Dominators.h revision 950a4c40b823cd4f09dc71be635229246dfd6cac
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 void setIDom(DomTreeNodeBase<NodeT> *NewIDom) { 107 assert(IDom && "No immediate dominator?"); 108 if (IDom != NewIDom) { 109 typename std::vector<DomTreeNodeBase<NodeT>*>::iterator I = 110 std::find(IDom->Children.begin(), IDom->Children.end(), this); 111 assert(I != IDom->Children.end() && 112 "Not in immediate dominator children set!"); 113 // I am no longer your child... 114 IDom->Children.erase(I); 115 116 // Switch to new dominator 117 IDom = NewIDom; 118 IDom->Children.push_back(this); 119 } 120 } 121 122 /// getDFSNumIn/getDFSNumOut - These are an internal implementation detail, do 123 /// not call them. 124 unsigned getDFSNumIn() const { return DFSNumIn; } 125 unsigned getDFSNumOut() const { return DFSNumOut; } 126private: 127 // Return true if this node is dominated by other. Use this only if DFS info 128 // is valid. 129 bool DominatedBy(const DomTreeNodeBase<NodeT> *other) const { 130 return this->DFSNumIn >= other->DFSNumIn && 131 this->DFSNumOut <= other->DFSNumOut; 132 } 133}; 134 135EXTERN_TEMPLATE_INSTANTIATION(class DomTreeNodeBase<BasicBlock>); 136EXTERN_TEMPLATE_INSTANTIATION(class DomTreeNodeBase<MachineBasicBlock>); 137 138template<class NodeT> 139static std::ostream &operator<<(std::ostream &o, 140 const DomTreeNodeBase<NodeT> *Node) { 141 if (Node->getBlock()) 142 WriteAsOperand(o, Node->getBlock(), false); 143 else 144 o << " <<exit node>>"; 145 146 o << " {" << Node->getDFSNumIn() << "," << Node->getDFSNumOut() << "}"; 147 148 return o << "\n"; 149} 150 151template<class NodeT> 152static void PrintDomTree(const DomTreeNodeBase<NodeT> *N, std::ostream &o, 153 unsigned Lev) { 154 o << std::string(2*Lev, ' ') << "[" << Lev << "] " << N; 155 for (typename DomTreeNodeBase<NodeT>::const_iterator I = N->begin(), 156 E = N->end(); I != E; ++I) 157 PrintDomTree<NodeT>(*I, o, Lev+1); 158} 159 160typedef DomTreeNodeBase<BasicBlock> DomTreeNode; 161 162//===----------------------------------------------------------------------===// 163/// DominatorTree - Calculate the immediate dominator tree for a function. 164/// 165 166template<class FuncT, class N> 167void Calculate(DominatorTreeBase<typename GraphTraits<N>::NodeType>& DT, 168 FuncT& F); 169 170template<class NodeT> 171class DominatorTreeBase : public DominatorBase<NodeT> { 172protected: 173 typedef DenseMap<NodeT*, DomTreeNodeBase<NodeT>*> DomTreeNodeMapType; 174 DomTreeNodeMapType DomTreeNodes; 175 DomTreeNodeBase<NodeT> *RootNode; 176 177 bool DFSInfoValid; 178 unsigned int SlowQueries; 179 // Information record used during immediate dominators computation. 180 struct InfoRec { 181 unsigned Semi; 182 unsigned Size; 183 NodeT *Label, *Parent, *Child, *Ancestor; 184 185 std::vector<NodeT*> Bucket; 186 187 InfoRec() : Semi(0), Size(0), Label(0), Parent(0), Child(0), Ancestor(0) {} 188 }; 189 190 DenseMap<NodeT*, NodeT*> IDoms; 191 192 // Vertex - Map the DFS number to the BasicBlock* 193 std::vector<NodeT*> Vertex; 194 195 // Info - Collection of information used during the computation of idoms. 196 DenseMap<NodeT*, InfoRec> Info; 197 198 void reset() { 199 for (typename DomTreeNodeMapType::iterator I = this->DomTreeNodes.begin(), 200 E = DomTreeNodes.end(); I != E; ++I) 201 delete I->second; 202 DomTreeNodes.clear(); 203 IDoms.clear(); 204 this->Roots.clear(); 205 Vertex.clear(); 206 RootNode = 0; 207 } 208 209 // NewBB is split and now it has one successor. Update dominator tree to 210 // reflect this change. 