1 //===- llvm/Analysis/Dominators.h - Dominator Info Calculation --*- C++ -*-===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
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
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.
19 //===----------------------------------------------------------------------===//
21 #ifndef LLVM_ANALYSIS_DOMINATORS_H
22 #define LLVM_ANALYSIS_DOMINATORS_H
24 #include "llvm/Pass.h"
25 #include "llvm/BasicBlock.h"
26 #include "llvm/Function.h"
27 #include "llvm/Instructions.h"
28 #include "llvm/ADT/DenseMap.h"
29 #include "llvm/ADT/GraphTraits.h"
30 #include "llvm/ADT/SmallPtrSet.h"
31 #include "llvm/ADT/SmallVector.h"
32 #include "llvm/Assembly/Writer.h"
33 #include "llvm/Support/CFG.h"
34 #include "llvm/Support/Compiler.h"
41 //===----------------------------------------------------------------------===//
42 /// DominatorBase - Base class that other, more interesting dominator analyses
45 template <class NodeT>
48 std::vector<NodeT*> Roots;
49 const bool IsPostDominators;
50 inline explicit DominatorBase(bool isPostDom) :
51 Roots(), IsPostDominators(isPostDom) {}
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).
58 inline const std::vector<NodeT*> &getRoots() const { return Roots; }
60 /// isPostDominator - Returns true if analysis based of postdoms
62 bool isPostDominator() const { return IsPostDominators; }
66 //===----------------------------------------------------------------------===//
67 // DomTreeNode - Dominator Tree Node
68 template<class NodeT> class DominatorTreeBase;
69 struct PostDominatorTree;
70 class MachineBasicBlock;
72 template <class NodeT>
73 class DomTreeNodeBase {
75 DomTreeNodeBase<NodeT> *IDom;
76 std::vector<DomTreeNodeBase<NodeT> *> Children;
77 int DFSNumIn, DFSNumOut;
79 template<class N> friend class DominatorTreeBase;
80 friend struct PostDominatorTree;
82 typedef typename std::vector<DomTreeNodeBase<NodeT> *>::iterator iterator;
83 typedef typename std::vector<DomTreeNodeBase<NodeT> *>::const_iterator
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(); }
91 NodeT *getBlock() const { return TheBB; }
92 DomTreeNodeBase<NodeT> *getIDom() const { return IDom; }
93 const std::vector<DomTreeNodeBase<NodeT>*> &getChildren() const {
97 DomTreeNodeBase(NodeT *BB, DomTreeNodeBase<NodeT> *iDom)
98 : TheBB(BB), IDom(iDom), DFSNumIn(-1), DFSNumOut(-1) { }
100 DomTreeNodeBase<NodeT> *addChild(DomTreeNodeBase<NodeT> *C) {
101 Children.push_back(C);
105 size_t getNumChildren() const {
106 return Children.size();
109 void clearAllChildren() {
113 bool compare(DomTreeNodeBase<NodeT> *Other) {
114 if (getNumChildren() != Other->getNumChildren())
117 SmallPtrSet<NodeT *, 4> OtherChildren;
118 for(iterator I = Other->begin(), E = Other->end(); I != E; ++I) {
119 NodeT *Nd = (*I)->getBlock();
120 OtherChildren.insert(Nd);
123 for(iterator I = begin(), E = end(); I != E; ++I) {
124 NodeT *N = (*I)->getBlock();
125 if (OtherChildren.count(N) == 0)
131 void setIDom(DomTreeNodeBase<NodeT> *NewIDom) {
132 assert(IDom && "No immediate dominator?");
133 if (IDom != NewIDom) {
134 typename std::vector<DomTreeNodeBase<NodeT>*>::iterator I =
135 std::find(IDom->Children.begin(), IDom->Children.end(), this);
136 assert(I != IDom->Children.end() &&
137 "Not in immediate dominator children set!");
138 // I am no longer your child...
