Dominators.h revision 50cdabcfd52e88381ade61450d98a1c757195bef
1//===- llvm/Analysis/Dominators.h - Dominator Info Calculation --*- C++ -*-===// 2// 3// The LLVM Compiler Infrastructure 4// 5// This file was developed by the LLVM research group and is distributed under 6// the University of Illinois Open Source 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 <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 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 void setIDom(DomTreeNodeBase<NodeT> *NewIDom) { 106 assert(IDom && "No immediate dominator?"); 107 if (IDom != NewIDom) { 108 typename std::vector<DomTreeNodeBase<NodeT>*>::iterator I = 109 std::find(IDom->Children.begin(), IDom->Children.end(), this); 110 assert(I != IDom->Children.end() && 111 "Not in immediate dominator children set!"); 112 // I am no longer your child... 113 IDom->Children.erase(I); 114 115 // Switch to new dominator 116 IDom = NewIDom; 117 IDom->Children.push_back(this); 118 } 119 } 120 121 /// getDFSNumIn/getDFSNumOut - These are an internal implementation detail, do 122 /// not call them. 123 unsigned getDFSNumIn() const { return DFSNumIn; } 124 unsigned getDFSNumOut() const { return DFSNumOut; } 125private: 126 // Return true if this node is dominated by other. Use this only if DFS info 127 // is valid. 128 bool DominatedBy(const DomTreeNodeBase<NodeT> *other) const { 129 return this->DFSNumIn >= other->DFSNumIn && 130 this->DFSNumOut <= other->DFSNumOut; 131 } 132}; 133 134EXTERN_TEMPLATE_INSTANTIATION(class DomTreeNodeBase<BasicBlock>); 135EXTERN_TEMPLATE_INSTANTIATION(class DomTreeNodeBase<MachineBasicBlock>); 136 137template<class NodeT> 138static std::ostream &operator<<(std::ostream &o, 139 const DomTreeNodeBase<NodeT> *Node) { 140 if (Node->getBlock()) 141 WriteAsOperand(o, Node->getBlock(), false); 142 else 143 o << " <<exit node>>"; 144 145 o << " {" << Node->getDFSNumIn() << "," << Node->getDFSNumOut() << "}"; 146 147 return o << "\n"; 148} 149 150template<class NodeT> 151static void PrintDomTree(const DomTreeNodeBase<NodeT> *N, std::ostream &o, 152 unsigned Lev) { 153 o << std::string(2*Lev, ' ') << "[" << Lev << "] " << N; 154 for (typename DomTreeNodeBase<NodeT>::const_iterator I = N->begin(), 155 E = N->end(); I != E; ++I) 156 PrintDomTree<NodeT>(*I, o, Lev+1); 157} 158 159typedef DomTreeNodeBase<BasicBlock> DomTreeNode; 160 161//===----------------------------------------------------------------------===// 162/// DominatorTree - Calculate the immediate dominator tree for a function. 163/// 164 165template<class FuncT, class N> 166void Calculate(DominatorTreeBase<typename GraphTraits<N>::NodeType>& DT, 167 FuncT& F); 168 169template<class NodeT> 170class DominatorTreeBase : public DominatorBase<NodeT> { 171protected: 172 typedef DenseMap<NodeT*, DomTreeNodeBase<NodeT>*> DomTreeNodeMapType; 173 DomTreeNodeMapType DomTreeNodes; 174 DomTreeNodeBase<NodeT> *RootNode; 175 176 bool DFSInfoValid; 177 unsigned int SlowQueries; 178 // Information record used during immediate dominators computation. 179 struct InfoRec { 180 unsigned Semi; 181 unsigned Size; 182 NodeT *Label, *Parent, *Child, *Ancestor; 183 184 std::vector<NodeT*> Bucket; 185 186 InfoRec() : Semi(0), Size(0), Label(0), Parent(0), Child(0), Ancestor(0) {} 187 }; 188 189 DenseMap<NodeT*, NodeT*> IDoms; 190 191 // Vertex - Map the DFS number to the BasicBlock* 192 std::vector<NodeT*> Vertex; 193 194 // Info - Collection of information used during the computation of idoms. 195 DenseMap<NodeT*, InfoRec> Info; 196 197 void reset() { 198 for (typename DomTreeNodeMapType::iterator I = this->DomTreeNodes.begin(), 199 E = DomTreeNodes.end(); I != E; ++I) 200 delete I->second; 201 DomTreeNodes.clear(); 202 IDoms.clear(); 203 this->Roots.clear(); 204 Vertex.clear(); 205 RootNode = 0; 206 } 207 208 // NewBB is split and now it has one successor. Update dominator tree to 209 // reflect this change. 