211 template<class N, class GraphT> 212 void Split(DominatorTreeBase<typename GraphT::NodeType>& DT, 213 typename GraphT::NodeType* NewBB) { 214 assert(std::distance(GraphT::child_begin(NewBB), GraphT::child_end(NewBB)) == 1 215 && "NewBB should have a single successor!"); 216 typename GraphT::NodeType* NewBBSucc = *GraphT::child_begin(NewBB); 217 218 std::vector<typename GraphT::NodeType*> PredBlocks; 219 for (typename GraphTraits<Inverse<N> >::ChildIteratorType PI = 220 GraphTraits<Inverse<N> >::child_begin(NewBB), 221 PE = GraphTraits<Inverse<N> >::child_end(NewBB); PI != PE; ++PI) 222 PredBlocks.push_back(*PI); 223 224 assert(!PredBlocks.empty() && "No predblocks??"); 225 226 // The newly inserted basic block will dominate existing basic blocks iff the 227 // PredBlocks dominate all of the non-pred blocks. If all predblocks dominate 228 // the non-pred blocks, then they all must be the same block! 229 // 230 bool NewBBDominatesNewBBSucc = true; 231 { 232 typename GraphT::NodeType* OnePred = PredBlocks[0]; 233 unsigned i = 1, e = PredBlocks.size(); 234 for (i = 1; !DT.isReachableFromEntry(OnePred); ++i) { 235 assert(i != e && "Didn't find reachable pred?"); 236 OnePred = PredBlocks[i]; 237 } 238 239 for (; i != e; ++i) 240 if (PredBlocks[i] != OnePred && DT.isReachableFromEntry(OnePred)) { 241 NewBBDominatesNewBBSucc = false; 242 break; 243 } 244 245 if (NewBBDominatesNewBBSucc) 246 for (typename GraphTraits<Inverse<N> >::ChildIteratorType PI = 247 GraphTraits<Inverse<N> >::child_begin(NewBBSucc), 248 E = GraphTraits<Inverse<N> >::child_end(NewBBSucc); PI != E; ++PI) 249 if (*PI != NewBB && !DT.dominates(NewBBSucc, *PI)) { 250 NewBBDominatesNewBBSucc = false; 251 break; 252 } 253 } 254 255 // The other scenario where the new block can dominate its successors are when 256 // all predecessors of NewBBSucc that are not NewBB are dominated by NewBBSucc 257 // already. 258 if (!NewBBDominatesNewBBSucc) { 259 NewBBDominatesNewBBSucc = true; 260 for (typename GraphTraits<Inverse<N> >::ChildIteratorType PI = 261 GraphTraits<Inverse<N> >::child_begin(NewBBSucc), 262 E = GraphTraits<Inverse<N> >::child_end(NewBBSucc); PI != E; ++PI) 263 if (*PI != NewBB && !DT.dominates(NewBBSucc, *PI)) { 264 NewBBDominatesNewBBSucc = false; 265 break; 266 } 267 } 268 269 // Find NewBB's immediate dominator and create new dominator tree node for 270 // NewBB. 271 NodeT *NewBBIDom = 0; 272 unsigned i = 0; 273 for (i = 0; i < PredBlocks.size(); ++i) 274 if (DT.isReachableFromEntry(PredBlocks[i])) { 275 NewBBIDom = PredBlocks[i]; 276 break; 277 } 278 assert(i != PredBlocks.size() && "No reachable preds?"); 279 for (i = i + 1; i < PredBlocks.size(); ++i) { 280 if (DT.isReachableFromEntry(PredBlocks[i])) 281 NewBBIDom = DT.findNearestCommonDominator(NewBBIDom, PredBlocks[i]); 282 } 283 assert(NewBBIDom && "No immediate dominator found??"); 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 virtual void releaseMemory() { reset(); } 305 306 /// getNode - return the (Post)DominatorTree node for the specified basic 307 /// block. This is the same as using operator[] on this class. 308 /// 309 inline DomTreeNodeBase<NodeT> *getNode(NodeT *BB) const { 310 typename DomTreeNodeMapType::const_iterator I = DomTreeNodes.find(BB); 311 return I != DomTreeNodes.end() ? I->second : 0; 312 } 313 314 /// getRootNode - This returns the entry node for the CFG of the function. If 315 /// this tree represents the post-dominance relations for a function, however, 316 /// this root may be a node with the block == NULL. This is the case when 317 /// there are multiple exit nodes from a particular function. Consumers of 318 /// post-dominance information must be capable of dealing with this 319 /// possibility. 