139 IDom->Children.erase(I);
141 // Switch to new dominator
143 IDom->Children.push_back(this);
147 /// getDFSNumIn/getDFSNumOut - These are an internal implementation detail, do
149 unsigned getDFSNumIn() const { return DFSNumIn; }
150 unsigned getDFSNumOut() const { return DFSNumOut; }
152 // Return true if this node is dominated by other. Use this only if DFS info
154 bool DominatedBy(const DomTreeNodeBase<NodeT> *other) const {
155 return this->DFSNumIn >= other->DFSNumIn &&
156 this->DFSNumOut <= other->DFSNumOut;
160 EXTERN_TEMPLATE_INSTANTIATION(class DomTreeNodeBase<BasicBlock>);
161 EXTERN_TEMPLATE_INSTANTIATION(class DomTreeNodeBase<MachineBasicBlock>);
163 template<class NodeT>
164 static std::ostream &operator<<(std::ostream &o,
165 const DomTreeNodeBase<NodeT> *Node) {
166 if (Node->getBlock())
167 WriteAsOperand(o, Node->getBlock(), false);
169 o << " <<exit node>>";
171 o << " {" << Node->getDFSNumIn() << "," << Node->getDFSNumOut() << "}";
176 template<class NodeT>
177 static void PrintDomTree(const DomTreeNodeBase<NodeT> *N, std::ostream &o,
179 o << std::string(2*Lev, ' ') << "[" << Lev << "] " << N;
180 for (typename DomTreeNodeBase<NodeT>::const_iterator I = N->begin(),
181 E = N->end(); I != E; ++I)
182 PrintDomTree<NodeT>(*I, o, Lev+1);
185 typedef DomTreeNodeBase<BasicBlock> DomTreeNode;
187 //===----------------------------------------------------------------------===//
188 /// DominatorTree - Calculate the immediate dominator tree for a function.
191 template<class FuncT, class N>
192 void Calculate(DominatorTreeBase<typename GraphTraits<N>::NodeType>& DT,
195 template<class NodeT>
196 class DominatorTreeBase : public DominatorBase<NodeT> {
198 typedef DenseMap<NodeT*, DomTreeNodeBase<NodeT>*> DomTreeNodeMapType;
199 DomTreeNodeMapType DomTreeNodes;
200 DomTreeNodeBase<NodeT> *RootNode;
203 unsigned int SlowQueries;
204 // Information record used during immediate dominators computation.
209 NodeT *Label, *Child;
210 unsigned Parent, Ancestor;
212 std::vector<NodeT*> Bucket;
214 InfoRec() : DFSNum(0), Semi(0), Size(0), Label(0), Child(0), Parent(0),
218 DenseMap<NodeT*, NodeT*> IDoms;
220 // Vertex - Map the DFS number to the BasicBlock*
221 std::vector<NodeT*> Vertex;
223 // Info - Collection of information used during the computation of idoms.
224 DenseMap<NodeT*, InfoRec> Info;
227 for (typename DomTreeNodeMapType::iterator I = this->DomTreeNodes.begin(),
228 E = DomTreeNodes.end(); I != E; ++I)
230 DomTreeNodes.clear();
237 // NewBB is split and now it has one successor. Update dominator tree to
238 // reflect this change.
239 template<class N, class GraphT>
240 void Split(DominatorTreeBase<typename GraphT::NodeType>& DT,
241 typename GraphT::NodeType* NewBB) {
242 assert(std::distance(GraphT::child_begin(NewBB), GraphT::child_end(NewBB)) == 1
243 && "NewBB should have a single successor!");
244 typename GraphT::NodeType* NewBBSucc = *GraphT::child_begin(NewBB);
246 std::vector<typename GraphT::NodeType*> PredBlocks;
247 for (typename GraphTraits<Inverse<N> >::ChildIteratorType PI =
248 GraphTraits<Inverse<N> >::child_begin(NewBB),
249 PE = GraphTraits<Inverse<N> >::child_end(NewBB); PI != PE; ++PI)
250 PredBlocks.push_back(*PI);
252 assert(!PredBlocks.empty() && "No predblocks??");
254 // The newly inserted basic block will dominate existing basic blocks iff the
255 // PredBlocks dominate all of the non-pred blocks. If all predblocks dominate
256 // the non-pred blocks, then they all must be the same block!