210 template<class N, class GraphT> 211 void Split(DominatorTreeBase<typename GraphT::NodeType>& DT, 212 typename GraphT::NodeType* NewBB) { 213 assert(std::distance(GraphT::child_begin(NewBB), GraphT::child_end(NewBB)) == 1 214 && "NewBB should have a single successor!"); 215 typename GraphT::NodeType* NewBBSucc = *GraphT::child_begin(NewBB); 216 217 std::vector<typename GraphT::NodeType*> PredBlocks; 218 for (typename GraphTraits<Inverse<N> >::ChildIteratorType PI = 219 GraphTraits<Inverse<N> >::child_begin(NewBB), 220 PE = GraphTraits<Inverse<N> >::child_end(NewBB); PI != PE; ++PI) 221 PredBlocks.push_back(*PI); 222 223 assert(!PredBlocks.empty() && "No predblocks??"); 224 225 // The newly inserted basic block will dominate existing basic blocks iff the 226 // PredBlocks dominate all of the non-pred blocks. If all predblocks dominate 227 // the non-pred blocks, then they all must be the same block! 228 // 229 bool NewBBDominatesNewBBSucc = true; 230 { 231 typename GraphT::NodeType* OnePred = PredBlocks[0]; 232 unsigned i = 1, e = PredBlocks.size(); 233 for (i = 1; !DT.isReachableFromEntry(OnePred); ++i) { 234 assert(i != e && "Didn't find reachable pred?"); 235 OnePred = PredBlocks[i]; 236 } 237 238 for (; i != e; ++i) 239 if (PredBlocks[i] != OnePred && DT.isReachableFromEntry(OnePred)) { 240 NewBBDominatesNewBBSucc = false; 241 break; 242 } 243 244 if (NewBBDominatesNewBBSucc) 245 for (typename GraphTraits<Inverse<N> >::ChildIteratorType PI = 246 GraphTraits<Inverse<N> >::child_begin(NewBBSucc), 247 E = GraphTraits<Inverse<N> >::child_end(NewBBSucc); PI != E; ++PI) 248 if (*PI != NewBB && !DT.dominates(NewBBSucc, *PI)) { 249 NewBBDominatesNewBBSucc = false; 250 break; 251 } 252 } 253 254 // The other scenario where the new block can dominate its successors are when 255 // all predecessors of NewBBSucc that are not NewBB are dominated by NewBBSucc 256 // already. 257 if (!NewBBDominatesNewBBSucc) { 258 NewBBDominatesNewBBSucc = true; 259 for (typename GraphTraits<Inverse<N> >::ChildIteratorType PI = 260 GraphTraits<Inverse<N> >::child_begin(NewBBSucc), 261 E = GraphTraits<Inverse<N> >::child_end(NewBBSucc); PI != E; ++PI) 262 if (*PI != NewBB && !DT.dominates(NewBBSucc, *PI)) { 263 NewBBDominatesNewBBSucc = false; 264 break; 265 } 266 } 267 268 // Find NewBB's immediate dominator and create new dominator tree node for 269 // NewBB. 270 NodeT *NewBBIDom = 0; 271 unsigned i = 0; 272 for (i = 0; i < PredBlocks.size(); ++i) 273 if (DT.isReachableFromEntry(PredBlocks[i])) { 274 NewBBIDom = PredBlocks[i]; 275 break; 276 } 277 assert(i != PredBlocks.size() && "No reachable preds?"); 278 for (i = i + 1; i < PredBlocks.size(); ++i) { 279 if (DT.isReachableFromEntry(PredBlocks[i])) 280 NewBBIDom = DT.findNearestCommonDominator(NewBBIDom, PredBlocks[i]); 281 } 282 assert(NewBBIDom && "No immediate dominator found??"); 283 284 // Create the new dominator tree node... and set the idom of NewBB. 285 DomTreeNodeBase<NodeT> *NewBBNode = DT.addNewBlock(NewBB, NewBBIDom); 286 287 // If NewBB strictly dominates other blocks, then it is now the immediate 288 // dominator of NewBBSucc. Update the dominator tree as appropriate. 289 if (NewBBDominatesNewBBSucc) { 290 DomTreeNodeBase<NodeT> *NewBBSuccNode = DT.getNode(NewBBSucc); 291 DT.changeImmediateDominator(NewBBSuccNode, NewBBNode); 292 } 293 } 294 295public: 296 DominatorTreeBase(bool isPostDom) 297 : DominatorBase<NodeT>(isPostDom), DFSInfoValid(false), SlowQueries(0) {} 298 virtual ~DominatorTreeBase() { reset(); } 299 300 // FIXME: Should remove this 301 virtual bool runOnFunction(Function &F) { return false; } 302 303 virtual void releaseMemory() { reset(); } 304 305 /// getNode - return the (Post)DominatorTree node for the specified basic 306 /// block. This is the same as using operator[] on this class. 