320 /// 321 DomTreeNodeBase<NodeT> *getRootNode() { return RootNode; } 322 const DomTreeNodeBase<NodeT> *getRootNode() const { return RootNode; } 323 324 /// properlyDominates - Returns true iff this dominates N and this != N. 325 /// Note that this is not a constant time operation! 326 /// 327 bool properlyDominates(const DomTreeNodeBase<NodeT> *A, 328 DomTreeNodeBase<NodeT> *B) const { 329 if (A == 0 || B == 0) return false; 330 return dominatedBySlowTreeWalk(A, B); 331 } 332 333 inline bool properlyDominates(NodeT *A, NodeT *B) { 334 return properlyDominates(getNode(A), getNode(B)); 335 } 336 337 bool dominatedBySlowTreeWalk(const DomTreeNodeBase<NodeT> *A, 338 const DomTreeNodeBase<NodeT> *B) const { 339 const DomTreeNodeBase<NodeT> *IDom; 340 if (A == 0 || B == 0) return false; 341 while ((IDom = B->getIDom()) != 0 && IDom != A && IDom != B) 342 B = IDom; // Walk up the tree 343 return IDom != 0; 344 } 345 346 347 /// isReachableFromEntry - Return true if A is dominated by the entry 348 /// block of the function containing it. 349 bool isReachableFromEntry(NodeT* A) { 350 assert (!this->isPostDominator() 351 && "This is not implemented for post dominators"); 352 return dominates(&A->getParent()->front(), A); 353 } 354 355 /// dominates - Returns true iff A dominates B. Note that this is not a 356 /// constant time operation! 357 /// 358 inline bool dominates(const DomTreeNodeBase<NodeT> *A, 359 DomTreeNodeBase<NodeT> *B) { 360 if (B == A) 361 return true; // A node trivially dominates itself. 362 363 if (A == 0 || B == 0) 364 return false; 365 366 if (DFSInfoValid) 367 return B->DominatedBy(A); 368 369 // If we end up with too many slow queries, just update the 370 // DFS numbers on the theory that we are going to keep querying. 371 SlowQueries++; 372 if (SlowQueries > 32) { 373 updateDFSNumbers(); 374 return B->DominatedBy(A); 375 } 376 377 return dominatedBySlowTreeWalk(A, B); 378 } 379 380 inline bool dominates(NodeT *A, NodeT *B) { 381 if (A == B) 382 return true; 383 384 return dominates(getNode(A), getNode(B)); 385 } 386 387 NodeT *getRoot() const { 388 assert(this->Roots.size() == 1 && "Should always have entry node!"); 389 return this->Roots[0]; 390 } 391 392 /// findNearestCommonDominator - Find nearest common dominator basic block 393 /// for basic block A and B. If there is no such block then return NULL. 394 NodeT *findNearestCommonDominator(NodeT *A, NodeT *B) { 395 396 assert (!this->isPostDominator() 397 && "This is not implemented for post dominators"); 398 assert (A->getParent() == B->getParent() 399 && "Two blocks are not in same function"); 400 401 // If either A or B is a entry block then it is nearest common dominator. 402 NodeT &Entry = A->getParent()->front(); 403 if (A == &Entry || B == &Entry) 404 return &Entry; 405 406 // If B dominates A then B is nearest common dominator. 407 if (dominates(B, A)) 408 return B; 409 410 // If A dominates B then A is nearest common dominator. 411 if (dominates(A, B)) 412 return A; 413 414 DomTreeNodeBase<NodeT> *NodeA = getNode(A); 415 DomTreeNodeBase<NodeT> *NodeB = getNode(B); 416 417 // Collect NodeA dominators set. 418 SmallPtrSet<DomTreeNodeBase<NodeT>*, 16> NodeADoms; 419 NodeADoms.insert(NodeA); 420 DomTreeNodeBase<NodeT> *IDomA = NodeA->getIDom(); 421 while (IDomA) { 422 NodeADoms.insert(IDomA); 423 IDomA = IDomA->getIDom(); 424 } 425 426 // Walk NodeB immediate dominators chain and find common dominator node. 427 DomTreeNodeBase<NodeT> *IDomB = NodeB->getIDom(); 428 while(IDomB) { 429 if (NodeADoms.count(IDomB) != 0) 430 return IDomB->getBlock(); 431 432 IDomB = IDomB->getIDom(); 433 } 434 435 return NULL; 436 } 437 438 //===--------------------------------------------------------------------===// 439 // API to update (Post)DominatorTree information based on modifications to 440 // the CFG... 441 442 /// addNewBlock - Add a new node to the dominator tree information. This 443 /// creates a new node as a child of DomBB dominator node,linking it into 444 /// the children list of the immediate dominator. 