258 bool NewBBDominatesNewBBSucc = true;
260 typename GraphT::NodeType* OnePred = PredBlocks[0];
261 size_t i = 1, e = PredBlocks.size();
262 for (i = 1; !DT.isReachableFromEntry(OnePred); ++i) {
263 assert(i != e && "Didn't find reachable pred?");
264 OnePred = PredBlocks[i];
268 if (PredBlocks[i] != OnePred && DT.isReachableFromEntry(OnePred)) {
269 NewBBDominatesNewBBSucc = false;
273 if (NewBBDominatesNewBBSucc)
274 for (typename GraphTraits<Inverse<N> >::ChildIteratorType PI =
275 GraphTraits<Inverse<N> >::child_begin(NewBBSucc),
276 E = GraphTraits<Inverse<N> >::child_end(NewBBSucc); PI != E; ++PI)
277 if (*PI != NewBB && !DT.dominates(NewBBSucc, *PI)) {
278 NewBBDominatesNewBBSucc = false;
283 // The other scenario where the new block can dominate its successors are when
284 // all predecessors of NewBBSucc that are not NewBB are dominated by NewBBSucc
286 if (!NewBBDominatesNewBBSucc) {
287 NewBBDominatesNewBBSucc = true;
288 for (typename GraphTraits<Inverse<N> >::ChildIteratorType PI =
289 GraphTraits<Inverse<N> >::child_begin(NewBBSucc),
290 E = GraphTraits<Inverse<N> >::child_end(NewBBSucc); PI != E; ++PI)
291 if (*PI != NewBB && !DT.dominates(NewBBSucc, *PI)) {
292 NewBBDominatesNewBBSucc = false;
297 // Find NewBB's immediate dominator and create new dominator tree node for
299 NodeT *NewBBIDom = 0;
301 for (i = 0; i < PredBlocks.size(); ++i)
302 if (DT.isReachableFromEntry(PredBlocks[i])) {
303 NewBBIDom = PredBlocks[i];
306 assert(i != PredBlocks.size() && "No reachable preds?");
307 for (i = i + 1; i < PredBlocks.size(); ++i) {
308 if (DT.isReachableFromEntry(PredBlocks[i]))
309 NewBBIDom = DT.findNearestCommonDominator(NewBBIDom, PredBlocks[i]);
311 assert(NewBBIDom && "No immediate dominator found??");
313 // Create the new dominator tree node... and set the idom of NewBB.
314 DomTreeNodeBase<NodeT> *NewBBNode = DT.addNewBlock(NewBB, NewBBIDom);
316 // If NewBB strictly dominates other blocks, then it is now the immediate
317 // dominator of NewBBSucc. Update the dominator tree as appropriate.
318 if (NewBBDominatesNewBBSucc) {
319 DomTreeNodeBase<NodeT> *NewBBSuccNode = DT.getNode(NewBBSucc);
320 DT.changeImmediateDominator(NewBBSuccNode, NewBBNode);
325 explicit DominatorTreeBase(bool isPostDom)
326 : DominatorBase<NodeT>(isPostDom), DFSInfoValid(false), SlowQueries(0) {}
327 virtual ~DominatorTreeBase() { reset(); }
329 // FIXME: Should remove this
330 virtual bool runOnFunction(Function &F) { return false; }
332 /// compare - Return false if the other dominator tree base matches this
333 /// dominator tree base. Otherwise return true.