307 /// 308 inline DomTreeNodeBase<NodeT> *getNode(NodeT *BB) const { 309 typename DomTreeNodeMapType::const_iterator I = DomTreeNodes.find(BB); 310 return I != DomTreeNodes.end() ? I->second : 0; 311 } 312 313 /// getRootNode - This returns the entry node for the CFG of the function. If 314 /// this tree represents the post-dominance relations for a function, however, 315 /// this root may be a node with the block == NULL. This is the case when 316 /// there are multiple exit nodes from a particular function. Consumers of 317 /// post-dominance information must be capable of dealing with this 318 /// possibility. 319 /// 320 DomTreeNodeBase<NodeT> *getRootNode() { return RootNode; } 321 const DomTreeNodeBase<NodeT> *getRootNode() const { return RootNode; } 322 323 /// properlyDominates - Returns true iff this dominates N and this != N. 324 /// Note that this is not a constant time operation! 325 /// 326 bool properlyDominates(const DomTreeNodeBase<NodeT> *A, 327 DomTreeNodeBase<NodeT> *B) const { 328 if (A == 0 || B == 0) return false; 329 return dominatedBySlowTreeWalk(A, B); 330 } 331 332 inline bool properlyDominates(NodeT *A, NodeT *B) { 333 return properlyDominates(getNode(A), getNode(B)); 334 } 335 336 bool dominatedBySlowTreeWalk(const DomTreeNodeBase<NodeT> *A, 337 const DomTreeNodeBase<NodeT> *B) const { 338 const DomTreeNodeBase<NodeT> *IDom; 339 if (A == 0 || B == 0) return false; 340 while ((IDom = B->getIDom()) != 0 && IDom != A && IDom != B) 341 B = IDom; // Walk up the tree 342 return IDom != 0; 343 } 344 345 346 /// isReachableFromEntry - Return true if A is dominated by the entry 347 /// block of the function containing it. 348 bool isReachableFromEntry(NodeT* A) { 349 assert (!this->isPostDominator() 350 && "This is not implemented for post dominators"); 351 return dominates(&A->getParent()->front(), A); 352 } 353 354 /// dominates - Returns true iff A dominates B. Note that this is not a 355 /// constant time operation! 356 /// 357 inline bool dominates(const DomTreeNodeBase<NodeT> *A, 358 DomTreeNodeBase<NodeT> *B) { 359 if (B == A) 360 return true; // A node trivially dominates itself. 361 362 if (A == 0 || B == 0) 363 return false; 364 365 if (DFSInfoValid) 366 return B->DominatedBy(A); 367 368 // If we end up with too many slow queries, just update the 369 // DFS numbers on the theory that we are going to keep querying. 370 SlowQueries++; 371 if (SlowQueries > 32) { 372 updateDFSNumbers(); 373 return B->DominatedBy(A); 374 } 375 376 return dominatedBySlowTreeWalk(A, B); 377 } 378 379 inline bool dominates(NodeT *A, NodeT *B) { 380 if (A == B) 381 return true; 382 383 return dominates(getNode(A), getNode(B)); 384 } 385 386 NodeT *getRoot() const { 387 assert(this->Roots.size() == 1 && "Should always have entry node!"); 388 return this->Roots[0]; 389 } 390 391 /// findNearestCommonDominator - Find nearest common dominator basic block 392 /// for basic block A and B. If there is no such block then return NULL. 393 NodeT *findNearestCommonDominator(NodeT *A, NodeT *B) { 394 395 assert (!this->isPostDominator() 396 && "This is not implemented for post dominators"); 397 assert (A->getParent() == B->getParent() 398 && "Two blocks are not in same function"); 399 400 // If either A or B is a entry block then it is nearest common dominator. 401 NodeT &Entry = A->getParent()->front(); 402 if (A == &Entry || B == &Entry) 403 return &Entry; 404 405 // If B dominates A then B is nearest common dominator. 