445 DomTreeNodeBase<NodeT> *addNewBlock(NodeT *BB, NodeT *DomBB) { 446 assert(getNode(BB) == 0 && "Block already in dominator tree!"); 447 DomTreeNodeBase<NodeT> *IDomNode = getNode(DomBB); 448 assert(IDomNode && "Not immediate dominator specified for block!"); 449 DFSInfoValid = false; 450 return DomTreeNodes[BB] = 451 IDomNode->addChild(new DomTreeNodeBase<NodeT>(BB, IDomNode)); 452 } 453 454 /// changeImmediateDominator - This method is used to update the dominator 455 /// tree information when a node's immediate dominator changes. 456 /// 457 void changeImmediateDominator(DomTreeNodeBase<NodeT> *N, 458 DomTreeNodeBase<NodeT> *NewIDom) { 459 assert(N && NewIDom && "Cannot change null node pointers!"); 460 DFSInfoValid = false; 461 N->setIDom(NewIDom); 462 } 463 464 void changeImmediateDominator(NodeT *BB, NodeT *NewBB) { 465 changeImmediateDominator(getNode(BB), getNode(NewBB)); 466 } 467 468 /// eraseNode - Removes a node from the dominator tree. Block must not 469 /// domiante any other blocks. Removes node from its immediate dominator's 470 /// children list. Deletes dominator node associated with basic block BB. 471 void eraseNode(NodeT *BB) { 472 DomTreeNodeBase<NodeT> *Node = getNode(BB); 473 assert (Node && "Removing node that isn't in dominator tree."); 474 assert (Node->getChildren().empty() && "Node is not a leaf node."); 475 476 // Remove node from immediate dominator's children list. 477 DomTreeNodeBase<NodeT> *IDom = Node->getIDom(); 478 if (IDom) { 479 typename std::vector<DomTreeNodeBase<NodeT>*>::iterator I = 480 std::find(IDom->Children.begin(), IDom->Children.end(), Node); 481 assert(I != IDom->Children.end() && 482 "Not in immediate dominator children set!"); 483 // I am no longer your child... 484 IDom->Children.erase(I); 485 } 486 487 DomTreeNodes.erase(BB); 488 delete Node; 489 } 490 491 /// removeNode - Removes a node from the dominator tree. Block must not 492 /// dominate any other blocks. Invalidates any node pointing to removed 493 /// block. 494 void removeNode(NodeT *BB) { 495 assert(getNode(BB) && "Removing node that isn't in dominator tree."); 496 DomTreeNodes.erase(BB); 497 } 498 499 /// splitBlock - BB is split and now it has one successor. Update dominator 500 /// tree to reflect this change. 501 void splitBlock(NodeT* NewBB) { 502 if (this->IsPostDominators) 503 this->Split<Inverse<NodeT*>, GraphTraits<Inverse<NodeT*> > >(*this, NewBB); 504 else 505 this->Split<NodeT*, GraphTraits<NodeT*> >(*this, NewBB); 506 } 507 508 /// print - Convert to human readable form 509 /// 510 virtual void print(std::ostream &o, const Module* ) const { 511 o << "=============================--------------------------------\n"; 512 if (this->isPostDominator()) 513 o << "Inorder PostDominator Tree: "; 514 else 515 o << "Inorder Dominator Tree: "; 516 if (this->DFSInfoValid) 517 o << "DFSNumbers invalid: " << SlowQueries << " slow queries."; 518 o << "\n"; 519 520 PrintDomTree<NodeT>(getRootNode(), o, 1); 521 } 522 523 void print(std::ostream *OS, const Module* M = 0) const { 524 if (OS) print(*OS, M); 525 } 526 527 virtual void dump() { 528 print(llvm::cerr); 529 } 530 531protected: 532 template<class GraphT> 533 friend void Compress(DominatorTreeBase<typename GraphT::NodeType>& DT, 534 typename GraphT::NodeType* VIn); 535 536 template<class GraphT> 537 friend typename GraphT::NodeType* Eval( 538 DominatorTreeBase<typename GraphT::NodeType>& DT, 539 typename GraphT::NodeType* V); 540 541 template<class GraphT> 542 friend void Link(DominatorTreeBase<typename GraphT::NodeType>& DT, 543 typename GraphT::NodeType* V, 544 typename GraphT::NodeType* W, 545 typename DominatorTreeBase<typename GraphT::NodeType>::InfoRec &WInfo); 546 547 template<class GraphT> 548 friend unsigned DFSPass(DominatorTreeBase<typename GraphT::NodeType>& DT, 549 typename GraphT::NodeType* V, 550 unsigned N); 551 552 template<class FuncT, class N> 553 friend void Calculate(DominatorTreeBase<typename GraphTraits<N>::NodeType>& DT, 554 FuncT& F); 555 556 /// updateDFSNumbers - Assign In and Out numbers to the nodes while walking 557 /// dominator tree in dfs order. 558 void updateDFSNumbers() { 559 unsigned DFSNum = 0; 560 561 SmallVector<std::pair<DomTreeNodeBase<NodeT>*, 562 typename DomTreeNodeBase<NodeT>::iterator>, 32> WorkStack; 563 564 for (unsigned i = 0, e = this->Roots.size(); i != e; ++i) { 565 DomTreeNodeBase<NodeT> *ThisRoot = getNode(this->Roots[i]); 566 WorkStack.push_back(std::make_pair(ThisRoot, ThisRoot->begin())); 567 ThisRoot->DFSNumIn = DFSNum++; 568 569 while (!WorkStack.empty()) { 570 DomTreeNodeBase<NodeT> *Node = WorkStack.back().first; 571 typename DomTreeNodeBase<NodeT>::iterator ChildIt = 572 WorkStack.back().second; 573 574 // If we visited all of the children of this node, "recurse" back up the 575 // stack setting the DFOutNum. 576 if (ChildIt == Node->end()) { 577 Node->DFSNumOut = DFSNum++; 578 WorkStack.pop_back(); 579 } else { 580 // Otherwise, recursively visit this child. 581 DomTreeNodeBase<NodeT> *Child = *ChildIt; 582 ++WorkStack.back().second; 583 584 WorkStack.push_back(std::make_pair(Child, Child->begin())); 585 Child->DFSNumIn = DFSNum++; 586 } 587 } 588 } 589 590 SlowQueries = 0; 591 DFSInfoValid = true; 592 } 593 594 DomTreeNodeBase<NodeT> *getNodeForBlock(NodeT *BB) { 595 if (DomTreeNodeBase<NodeT> *BBNode = this->DomTreeNodes[BB]) 596 return BBNode; 597 598 // Haven't calculated this node yet? Get or calculate the node for the 599 // immediate dominator. 600 NodeT *IDom = getIDom(BB); 601 DomTreeNodeBase<NodeT> *IDomNode = getNodeForBlock(IDom); 602 603 // Add a new tree node for this BasicBlock, and link it as a child of 604 // IDomNode 605 DomTreeNodeBase<NodeT> *C = new DomTreeNodeBase<NodeT>(BB, IDomNode); 606 return this->DomTreeNodes[BB] = IDomNode->addChild(C); 607 } 608 609 inline NodeT *getIDom(NodeT *BB) const { 610 typename DenseMap<NodeT*, NodeT*>::const_iterator I = IDoms.find(BB); 611 return I != IDoms.end() ? I->second : 0; 612 } 613 614 inline void addRoot(NodeT* BB) { 615 // Unreachable block is not a root node. 616 if (!isa<UnreachableInst>(&BB->back())) 617 this->Roots.push_back(BB); 618 } 619 620public: 621 /// recalculate - compute a dominator tree for the given function 622 template<class FT> 623 void recalculate(FT& F) { 624 if (!this->IsPostDominators) { 625 reset(); 626 627 // Initialize roots 628 this->Roots.push_back(&F.front()); 629 this->IDoms[&F.front()] = 0; 630 this->DomTreeNodes[&F.front()] = 0; 631 this->Vertex.push_back(0); 632 633 Calculate<FT, NodeT*>(*this, F); 634 635 updateDFSNumbers(); 636 } else { 637 reset(); // Reset from the last time we were run... 638 639 // Initialize the roots list 640 for (typename FT::iterator I = F.begin(), E = F.end(); I != E; ++I) { 641 if (std::distance(GraphTraits<FT*>::child_begin(I), 642 GraphTraits<FT*>::child_end(I)) == 0) 643 addRoot(I); 644 645 // Prepopulate maps so that we don't get iterator invalidation issues later. 