334 bool compare(DominatorTreeBase &Other) const {
336 const DomTreeNodeMapType &OtherDomTreeNodes = Other.DomTreeNodes;
337 if (DomTreeNodes.size() != OtherDomTreeNodes.size())
340 SmallPtrSet<const NodeT *,4> MyBBs;
341 for (typename DomTreeNodeMapType::const_iterator
342 I = this->DomTreeNodes.begin(),
343 E = this->DomTreeNodes.end(); I != E; ++I) {
344 NodeT *BB = I->first;
345 typename DomTreeNodeMapType::const_iterator OI = OtherDomTreeNodes.find(BB);
346 if (OI == OtherDomTreeNodes.end())
349 DomTreeNodeBase<NodeT>* MyNd = I->second;
350 DomTreeNodeBase<NodeT>* OtherNd = OI->second;
352 if (MyNd->compare(OtherNd))
359 virtual void releaseMemory() { reset(); }
361 /// getNode - return the (Post)DominatorTree node for the specified basic
362 /// block. This is the same as using operator[] on this class.
364 inline DomTreeNodeBase<NodeT> *getNode(NodeT *BB) const {
365 typename DomTreeNodeMapType::const_iterator I = DomTreeNodes.find(BB);
366 return I != DomTreeNodes.end() ? I->second : 0;
369 /// getRootNode - This returns the entry node for the CFG of the function. If
370 /// this tree represents the post-dominance relations for a function, however,
371 /// this root may be a node with the block == NULL. This is the case when
372 /// there are multiple exit nodes from a particular function. Consumers of
373 /// post-dominance information must be capable of dealing with this
376 DomTreeNodeBase<NodeT> *getRootNode() { return RootNode; }
377 const DomTreeNodeBase<NodeT> *getRootNode() const { return RootNode; }
379 /// properlyDominates - Returns true iff this dominates N and this != N.
380 /// Note that this is not a constant time operation!
382 bool properlyDominates(const DomTreeNodeBase<NodeT> *A,
383 DomTreeNodeBase<NodeT> *B) const {
384 if (A == 0 || B == 0) return false;
385 return dominatedBySlowTreeWalk(A, B);
388 inline bool properlyDominates(NodeT *A, NodeT *B) {
389 return properlyDominates(getNode(A), getNode(B));
392 bool dominatedBySlowTreeWalk(const DomTreeNodeBase<NodeT> *A,
393 const DomTreeNodeBase<NodeT> *B) const {
394 const DomTreeNodeBase<NodeT> *IDom;
395 if (A == 0 || B == 0) return false;
396 while ((IDom = B->getIDom()) != 0 && IDom != A && IDom != B)
397 B = IDom; // Walk up the tree
402 /// isReachableFromEntry - Return true if A is dominated by the entry
403 /// block of the function containing it.
404 bool isReachableFromEntry(NodeT* A) {
405 assert (!this->isPostDominator()
406 && "This is not implemented for post dominators");
407 return dominates(&A->getParent()->front(), A);
410 /// dominates - Returns true iff A dominates B. Note that this is not a
411 /// constant time operation!
413 inline bool dominates(const DomTreeNodeBase<NodeT> *A,
414 DomTreeNodeBase<NodeT> *B) {
416 return true; // A node trivially dominates itself.
418 if (A == 0 || B == 0)
422 return B->DominatedBy(A);
424 // If we end up with too many slow queries, just update the
425 // DFS numbers on the theory that we are going to keep querying.
427 if (SlowQueries > 32) {
429 return B->DominatedBy(A);
432 return dominatedBySlowTreeWalk(A, B);
435 inline bool dominates(NodeT *A, NodeT *B) {
439 return dominates(getNode(A), getNode(B));
442 NodeT *getRoot() const {
443 assert(this->Roots.size() == 1 && "Should always have entry node!");
444 return this->Roots[0];
447 /// findNearestCommonDominator - Find nearest common dominator basic block
448 /// for basic block A and B. If there is no such block then return NULL.
449 NodeT *findNearestCommonDominator(NodeT *A, NodeT *B) {
451 assert (!this->isPostDominator()
452 && "This is not implemented for post dominators");
453 assert (A->getParent() == B->getParent()
454 && "Two blocks are not in same function");
456 // If either A or B is a entry block then it is nearest common dominator.
457 NodeT &Entry = A->getParent()->front();
458 if (A == &Entry || B == &Entry)
461 // If B dominates A then B is nearest common dominator.
465 // If A dominates B then A is nearest common dominator.