406 if (dominates(B, A)) 407 return B; 408 409 // If A dominates B then A is nearest common dominator. 410 if (dominates(A, B)) 411 return A; 412 413 DomTreeNodeBase<NodeT> *NodeA = getNode(A); 414 DomTreeNodeBase<NodeT> *NodeB = getNode(B); 415 416 // Collect NodeA dominators set. 417 SmallPtrSet<DomTreeNodeBase<NodeT>*, 16> NodeADoms; 418 NodeADoms.insert(NodeA); 419 DomTreeNodeBase<NodeT> *IDomA = NodeA->getIDom(); 420 while (IDomA) { 421 NodeADoms.insert(IDomA); 422 IDomA = IDomA->getIDom(); 423 } 424 425 // Walk NodeB immediate dominators chain and find common dominator node. 426 DomTreeNodeBase<NodeT> *IDomB = NodeB->getIDom(); 427 while(IDomB) { 428 if (NodeADoms.count(IDomB) != 0) 429 return IDomB->getBlock(); 430 431 IDomB = IDomB->getIDom(); 432 } 433 434 return NULL; 435 } 436 437 //===--------------------------------------------------------------------===// 438 // API to update (Post)DominatorTree information based on modifications to 439 // the CFG... 440 441 /// addNewBlock - Add a new node to the dominator tree information. This 442 /// creates a new node as a child of DomBB dominator node,linking it into 443 /// the children list of the immediate dominator. 444 DomTreeNodeBase<NodeT> *addNewBlock(NodeT *BB, NodeT *DomBB) { 445 assert(getNode(BB) == 0 && "Block already in dominator tree!"); 446 DomTreeNodeBase<NodeT> *IDomNode = getNode(DomBB); 447 assert(IDomNode && "Not immediate dominator specified for block!"); 448 DFSInfoValid = false; 449 return DomTreeNodes[BB] = 450 IDomNode->addChild(new DomTreeNodeBase<NodeT>(BB, IDomNode)); 451 } 452 453 /// changeImmediateDominator - This method is used to update the dominator 454 /// tree information when a node's immediate dominator changes. 455 /// 456 void changeImmediateDominator(DomTreeNodeBase<NodeT> *N, 457 DomTreeNodeBase<NodeT> *NewIDom) { 458 assert(N && NewIDom && "Cannot change null node pointers!"); 459 DFSInfoValid = false; 460 N->setIDom(NewIDom); 461 } 462 463 void changeImmediateDominator(NodeT *BB, NodeT *NewBB) { 464 changeImmediateDominator(getNode(BB), getNode(NewBB)); 465 } 466 467 /// eraseNode - Removes a node from the dominator tree. Block must not 468 /// domiante any other blocks. Removes node from its immediate dominator's 469 /// children list. Deletes dominator node associated with basic block BB. 470 void eraseNode(NodeT *BB) { 471 DomTreeNodeBase<NodeT> *Node = getNode(BB); 472 assert (Node && "Removing node that isn't in dominator tree."); 473 assert (Node->getChildren().empty() && "Node is not a leaf node."); 474 475 // Remove node from immediate dominator's children list. 476 DomTreeNodeBase<NodeT> *IDom = Node->getIDom(); 477 if (IDom) { 478 typename std::vector<DomTreeNodeBase<NodeT>*>::iterator I = 479 std::find(IDom->Children.begin(), IDom->Children.end(), Node); 480 assert(I != IDom->Children.end() && 481 "Not in immediate dominator children set!"); 482 // I am no longer your child... 483 IDom->Children.erase(I); 484 } 485 486 DomTreeNodes.erase(BB); 487 delete Node; 488 } 489 490 /// removeNode - Removes a node from the dominator tree. Block must not 491 /// dominate any other blocks. Invalidates any node pointing to removed 492 /// block. 493 void removeNode(NodeT *BB) { 494 assert(getNode(BB) && "Removing node that isn't in dominator tree."); 495 DomTreeNodes.erase(BB); 496 } 497 498 /// splitBlock - BB is split and now it has one successor. Update dominator 499 /// tree to reflect this change. 