = DFSNum++; 592 } 593 } 594 } 595 596 SlowQueries = 0; 597 DFSInfoValid = true; 598 } 599 600 DomTreeNodeBase<NodeT> *getNodeForBlock(NodeT *BB) { 601 if (DomTreeNodeBase<NodeT> *BBNode = this->DomTreeNodes[BB]) 602 return BBNode; 603 604 // Haven't calculated this node yet? Get or calculate the node for the 605 // immediate dominator. 606 NodeT *IDom = getIDom(BB); 607 608 assert(IDom || this->DomTreeNodes[NULL]); 609 DomTreeNodeBase<NodeT> *IDomNode = getNodeForBlock(IDom); 610 611 // Add a new tree node for this BasicBlock, and link it as a child of 612 // IDomNode 613 DomTreeNodeBase<NodeT> *C = new DomTreeNodeBase<NodeT>(BB, IDomNode); 614 return this->DomTreeNodes[BB] = IDomNode->addChild(C); 615 } 616 617 inline NodeT *getIDom(NodeT *BB) const { 618 typename DenseMap<NodeT*, NodeT*>::const_iterator I = IDoms.find(BB); 619 return I != IDoms.end() ? I->second : 0; 620 } 621 622 inline void addRoot(NodeT* BB) { 623 this->Roots.push_back(BB); 624 } 625 626public: 627 /// recalculate - compute a dominator tree for the given function 628 template<class FT> 629 void recalculate(FT& F) { 630 if (!this->IsPostDominators) { 631 reset(); 632 633 // Initialize roots 634 this->Roots.push_back(&F.front()); 635 this->IDoms[&F.front()] = 0; 636 this->DomTreeNodes[&F.front()] = 0; 637 this->Vertex.push_back(0); 638 639 Calculate<FT, NodeT*>(*this, F); 640 641 updateDFSNumbers(); 642 } else { 643 reset(); // Reset from the last time we were run... 644 645 // Initialize the roots list 646 for (typename FT::iterator I = F.begin(), E = F.end(); I != E; ++I) { 647 if (std::distance(GraphTraits<FT*>::child_begin(I), 648 GraphTraits<FT*>::child_end(I)) == 0) 649 addRoot(I); 650 651 // Prepopulate maps so that we don't get iterator invalidation issues later. 652 this->IDoms[I] = 0; 653 this->DomTreeNodes[I] = 0; 654 } 655 656 this->Vertex.push_back(0); 657 658 Calculate<FT, Inverse<NodeT*> >(*this, F); 659 } 660 } 661}; 662 663EXTERN_TEMPLATE_INSTANTIATION(class DominatorTreeBase<BasicBlock>); 664 665//===------------------------------------- 666/// DominatorTree Class - Concrete subclass of DominatorTreeBase that is used to 667/// compute a normal dominator tree. 668/// 669class DominatorTree : public FunctionPass { 670public: 671 static char ID; // Pass ID, replacement for typeid 672 DominatorTreeBase<BasicBlock>* DT; 673 674 DominatorTree() : FunctionPass(intptr_t(&ID)) { 675 DT = new DominatorTreeBase<BasicBlock>(false); 676 } 677 678 ~DominatorTree() { 679 DT->releaseMemory(); 680 delete DT; 681 } 682 683 DominatorTreeBase<BasicBlock>& getBase() { return *DT; } 684 685 /// getRoots - Return the root blocks of the current CFG. This may include 686 /// multiple blocks if we are computing post dominators. For forward 687 /// dominators, this will always be a single block (the entry node). 688 /// 689 inline const std::vector<BasicBlock*> &getRoots() const { 690 return DT->getRoots(); 691 } 692 693 inline BasicBlock *getRoot() const { 694 return DT->getRoot(); 695 } 696 697 inline DomTreeNode *getRootNode() const { 698 return DT->getRootNode(); 699 } 700 701 virtual bool runOnFunction(Function &F); 702 703 virtual void getAnalysisUsage(AnalysisUsage &AU) const { 704 AU.setPreservesAll(); 705 } 706 707 inline bool dominates(DomTreeNode* A, DomTreeNode* B) const { 708 return DT->dominates(A, B); 709 } 710 711 inline bool dominates(BasicBlock* A, BasicBlock* B) const { 712 return DT->dominates(A, B); 713 } 714 715 // dominates - Return true if A dominates B. This performs the 716 // special checks necessary if A and B are in the same basic block. 717 bool dominates(Instruction *A, Instruction *B) const { 718 BasicBlock *BBA = A->getParent(), *BBB = B->getParent(); 719 if (BBA != BBB) return DT->dominates(BBA, BBB); 720 721 // It is not possible to determine dominance between two PHI nodes 722 // based on their ordering. 723 if (isa<PHINode>(A) && isa<PHINode>(B)) 724 return false; 725 726 // Loop through the basic block until we find A or B. 727 BasicBlock::iterator I = BBA->begin(); 728 for (; &*I != A && &*I != B; ++I) /*empty*/; 729 730 //if(!DT.IsPostDominators) { 731 // A dominates B if it is found first in the basic block. 