469 DomTreeNodeBase<NodeT> *NodeA = getNode(A);
470 DomTreeNodeBase<NodeT> *NodeB = getNode(B);
472 // Collect NodeA dominators set.
473 SmallPtrSet<DomTreeNodeBase<NodeT>*, 16> NodeADoms;
474 NodeADoms.insert(NodeA);
475 DomTreeNodeBase<NodeT> *IDomA = NodeA->getIDom();
477 NodeADoms.insert(IDomA);
478 IDomA = IDomA->getIDom();
481 // Walk NodeB immediate dominators chain and find common dominator node.
482 DomTreeNodeBase<NodeT> *IDomB = NodeB->getIDom();
484 if (NodeADoms.count(IDomB) != 0)
485 return IDomB->getBlock();
487 IDomB = IDomB->getIDom();
493 //===--------------------------------------------------------------------===//
494 // API to update (Post)DominatorTree information based on modifications to
497 /// addNewBlock - Add a new node to the dominator tree information. This
498 /// creates a new node as a child of DomBB dominator node,linking it into
499 /// the children list of the immediate dominator.
500 DomTreeNodeBase<NodeT> *addNewBlock(NodeT *BB, NodeT *DomBB) {
501 assert(getNode(BB) == 0 && "Block already in dominator tree!");
502 DomTreeNodeBase<NodeT> *IDomNode = getNode(DomBB);
503 assert(IDomNode && "Not immediate dominator specified for block!");
504 DFSInfoValid = false;
505 return DomTreeNodes[BB] =
506 IDomNode->addChild(new DomTreeNodeBase<NodeT>(BB, IDomNode));
509 /// changeImmediateDominator - This method is used to update the dominator
510 /// tree information when a node's immediate dominator changes.
512 void changeImmediateDominator(DomTreeNodeBase<NodeT> *N,
513 DomTreeNodeBase<NodeT> *NewIDom) {
514 assert(N && NewIDom && "Cannot change null node pointers!");
515 DFSInfoValid = false;
519 void changeImmediateDominator(NodeT *BB, NodeT *NewBB) {
520 changeImmediateDominator(getNode(BB), getNode(NewBB));
523 /// eraseNode - Removes a node from the dominator tree. Block must not
524 /// domiante any other blocks. Removes node from its immediate dominator's
525 /// children list. Deletes dominator node associated with basic block BB.
526 void eraseNode(NodeT *BB) {
527 DomTreeNodeBase<NodeT> *Node = getNode(BB);
528 assert (Node && "Removing node that isn't in dominator tree.");
529 assert (Node->getChildren().empty() && "Node is not a leaf node.");
531 // Remove node from immediate dominator's children list.
532 DomTreeNodeBase<NodeT> *IDom = Node->getIDom();
534 typename std::vector<DomTreeNodeBase<NodeT>*>::iterator I =
535 std::find(IDom->Children.begin(), IDom->Children.end(), Node);
536 assert(I != IDom->Children.end() &&
537 "Not in immediate dominator children set!");
538 // I am no longer your child...
539 IDom->Children.erase(I);
542 DomTreeNodes.erase(BB);
546 /// removeNode - Removes a node from the dominator tree. Block must not
547 /// dominate any other blocks. Invalidates any node pointing to removed
549 void removeNode(NodeT *BB) {
550 assert(getNode(BB) && "Removing node that isn't in dominator tree.");
551 DomTreeNodes.erase(BB);
554 /// splitBlock - BB is split and now it has one successor. Update dominator
555 /// tree to reflect this change.