500 void splitBlock(NodeT* NewBB) { 501 if (this->IsPostDominators) 502 this->Split<Inverse<NodeT*>, GraphTraits<Inverse<NodeT*> > >(*this, NewBB); 503 else 504 this->Split<NodeT*, GraphTraits<NodeT*> >(*this, NewBB); 505 } 506 507 /// print - Convert to human readable form 508 /// 509 virtual void print(std::ostream &o, const Module* ) const { 510 o << "=============================--------------------------------\n"; 511 o << "Inorder Dominator Tree: "; 512 if (this->DFSInfoValid) 513 o << "DFSNumbers invalid: " << SlowQueries << " slow queries."; 514 o << "\n"; 515 516 PrintDomTree<NodeT>(getRootNode(), o, 1); 517 } 518 519 void print(std::ostream *OS, const Module* M = 0) const { 520 if (OS) print(*OS, M); 521 } 522 523 virtual void dump() { 524 print(llvm::cerr); 525 } 526 527protected: 528 template<class GraphT> 529 friend void Compress(DominatorTreeBase<typename GraphT::NodeType>& DT, 530 typename GraphT::NodeType* VIn); 531 532 template<class GraphT> 533 friend typename GraphT::NodeType* Eval( 534 DominatorTreeBase<typename GraphT::NodeType>& DT, 535 typename GraphT::NodeType* V); 536 537 template<class GraphT> 538 friend void Link(DominatorTreeBase<typename GraphT::NodeType>& DT, 539 typename GraphT::NodeType* V, 540 typename GraphT::NodeType* W, 541 typename DominatorTreeBase<typename GraphT::NodeType>::InfoRec &WInfo); 542 543 template<class GraphT> 544 friend unsigned DFSPass(DominatorTreeBase<typename GraphT::NodeType>& DT, 545 typename GraphT::NodeType* V, 546 unsigned N); 547 548 template<class FuncT, class N> 549 friend void Calculate(DominatorTreeBase<typename GraphTraits<N>::NodeType>& DT, 550 FuncT& F); 551 552 /// updateDFSNumbers - Assign In and Out numbers to the nodes while walking 553 /// dominator tree in dfs order. 554 void updateDFSNumbers() { 555 unsigned DFSNum = 0; 556 557 SmallVector<std::pair<DomTreeNodeBase<NodeT>*, 558 typename DomTreeNodeBase<NodeT>::iterator>, 32> WorkStack; 559 560 for (unsigned i = 0, e = this->Roots.size(); i != e; ++i) { 561 DomTreeNodeBase<NodeT> *ThisRoot = getNode(this->Roots[i]); 562 WorkStack.push_back(std::make_pair(ThisRoot, ThisRoot->begin())); 563 ThisRoot->DFSNumIn = DFSNum++; 564 565 while (!WorkStack.empty()) { 566 DomTreeNodeBase<NodeT> *Node = WorkStack.back().first; 567 typename DomTreeNodeBase<NodeT>::iterator ChildIt = 568 WorkStack.back().second; 569 570 // If we visited all of the children of this node, "recurse" back up the 571 // stack setting the DFOutNum. 572 if (ChildIt == Node->end()) { 573 Node->DFSNumOut = DFSNum++; 574 WorkStack.pop_back(); 575 } else { 576 // Otherwise, recursively visit this child. 577 DomTreeNodeBase<NodeT> *Child = *ChildIt; 578 ++WorkStack.back().second; 579 580 WorkStack.push_back(std::make_pair(Child, Child->begin())); 581 Child->DFSNumIn = DFSNum++; 582 } 583 } 584 } 585 586 SlowQueries = 0; 587 DFSInfoValid = true; 588 } 589 590 DomTreeNodeBase<NodeT> *getNodeForBlock(NodeT *BB) { 591 if (DomTreeNodeBase<NodeT> *BBNode = this->DomTreeNodes[BB]) 592 return BBNode; 593 594 // Haven't calculated this node yet? Get or calculate the node for the 595 // immediate dominator. 596 NodeT *IDom = getIDom(BB); 597 DomTreeNodeBase<NodeT> *IDomNode = getNodeForBlock(IDom); 598 599 // Add a new tree node for this BasicBlock, and link it as a child of 600 // IDomNode 601 DomTreeNodeBase<NodeT> *C = new DomTreeNodeBase<NodeT>(BB, IDomNode); 602 return this->DomTreeNodes[BB] = IDomNode->addChild(C); 603 } 604 605 inline NodeT *getIDom(NodeT *BB) const { 606 typename DenseMap<NodeT*, NodeT*>::const_iterator I = IDoms.find(BB); 607 return I != IDoms.end() ? I->second : 0; 608 } 609 610 inline void addRoot(NodeT* BB) { 611 // Unreachable block is not a root node. 612 if (!isa<UnreachableInst>(&BB->back())) 613 this->Roots.push_back(BB); 614 } 615 616public: 617 /// recalculate - compute a dominator tree for the given function 618 template<class FT> 619 void recalculate(FT& F) { 620 if (!this->IsPostDominators) { 621 reset(); 622 