732 return &*I == A; 733 //} else { 734 // // A post-dominates B if B is found first in the basic block. 735 // return &*I == B; 736 //} 737 } 738 739 inline bool properlyDominates(const DomTreeNode* A, DomTreeNode* B) const { 740 return DT->properlyDominates(A, B); 741 } 742 743 inline bool properlyDominates(BasicBlock* A, BasicBlock* B) const { 744 return DT->properlyDominates(A, B); 745 } 746 747 /// findNearestCommonDominator - Find nearest common dominator basic block 748 /// for basic block A and B. If there is no such block then return NULL. 749 inline BasicBlock *findNearestCommonDominator(BasicBlock *A, BasicBlock *B) { 750 return DT->findNearestCommonDominator(A, B); 751 } 752 753 inline DomTreeNode *operator[](BasicBlock *BB) const { 754 return DT->getNode(BB); 755 } 756 757 /// getNode - return the (Post)DominatorTree node for the specified basic 758 /// block. This is the same as using operator[] on this class. 759 /// 760 inline DomTreeNode *getNode(BasicBlock *BB) const { 761 return DT->getNode(BB); 762 } 763 764 /// addNewBlock - Add a new node to the dominator tree information. This 765 /// creates a new node as a child of DomBB dominator node,linking it into 766 /// the children list of the immediate dominator. 767 inline DomTreeNode *addNewBlock(BasicBlock *BB, BasicBlock *DomBB) { 768 return DT->addNewBlock(BB, DomBB); 769 } 770 771 /// changeImmediateDominator - This method is used to update the dominator 772 /// tree information when a node's immediate dominator changes. 773 /// 774 inline void changeImmediateDominator(BasicBlock *N, BasicBlock* NewIDom) { 775 DT->changeImmediateDominator(N, NewIDom); 776 } 777 778 inline void changeImmediateDominator(DomTreeNode *N, DomTreeNode* NewIDom) { 779 DT->changeImmediateDominator(N, NewIDom); 780 } 781 782 /// eraseNode - Removes a node from the dominator tree. Block must not 783 /// domiante any other blocks. Removes node from its immediate dominator's 784 /// children list. Deletes dominator node associated with basic block BB. 785 inline void eraseNode(BasicBlock *BB) { 786 DT->eraseNode(BB); 787 } 788 789 /// splitBlock - BB is split and now it has one successor. Update dominator 790 /// tree to reflect this change. 791 inline void splitBlock(BasicBlock* NewBB) { 792 DT->splitBlock(NewBB); 793 } 794 795 796 virtual void releaseMemory() { 797 DT->releaseMemory(); 798 } 799 800 virtual void print(std::ostream &OS, const Module* M= 0) const { 801 DT->print(OS, M); 802 } 803}; 804 805//===------------------------------------- 806/// DominatorTree GraphTraits specialization so the DominatorTree can be 807/// iterable by generic graph iterators. 808/// 809template <> struct GraphTraits<DomTreeNode *> { 810 typedef DomTreeNode NodeType; 811 typedef NodeType::iterator ChildIteratorType; 812 813 static NodeType *getEntryNode(NodeType *N) { 814 return N; 815 } 816 static inline ChildIteratorType child_begin(NodeType* N) { 817 return N->begin(); 818 } 819 static inline ChildIteratorType child_end(NodeType* N) { 820 return N->end(); 821 } 822}; 823 824template <> struct GraphTraits<DominatorTree*> 825 : public GraphTraits<DomTreeNode *> { 826 static NodeType *getEntryNode(DominatorTree *DT) { 827 return DT->getRootNode(); 828 } 829}; 830 831 832//===----------------------------------------------------------------------===// 833/// DominanceFrontierBase - Common base class for computing forward and inverse 834/// dominance frontiers for a function. 835/// 836class DominanceFrontierBase : public FunctionPass { 837public: 838 typedef std::set<BasicBlock*> DomSetType; // Dom set for a bb 839 typedef std::map<BasicBlock*, DomSetType> DomSetMapType; // Dom set map 840protected: 841 DomSetMapType Frontiers; 842 std::vector<BasicBlock*> Roots; 843 const bool IsPostDominators; 844 845public: 846 DominanceFrontierBase(intptr_t ID, bool isPostDom) 847 : FunctionPass(ID), IsPostDominators(isPostDom) {} 848 849 /// getRoots - Return the root blocks of the current CFG. This may include 850 /// multiple blocks if we are computing post dominators. For forward 851 /// dominators, this will always be a single block (the entry node). 