556 void splitBlock(NodeT* NewBB) {
557 if (this->IsPostDominators)
558 this->Split<Inverse<NodeT*>, GraphTraits<Inverse<NodeT*> > >(*this, NewBB);
560 this->Split<NodeT*, GraphTraits<NodeT*> >(*this, NewBB);
563 /// print - Convert to human readable form
565 virtual void print(std::ostream &o, const Module* ) const {
566 o << "=============================--------------------------------\n";
567 if (this->isPostDominator())
568 o << "Inorder PostDominator Tree: ";
570 o << "Inorder Dominator Tree: ";
571 if (this->DFSInfoValid)
572 o << "DFSNumbers invalid: " << SlowQueries << " slow queries.";
575 PrintDomTree<NodeT>(getRootNode(), o, 1);
578 void print(std::ostream *OS, const Module* M = 0) const {
579 if (OS) print(*OS, M);
582 virtual void dump() {
587 template<class GraphT>
588 friend void Compress(DominatorTreeBase<typename GraphT::NodeType>& DT,
589 typename GraphT::NodeType* VIn);
591 template<class GraphT>
592 friend typename GraphT::NodeType* Eval(
593 DominatorTreeBase<typename GraphT::NodeType>& DT,
594 typename GraphT::NodeType* V);
596 template<class GraphT>
597 friend void Link(DominatorTreeBase<typename GraphT::NodeType>& DT,
598 unsigned DFSNumV, typename GraphT::NodeType* W,
599 typename DominatorTreeBase<typename GraphT::NodeType>::InfoRec &WInfo);
601 template<class GraphT>
602 friend unsigned DFSPass(DominatorTreeBase<typename GraphT::NodeType>& DT,
603 typename GraphT::NodeType* V,
606 template<class FuncT, class N>
607 friend void Calculate(DominatorTreeBase<typename GraphTraits<N>::NodeType>& DT,
610 /// updateDFSNumbers - Assign In and Out numbers to the nodes while walking
611 /// dominator tree in dfs order.
612 void updateDFSNumbers() {
615 SmallVector<std::pair<DomTreeNodeBase<NodeT>*,
616 typename DomTreeNodeBase<NodeT>::iterator>, 32> WorkStack;
618 for (unsigned i = 0, e = (unsigned)this->Roots.size(); i != e; ++i) {
619 DomTreeNodeBase<NodeT> *ThisRoot = getNode(this->Roots[i]);
620 WorkStack.push_back(std::make_pair(ThisRoot, ThisRoot->begin()));
621 ThisRoot->DFSNumIn = DFSNum++;
623 while (!WorkStack.empty()) {
624 DomTreeNodeBase<NodeT> *Node = WorkStack.back().first;
625 typename DomTreeNodeBase<NodeT>::iterator ChildIt =
626 WorkStack.back().second;
628 // If we visited all of the children of this node, "recurse" back up the
629 // stack setting the DFOutNum.
630 if (ChildIt == Node->end()) {
631 Node->DFSNumOut = DFSNum++;
632 WorkStack.pop_back();
634 // Otherwise, recursively visit this child.
635 DomTreeNodeBase<NodeT> *Child = *ChildIt;
636 ++WorkStack.back().second;
638 WorkStack.push_back(std::make_pair(Child, Child->begin()));
639 Child->DFSNumIn = DFSNum++;
648 DomTreeNodeBase<NodeT> *getNodeForBlock(NodeT *BB) {
649 if (DomTreeNodeBase<NodeT> *BBNode = this->DomTreeNodes[BB])
652 // Haven't calculated this node yet? Get or calculate the node for the
653 // immediate dominator.
654 NodeT *IDom = getIDom(BB);
656 assert(IDom || this->DomTreeNodes[NULL]);
657 DomTreeNodeBase<NodeT> *IDomNode = getNodeForBlock(IDom);
659 // Add a new tree node for this BasicBlock, and link it as a child of
661 DomTreeNodeBase<NodeT> *C = new DomTreeNodeBase<NodeT>(BB, IDomNode);
662 return this->DomTreeNodes[BB] = IDomNode->addChild(C);
665 inline NodeT *getIDom(NodeT *BB) const {
666 typename DenseMap<NodeT*, NodeT*>::const_iterator I = IDoms.find(BB);
667 return I != IDoms.end() ? I->second : 0;
670 inline void addRoot(NodeT* BB) {
671 this->Roots.push_back(BB);
675 /// recalculate - compute a dominator tree for the given function
677 void recalculate(FT& F) {
678 if (!this->IsPostDominators) {
682 this->Roots.push_back(&F.front());
683 this->IDoms[&F.front()] = 0;
684 this->DomTreeNodes[&F.front()] = 0;
685 this->Vertex.push_back(0);
687 Calculate<FT, NodeT*>(*this, F);
691 reset(); // Reset from the last time we were run...