623 // Initialize roots 624 this->Roots.push_back(&F.front()); 625 this->IDoms[&F.front()] = 0; 626 this->DomTreeNodes[&F.front()] = 0; 627 this->Vertex.push_back(0); 628 629 Calculate<FT, NodeT*>(*this, F); 630 631 updateDFSNumbers(); 632 } else { 633 reset(); // Reset from the last time we were run... 634 635 // Initialize the roots list 636 for (typename FT::iterator I = F.begin(), E = F.end(); I != E; ++I) { 637 if (std::distance(GraphTraits<FT*>::child_begin(I), 638 GraphTraits<FT*>::child_end(I)) == 0) 639 addRoot(I); 640 641 // Prepopulate maps so that we don't get iterator invalidation issues later. 642 this->IDoms[I] = 0; 643 this->DomTreeNodes[I] = 0; 644 } 645 646 this->Vertex.push_back(0); 647 648 Calculate<FT, Inverse<NodeT*> >(*this, F); 649 } 650 } 651}; 652 653EXTERN_TEMPLATE_INSTANTIATION(class DominatorTreeBase<BasicBlock>); 654 655//===------------------------------------- 656/// DominatorTree Class - Concrete subclass of DominatorTreeBase that is used to 657/// compute a normal dominator tree. 658/// 659class DominatorTree : public FunctionPass { 660public: 661 static char ID; // Pass ID, replacement for typeid 662 DominatorTreeBase<BasicBlock>* DT; 663 664 DominatorTree() : FunctionPass(intptr_t(&ID)) { 665 DT = new DominatorTreeBase<BasicBlock>(false); 666 } 667 668 ~DominatorTree() { 669 DT->releaseMemory(); 670 delete DT; 671 } 672 673 /// getRoots - Return the root blocks of the current CFG. This may include 674 /// multiple blocks if we are computing post dominators. For forward 675 /// dominators, this will always be a single block (the entry node). 676 /// 677 inline const std::vector<BasicBlock*> &getRoots() const { 678 return DT->getRoots(); 679 } 680 681 inline BasicBlock *getRoot() const { 682 return DT->getRoot(); 683 } 684 685 inline DomTreeNode *getRootNode() const { 686 return DT->getRootNode(); 687 } 688 689 virtual bool runOnFunction(Function &F); 690 691 virtual void getAnalysisUsage(AnalysisUsage &AU) const { 692 AU.setPreservesAll(); 693 } 694 695 inline bool dominates(DomTreeNode* A, DomTreeNode* B) const { 696 return DT->dominates(A, B); 697 } 698 699 inline bool dominates(BasicBlock* A, BasicBlock* B) const { 700 return DT->dominates(A, B); 701 } 702 703 // dominates - Return true if A dominates B. This performs the 704 // special checks necessary if A and B are in the same basic block. 705 bool dominates(Instruction *A, Instruction *B) const { 706 BasicBlock *BBA = A->getParent(), *BBB = B->getParent(); 707 if (BBA != BBB) return DT->dominates(BBA, BBB); 708 709 // It is not possible to determine dominance between two PHI nodes 710 // based on their ordering. 711 if (isa<PHINode>(A) && isa<PHINode>(B)) 712 return false; 713 714 // Loop through the basic block until we find A or B. 715 BasicBlock::iterator I = BBA->begin(); 716 for (; &*I != A && &*I != B; ++I) /*empty*/; 717 718 //if(!DT.IsPostDominators) { 719 // A dominates B if it is found first in the basic block. 720 return &*I == A; 721 //} else { 722 // // A post-dominates B if B is found first in the basic block. 723 // return &*I == B; 724 //} 725 } 726 727 inline bool properlyDominates(const DomTreeNode* A, DomTreeNode* B) const { 728 return DT->properlyDominates(A, B); 729 } 730 731 inline bool properlyDominates(BasicBlock* A, BasicBlock* B) const { 732 return DT->properlyDominates(A, B); 733 } 734 735 /// findNearestCommonDominator - Find nearest common dominator basic block 736 /// for basic block A and B. If there is no such block then return NULL. 737 inline BasicBlock *findNearestCommonDominator(BasicBlock *A, BasicBlock *B) { 738 return DT->findNearestCommonDominator(A, B); 739 } 740 741 inline DomTreeNode *operator[](BasicBlock *BB) const { 742 return DT->getNode(BB); 743 } 744 745 /// getNode - return the (Post)DominatorTree node for the specified basic 746 /// block. This is the same as using operator[] on this class. 