646 this->IDoms[I] = 0; 647 this->DomTreeNodes[I] = 0; 648 } 649 650 this->Vertex.push_back(0); 651 652 Calculate<FT, Inverse<NodeT*> >(*this, F); 653 } 654 } 655}; 656 657EXTERN_TEMPLATE_INSTANTIATION(class DominatorTreeBase<BasicBlock>); 658 659//===------------------------------------- 660/// DominatorTree Class - Concrete subclass of DominatorTreeBase that is used to 661/// compute a normal dominator tree. 662/// 663class DominatorTree : public FunctionPass { 664public: 665 static char ID; // Pass ID, replacement for typeid 666 DominatorTreeBase<BasicBlock>* DT; 667 668 DominatorTree() : FunctionPass(intptr_t(&ID)) { 669 DT = new DominatorTreeBase<BasicBlock>(false); 670 } 671 672 ~DominatorTree() { 673 DT->releaseMemory(); 674 delete DT; 675 } 676 677 DominatorTreeBase<BasicBlock>& getBase() { return *DT; } 678 679 /// getRoots - Return the root blocks of the current CFG. This may include 680 /// multiple blocks if we are computing post dominators. For forward 681 /// dominators, this will always be a single block (the entry node). 682 /// 683 inline const std::vector<BasicBlock*> &getRoots() const { 684 return DT->getRoots(); 685 } 686 687 inline BasicBlock *getRoot() const { 688 return DT->getRoot(); 689 } 690 691 inline DomTreeNode *getRootNode() const { 692 return DT->getRootNode(); 693 } 694 695 virtual bool runOnFunction(Function &F); 696 697 virtual void getAnalysisUsage(AnalysisUsage &AU) const { 698 AU.setPreservesAll(); 699 } 700 701 inline bool dominates(DomTreeNode* A, DomTreeNode* B) const { 702 return DT->dominates(A, B); 703 } 704 705 inline bool dominates(BasicBlock* A, BasicBlock* B) const { 706 return DT->dominates(A, B); 707 } 708 709 // dominates - Return true if A dominates B. This performs the 710 // special checks necessary if A and B are in the same basic block. 711 bool dominates(Instruction *A, Instruction *B) const { 712 BasicBlock *BBA = A->getParent(), *BBB = B->getParent(); 713 if (BBA != BBB) return DT->dominates(BBA, BBB); 714 715 // It is not possible to determine dominance between two PHI nodes 716 // based on their ordering. 717 if (isa<PHINode>(A) && isa<PHINode>(B)) 718 return false; 719 720 // Loop through the basic block until we find A or B. 721 BasicBlock::iterator I = BBA->begin(); 722 for (; &*I != A && &*I != B; ++I) /*empty*/; 723 724 //if(!DT.IsPostDominators) { 725 // A dominates B if it is found first in the basic block. 726 return &*I == A; 727 //} else { 728 // // A post-dominates B if B is found first in the basic block. 729 // return &*I == B; 730 //} 731 } 732 733 inline bool properlyDominates(const DomTreeNode* A, DomTreeNode* B) const { 734 return DT->properlyDominates(A, B); 735 } 736 737 inline bool properlyDominates(BasicBlock* A, BasicBlock* B) const { 738 return DT->properlyDominates(A, B); 739 } 740 741 /// findNearestCommonDominator - Find nearest common dominator basic block 742 /// for basic block A and B. If there is no such block then return NULL. 743 inline BasicBlock *findNearestCommonDominator(BasicBlock *A, BasicBlock *B) { 744 return DT->findNearestCommonDominator(A, B); 745 } 746 747 inline DomTreeNode *operator[](BasicBlock *BB) const { 748 return DT->getNode(BB); 749 } 750 751 /// getNode - return the (Post)DominatorTree node for the specified basic 752 /// block. This is the same as using operator[] on this class. 