693 // Initialize the roots list
694 for (typename FT::iterator I = F.begin(), E = F.end(); I != E; ++I) {
695 if (std::distance(GraphTraits<FT*>::child_begin(I),
696 GraphTraits<FT*>::child_end(I)) == 0)
699 // Prepopulate maps so that we don't get iterator invalidation issues later.
701 this->DomTreeNodes[I] = 0;
704 this->Vertex.push_back(0);
706 Calculate<FT, Inverse<NodeT*> >(*this, F);
711 EXTERN_TEMPLATE_INSTANTIATION(class DominatorTreeBase<BasicBlock>);
713 //===-------------------------------------
714 /// DominatorTree Class - Concrete subclass of DominatorTreeBase that is used to
715 /// compute a normal dominator tree.
717 class DominatorTree : public FunctionPass {
719 static char ID; // Pass ID, replacement for typeid
720 DominatorTreeBase<BasicBlock>* DT;
722 DominatorTree() : FunctionPass(&ID) {
723 DT = new DominatorTreeBase<BasicBlock>(false);
731 DominatorTreeBase<BasicBlock>& getBase() { return *DT; }
733 /// getRoots - Return the root blocks of the current CFG. This may include
734 /// multiple blocks if we are computing post dominators. For forward
735 /// dominators, this will always be a single block (the entry node).
737 inline const std::vector<BasicBlock*> &getRoots() const {
738 return DT->getRoots();
741 inline BasicBlock *getRoot() const {
742 return DT->getRoot();
745 inline DomTreeNode *getRootNode() const {
746 return DT->getRootNode();
749 /// compare - Return false if the other dominator tree matches this
750 /// dominator tree. Otherwise return true.
751 inline bool compare(DominatorTree &Other) const {
752 DomTreeNode *R = getRootNode();
753 DomTreeNode *OtherR = Other.getRootNode();
755 if (!R || !OtherR || R->getBlock() != OtherR->getBlock())
758 if (DT->compare(Other.getBase()))
764 virtual bool runOnFunction(Function &F);
766 virtual void getAnalysisUsage(AnalysisUsage &AU) const {
767 AU.setPreservesAll();
770 inline bool dominates(DomTreeNode* A, DomTreeNode* B) const {
771 return DT->dominates(A, B);
774 inline bool dominates(BasicBlock* A, BasicBlock* B) const {
775 return DT->dominates(A, B);
778 // dominates - Return true if A dominates B. This performs the
779 // special checks necessary if A and B are in the same basic block.
780 bool dominates(Instruction *A, Instruction *B) const {
781 BasicBlock *BBA = A->getParent(), *BBB = B->getParent();
782 if (BBA != BBB) return DT->dominates(BBA, BBB);
784 // It is not possible to determine dominance between two PHI nodes
785 // based on their ordering.
786 if (isa<PHINode>(A) && isa<PHINode>(B))
789 // Loop through the basic block until we find A or B.
790 BasicBlock::iterator I = BBA->begin();
791 for (; &*I != A && &*I != B; ++I) /*empty*/;
793 //if(!DT.IsPostDominators) {
794 // A dominates B if it is found first in the basic block.
797 // // A post-dominates B if B is found first in the basic block.
802 inline bool properlyDominates(const DomTreeNode* A, DomTreeNode* B) const {
803 return DT->properlyDominates(A, B);
806 inline bool properlyDominates(BasicBlock* A, BasicBlock* B) const {
807 return DT->properlyDominates(A, B);
810 /// findNearestCommonDominator - Find nearest common dominator basic block
811 /// for basic block A and B. If there is no such block then return NULL.