747 /// 748 inline DomTreeNode *getNode(BasicBlock *BB) const { 749 return DT->getNode(BB); 750 } 751 752 /// addNewBlock - Add a new node to the dominator tree information. This 753 /// creates a new node as a child of DomBB dominator node,linking it into 754 /// the children list of the immediate dominator. 755 inline DomTreeNode *addNewBlock(BasicBlock *BB, BasicBlock *DomBB) { 756 return DT->addNewBlock(BB, DomBB); 757 } 758 759 /// changeImmediateDominator - This method is used to update the dominator 760 /// tree information when a node's immediate dominator changes. 761 /// 762 inline void changeImmediateDominator(BasicBlock *N, BasicBlock* NewIDom) { 763 DT->changeImmediateDominator(N, NewIDom); 764 } 765 766 inline void changeImmediateDominator(DomTreeNode *N, DomTreeNode* NewIDom) { 767 DT->changeImmediateDominator(N, NewIDom); 768 } 769 770 /// eraseNode - Removes a node from the dominator tree. Block must not 771 /// domiante any other blocks. Removes node from its immediate dominator's 772 /// children list. Deletes dominator node associated with basic block BB. 773 inline void eraseNode(BasicBlock *BB) { 774 DT->eraseNode(BB); 775 } 776 777 /// splitBlock - BB is split and now it has one successor. Update dominator 778 /// tree to reflect this change. 779 inline void splitBlock(BasicBlock* NewBB) { 780 DT->splitBlock(NewBB); 781 } 782 783 784 virtual void releaseMemory() { 785 DT->releaseMemory(); 786 } 787 788 virtual void print(std::ostream &OS, const Module* M= 0) const { 789 DT->print(OS, M); 790 } 791}; 792 793//===------------------------------------- 794/// DominatorTree GraphTraits specialization so the DominatorTree can be 795/// iterable by generic graph iterators. 796/// 797template <> struct GraphTraits<DomTreeNode *> { 798 typedef DomTreeNode NodeType; 799 typedef NodeType::iterator ChildIteratorType; 800 801 static NodeType *getEntryNode(NodeType *N) { 802 return N; 803 } 804 static inline ChildIteratorType child_begin(NodeType* N) { 805 return N->begin(); 806 } 807 static inline ChildIteratorType child_end(NodeType* N) { 808 return N->end(); 809 } 810}; 811 812template <> struct GraphTraits<DominatorTree*> 813 : public GraphTraits<DomTreeNode *> { 814 static NodeType *getEntryNode(DominatorTree *DT) { 815 return DT->getRootNode(); 816 } 817}; 818 819 820//===----------------------------------------------------------------------===// 821/// DominanceFrontierBase - Common base class for computing forward and inverse 822/// dominance frontiers for a function. 823/// 824class DominanceFrontierBase : public FunctionPass { 825public: 826 typedef std::set<BasicBlock*> DomSetType; // Dom set for a bb 827 typedef std::map<BasicBlock*, DomSetType> DomSetMapType; // Dom set map 828protected: 829 DomSetMapType Frontiers; 830 std::vector<BasicBlock*> Roots; 831 const bool IsPostDominators; 832 833public: 834 DominanceFrontierBase(intptr_t ID, bool isPostDom) 835 : FunctionPass(ID), IsPostDominators(isPostDom) {} 836 837 /// getRoots - Return the root blocks of the current CFG. This may include 838 /// multiple blocks if we are computing post dominators. For forward 839 /// dominators, this will always be a single block (the entry node). 