753 /// 754 inline DomTreeNode *getNode(BasicBlock *BB) const { 755 return DT->getNode(BB); 756 } 757 758 /// addNewBlock - Add a new node to the dominator tree information. This 759 /// creates a new node as a child of DomBB dominator node,linking it into 760 /// the children list of the immediate dominator. 761 inline DomTreeNode *addNewBlock(BasicBlock *BB, BasicBlock *DomBB) { 762 return DT->addNewBlock(BB, DomBB); 763 } 764 765 /// changeImmediateDominator - This method is used to update the dominator 766 /// tree information when a node's immediate dominator changes. 767 /// 768 inline void changeImmediateDominator(BasicBlock *N, BasicBlock* NewIDom) { 769 DT->changeImmediateDominator(N, NewIDom); 770 } 771 772 inline void changeImmediateDominator(DomTreeNode *N, DomTreeNode* NewIDom) { 773 DT->changeImmediateDominator(N, NewIDom); 774 } 775 776 /// eraseNode - Removes a node from the dominator tree. Block must not 777 /// domiante any other blocks. Removes node from its immediate dominator's 778 /// children list. Deletes dominator node associated with basic block BB. 779 inline void eraseNode(BasicBlock *BB) { 780 DT->eraseNode(BB); 781 } 782 783 /// splitBlock - BB is split and now it has one successor. Update dominator 784 /// tree to reflect this change. 785 inline void splitBlock(BasicBlock* NewBB) { 786 DT->splitBlock(NewBB); 787 } 788 789 790 virtual void releaseMemory() { 791 DT->releaseMemory(); 792 } 793 794 virtual void print(std::ostream &OS, const Module* M= 0) const { 795 DT->print(OS, M); 796 } 797}; 798 799//===------------------------------------- 800/// DominatorTree GraphTraits specialization so the DominatorTree can be 801/// iterable by generic graph iterators. 802/// 803template <> struct GraphTraits<DomTreeNode *> { 804 typedef DomTreeNode NodeType; 805 typedef NodeType::iterator ChildIteratorType; 806 807 static NodeType *getEntryNode(NodeType *N) { 808 return N; 809 } 810 static inline ChildIteratorType child_begin(NodeType* N) { 811 return N->begin(); 812 } 813 static inline ChildIteratorType child_end(NodeType* N) { 814 return N->end(); 815 } 816}; 817 818template <> struct GraphTraits<DominatorTree*> 819 : public GraphTraits<DomTreeNode *> { 820 static NodeType *getEntryNode(DominatorTree *DT) { 821 return DT->getRootNode(); 822 } 823}; 824 825 826//===----------------------------------------------------------------------===// 827/// DominanceFrontierBase - Common base class for computing forward and inverse 828/// dominance frontiers for a function. 829/// 830class DominanceFrontierBase : public FunctionPass { 831public: 832 typedef std::set<BasicBlock*> DomSetType; // Dom set for a bb 833 typedef std::map<BasicBlock*, DomSetType> DomSetMapType; // Dom set map 834protected: 835 DomSetMapType Frontiers; 836 std::vector<BasicBlock*> Roots; 837 const bool IsPostDominators; 838 839public: 840 DominanceFrontierBase(intptr_t ID, bool isPostDom) 841 : FunctionPass(ID), IsPostDominators(isPostDom) {} 842 843 /// getRoots - Return the root blocks of the current CFG. This may include 844 /// multiple blocks if we are computing post dominators. For forward 845 /// dominators, this will always be a single block (the entry node). 