852 /// 853 inline const std::vector<BasicBlock*> &getRoots() const { return Roots; } 854 855 /// isPostDominator - Returns true if analysis based of postdoms 856 /// 857 bool isPostDominator() const { return IsPostDominators; } 858 859 virtual void releaseMemory() { Frontiers.clear(); } 860 861 // Accessor interface: 862 typedef DomSetMapType::iterator iterator; 863 typedef DomSetMapType::const_iterator const_iterator; 864 iterator begin() { return Frontiers.begin(); } 865 const_iterator begin() const { return Frontiers.begin(); } 866 iterator end() { return Frontiers.end(); } 867 const_iterator end() const { return Frontiers.end(); } 868 iterator find(BasicBlock *B) { return Frontiers.find(B); } 869 const_iterator find(BasicBlock *B) const { return Frontiers.find(B); } 870 871 void addBasicBlock(BasicBlock *BB, const DomSetType &frontier) { 872 assert(find(BB) == end() && "Block already in DominanceFrontier!"); 873 Frontiers.insert(std::make_pair(BB, frontier)); 874 } 875 876 /// removeBlock - Remove basic block BB's frontier. 877 void removeBlock(BasicBlock *BB) { 878 assert(find(BB) != end() && "Block is not in DominanceFrontier!"); 879 for (iterator I = begin(), E = end(); I != E; ++I) 880 I->second.erase(BB); 881 Frontiers.erase(BB); 882 } 883 884 void addToFrontier(iterator I, BasicBlock *Node) { 885 assert(I != end() && "BB is not in DominanceFrontier!"); 886 I->second.insert(Node); 887 } 888 889 void removeFromFrontier(iterator I, BasicBlock *Node) { 890 assert(I != end() && "BB is not in DominanceFrontier!"); 891 assert(I->second.count(Node) && "Node is not in DominanceFrontier of BB"); 892 I->second.erase(Node); 893 } 894 895 /// print - Convert to human readable form 896 /// 897 virtual void print(std::ostream &OS, const Module* = 0) const; 898 void print(std::ostream *OS, const Module* M = 0) const { 899 if (OS) print(*OS, M); 900 } 901 virtual void dump(); 902}; 903 904 905//===------------------------------------- 906/// DominanceFrontier Class - Concrete subclass of DominanceFrontierBase that is 907/// used to compute a forward dominator frontiers. 908/// 909class DominanceFrontier : public DominanceFrontierBase { 910public: 911 static char ID; // Pass ID, replacement for typeid 912 DominanceFrontier() : 913 DominanceFrontierBase(intptr_t(&ID), false) {} 914 915 BasicBlock *getRoot() const { 916 assert(Roots.size() == 1 && "Should always have entry node!"); 917 return Roots[0]; 918 } 919 920 virtual bool runOnFunction(Function &) { 921 Frontiers.clear(); 922 DominatorTree &DT = getAnalysis<DominatorTree>(); 923 Roots = DT.getRoots(); 924 assert(Roots.size() == 1 && "Only one entry block for forward domfronts!"); 925 calculate(DT, DT[Roots[0]]); 926 return false; 927 } 928 929 virtual void getAnalysisUsage(AnalysisUsage &AU) const { 930 AU.setPreservesAll(); 931 AU.addRequired<DominatorTree>(); 932 } 933 934 /// splitBlock - BB is split and now it has one successor. Update dominance 935 /// frontier to reflect this change. 936 void splitBlock(BasicBlock *BB); 937 938 /// BasicBlock BB's new dominator is NewBB. Update BB's dominance frontier 939 /// to reflect this change. 940 void changeImmediateDominator(BasicBlock *BB, BasicBlock *NewBB, 941 DominatorTree *DT) { 942 // NewBB is now dominating BB. Which means BB's dominance 943 // frontier is now part of NewBB's dominance frontier. However, BB 944 // itself is not member of NewBB's dominance frontier. 945 DominanceFrontier::iterator NewDFI = find(NewBB); 946 DominanceFrontier::iterator DFI = find(BB); 947 DominanceFrontier::DomSetType BBSet = DFI->second; 948 for (DominanceFrontier::DomSetType::iterator BBSetI = BBSet.begin(), 949 BBSetE = BBSet.end(); BBSetI != BBSetE; ++BBSetI) { 950 BasicBlock *DFMember = *BBSetI; 951 // Insert only if NewBB dominates DFMember. 952 if (!DT->dominates(NewBB, DFMember)) 953 NewDFI->second.insert(DFMember); 954 } 955 NewDFI->second.erase(BB); 956 } 957 958private: 959 const DomSetType &calculate(const DominatorTree &DT, 960 const DomTreeNode *Node); 961}; 962 963 964} // End llvm namespace 965 966#endif 967