840 /// 841 inline const std::vector<BasicBlock*> &getRoots() const { return Roots; } 842 843 /// isPostDominator - Returns true if analysis based of postdoms 844 /// 845 bool isPostDominator() const { return IsPostDominators; } 846 847 virtual void releaseMemory() { Frontiers.clear(); } 848 849 // Accessor interface: 850 typedef DomSetMapType::iterator iterator; 851 typedef DomSetMapType::const_iterator const_iterator; 852 iterator begin() { return Frontiers.begin(); } 853 const_iterator begin() const { return Frontiers.begin(); } 854 iterator end() { return Frontiers.end(); } 855 const_iterator end() const { return Frontiers.end(); } 856 iterator find(BasicBlock *B) { return Frontiers.find(B); } 857 const_iterator find(BasicBlock *B) const { return Frontiers.find(B); } 858 859 void addBasicBlock(BasicBlock *BB, const DomSetType &frontier) { 860 assert(find(BB) == end() && "Block already in DominanceFrontier!"); 861 Frontiers.insert(std::make_pair(BB, frontier)); 862 } 863 864 /// removeBlock - Remove basic block BB's frontier. 865 void removeBlock(BasicBlock *BB) { 866 assert(find(BB) != end() && "Block is not in DominanceFrontier!"); 867 for (iterator I = begin(), E = end(); I != E; ++I) 868 I->second.erase(BB); 869 Frontiers.erase(BB); 870 } 871 872 void addToFrontier(iterator I, BasicBlock *Node) { 873 assert(I != end() && "BB is not in DominanceFrontier!"); 874 I->second.insert(Node); 875 } 876 877 void removeFromFrontier(iterator I, BasicBlock *Node) { 878 assert(I != end() && "BB is not in DominanceFrontier!"); 879 assert(I->second.count(Node) && "Node is not in DominanceFrontier of BB"); 880 I->second.erase(Node); 881 } 882 883 /// print - Convert to human readable form 884 /// 885 virtual void print(std::ostream &OS, const Module* = 0) const; 886 void print(std::ostream *OS, const Module* M = 0) const { 887 if (OS) print(*OS, M); 888 } 889 virtual void dump(); 890}; 891 892 893//===------------------------------------- 894/// DominanceFrontier Class - Concrete subclass of DominanceFrontierBase that is 895/// used to compute a forward dominator frontiers. 896/// 897class DominanceFrontier : public DominanceFrontierBase { 898public: 899 static char ID; // Pass ID, replacement for typeid 900 DominanceFrontier() : 901 DominanceFrontierBase(intptr_t(&ID), false) {} 902 903 BasicBlock *getRoot() const { 904 assert(Roots.size() == 1 && "Should always have entry node!"); 905 return Roots[0]; 906 } 907 908 virtual bool runOnFunction(Function &) { 909 Frontiers.clear(); 910 DominatorTree &DT = getAnalysis<DominatorTree>(); 911 Roots = DT.getRoots(); 912 assert(Roots.size() == 1 && "Only one entry block for forward domfronts!"); 913 calculate(DT, DT[Roots[0]]); 914 return false; 915 } 916 917 virtual void getAnalysisUsage(AnalysisUsage &AU) const { 918 AU.setPreservesAll(); 919 AU.addRequired<DominatorTree>(); 920 } 921 922 /// splitBlock - BB is split and now it has one successor. Update dominance 923 /// frontier to reflect this change. 924 void splitBlock(BasicBlock *BB); 925 926 /// BasicBlock BB's new dominator is NewBB. Update BB's dominance frontier 927 /// to reflect this change. 928 void changeImmediateDominator(BasicBlock *BB, BasicBlock *NewBB, 929 DominatorTree *DT) { 930 // NewBB is now dominating BB. Which means BB's dominance 931 // frontier is now part of NewBB's dominance frontier. However, BB 932 // itself is not member of NewBB's dominance frontier. 933 DominanceFrontier::iterator NewDFI = find(NewBB); 934 DominanceFrontier::iterator DFI = find(BB); 935 DominanceFrontier::DomSetType BBSet = DFI->second; 936 for (DominanceFrontier::DomSetType::iterator BBSetI = BBSet.begin(), 937 BBSetE = BBSet.end(); BBSetI != BBSetE; ++BBSetI) { 938 BasicBlock *DFMember = *BBSetI; 939 // Insert only if NewBB dominates DFMember. 940 if (!DT->dominates(NewBB, DFMember)) 941 NewDFI->second.insert(DFMember); 942 } 943 NewDFI->second.erase(BB); 944 } 945 946private: 947 const DomSetType &calculate(const DominatorTree &DT, 948 const DomTreeNode *Node); 949}; 950 951 952} // End llvm namespace 953 954#endif 955