846 /// 847 inline const std::vector<BasicBlock*> &getRoots() const { return Roots; } 848 849 /// isPostDominator - Returns true if analysis based of postdoms 850 /// 851 bool isPostDominator() const { return IsPostDominators; } 852 853 virtual void releaseMemory() { Frontiers.clear(); } 854 855 // Accessor interface: 856 typedef DomSetMapType::iterator iterator; 857 typedef DomSetMapType::const_iterator const_iterator; 858 iterator begin() { return Frontiers.begin(); } 859 const_iterator begin() const { return Frontiers.begin(); } 860 iterator end() { return Frontiers.end(); } 861 const_iterator end() const { return Frontiers.end(); } 862 iterator find(BasicBlock *B) { return Frontiers.find(B); } 863 const_iterator find(BasicBlock *B) const { return Frontiers.find(B); } 864 865 void addBasicBlock(BasicBlock *BB, const DomSetType &frontier) { 866 assert(find(BB) == end() && "Block already in DominanceFrontier!"); 867 Frontiers.insert(std::make_pair(BB, frontier)); 868 } 869 870 /// removeBlock - Remove basic block BB's frontier. 871 void removeBlock(BasicBlock *BB) { 872 assert(find(BB) != end() && "Block is not in DominanceFrontier!"); 873 for (iterator I = begin(), E = end(); I != E; ++I) 874 I->second.erase(BB); 875 Frontiers.erase(BB); 876 } 877 878 void addToFrontier(iterator I, BasicBlock *Node) { 879 assert(I != end() && "BB is not in DominanceFrontier!"); 880 I->second.insert(Node); 881 } 882 883 void removeFromFrontier(iterator I, BasicBlock *Node) { 884 assert(I != end() && "BB is not in DominanceFrontier!"); 885 assert(I->second.count(Node) && "Node is not in DominanceFrontier of BB"); 886 I->second.erase(Node); 887 } 888 889 /// print - Convert to human readable form 890 /// 891 virtual void print(std::ostream &OS, const Module* = 0) const; 892 void print(std::ostream *OS, const Module* M = 0) const { 893 if (OS) print(*OS, M); 894 } 895 virtual void dump(); 896}; 897 898 899//===------------------------------------- 900/// DominanceFrontier Class - Concrete subclass of DominanceFrontierBase that is 901/// used to compute a forward dominator frontiers. 902/// 903class DominanceFrontier : public DominanceFrontierBase { 904public: 905 static char ID; // Pass ID, replacement for typeid 906 DominanceFrontier() : 907 DominanceFrontierBase(intptr_t(&ID), false) {} 908 909 BasicBlock *getRoot() const { 910 assert(Roots.size() == 1 && "Should always have entry node!"); 911 return Roots[0]; 912 } 913 914 virtual bool runOnFunction(Function &) { 915 Frontiers.clear(); 916 DominatorTree &DT = getAnalysis<DominatorTree>(); 917 Roots = DT.getRoots(); 918 assert(Roots.size() == 1 && "Only one entry block for forward domfronts!"); 919 calculate(DT, DT[Roots[0]]); 920 return false; 921 } 922 923 virtual void getAnalysisUsage(AnalysisUsage &AU) const { 924 AU.setPreservesAll(); 925 AU.addRequired<DominatorTree>(); 926 } 927 928 /// splitBlock - BB is split and now it has one successor. Update dominance 929 /// frontier to reflect this change. 930 void splitBlock(BasicBlock *BB); 931 932 /// BasicBlock BB's new dominator is NewBB. Update BB's dominance frontier 933 /// to reflect this change. 934 void changeImmediateDominator(BasicBlock *BB, BasicBlock *NewBB, 935 DominatorTree *DT) { 936 // NewBB is now dominating BB. Which means BB's dominance 937 // frontier is now part of NewBB's dominance frontier. However, BB 938 // itself is not member of NewBB's dominance frontier. 939 DominanceFrontier::iterator NewDFI = find(NewBB); 940 DominanceFrontier::iterator DFI = find(BB); 941 DominanceFrontier::DomSetType BBSet = DFI->second; 942 for (DominanceFrontier::DomSetType::iterator BBSetI = BBSet.begin(), 943 BBSetE = BBSet.end(); BBSetI != BBSetE; ++BBSetI) { 944 BasicBlock *DFMember = *BBSetI; 945 // Insert only if NewBB dominates DFMember. 946 if (!DT->dominates(NewBB, DFMember)) 947 NewDFI->second.insert(DFMember); 948 } 949 NewDFI->second.erase(BB); 950 } 951 952private: 953 const DomSetType &calculate(const DominatorTree &DT, 954 const DomTreeNode *Node); 955}; 956 957 958} // End llvm namespace 959 960#endif 961