812 inline BasicBlock *findNearestCommonDominator(BasicBlock *A, BasicBlock *B) {
813 return DT->findNearestCommonDominator(A, B);
816 inline DomTreeNode *operator[](BasicBlock *BB) const {
817 return DT->getNode(BB);
820 /// getNode - return the (Post)DominatorTree node for the specified basic
821 /// block. This is the same as using operator[] on this class.
823 inline DomTreeNode *getNode(BasicBlock *BB) const {
824 return DT->getNode(BB);
827 /// addNewBlock - Add a new node to the dominator tree information. This
828 /// creates a new node as a child of DomBB dominator node,linking it into
829 /// the children list of the immediate dominator.
830 inline DomTreeNode *addNewBlock(BasicBlock *BB, BasicBlock *DomBB) {
831 return DT->addNewBlock(BB, DomBB);
834 /// changeImmediateDominator - This method is used to update the dominator
835 /// tree information when a node's immediate dominator changes.
837 inline void changeImmediateDominator(BasicBlock *N, BasicBlock* NewIDom) {
838 DT->changeImmediateDominator(N, NewIDom);
841 inline void changeImmediateDominator(DomTreeNode *N, DomTreeNode* NewIDom) {
842 DT->changeImmediateDominator(N, NewIDom);
845 /// eraseNode - Removes a node from the dominator tree. Block must not
846 /// domiante any other blocks. Removes node from its immediate dominator's
847 /// children list. Deletes dominator node associated with basic block BB.
848 inline void eraseNode(BasicBlock *BB) {
852 /// splitBlock - BB is split and now it has one successor. Update dominator
853 /// tree to reflect this change.
854 inline void splitBlock(BasicBlock* NewBB) {
855 DT->splitBlock(NewBB);
858 bool isReachableFromEntry(BasicBlock* A) {
859 return DT->isReachableFromEntry(A);
863 virtual void releaseMemory() {
867 virtual void print(std::ostream &OS, const Module* M= 0) const {
872 //===-------------------------------------
873 /// DominatorTree GraphTraits specialization so the DominatorTree can be
874 /// iterable by generic graph iterators.
876 template <> struct GraphTraits<DomTreeNode *> {
877 typedef DomTreeNode NodeType;
878 typedef NodeType::iterator ChildIteratorType;
880 static NodeType *getEntryNode(NodeType *N) {
883 static inline ChildIteratorType child_begin(NodeType* N) {
886 static inline ChildIteratorType child_end(NodeType* N) {
891 template <> struct GraphTraits<DominatorTree*>
892 : public GraphTraits<DomTreeNode *> {
893 static NodeType *getEntryNode(DominatorTree *DT) {
894 return DT->getRootNode();
899 //===----------------------------------------------------------------------===//
900 /// DominanceFrontierBase - Common base class for computing forward and inverse
901 /// dominance frontiers for a function.
903 class DominanceFrontierBase : public FunctionPass {
905 typedef std::set<BasicBlock*> DomSetType; // Dom set for a bb
906 typedef std::map<BasicBlock*, DomSetType> DomSetMapType; // Dom set map
908 DomSetMapType Frontiers;
909 std::vector<BasicBlock*> Roots;
910 const bool IsPostDominators;
913 DominanceFrontierBase(void *ID, bool isPostDom)
914 : FunctionPass(ID), IsPostDominators(isPostDom) {}
916 /// getRoots - Return the root blocks of the current CFG. This may include
917 /// multiple blocks if we are computing post dominators. For forward
918 /// dominators, this will always be a single block (the entry node).
920 inline const std::vector<BasicBlock*> &getRoots() const { return Roots; }
922 /// isPostDominator - Returns true if analysis based of postdoms
924 bool isPostDominator() const { return IsPostDominators; }
926 virtual void releaseMemory() { Frontiers.clear(); }
928 // Accessor interface:
929 typedef DomSetMapType::iterator iterator;
930 typedef DomSetMapType::const_iterator const_iterator;
931 iterator begin() { return Frontiers.begin(); }
932 const_iterator begin() const { return Frontiers.begin(); }
933 iterator end() { return Frontiers.end(); }
934 const_iterator end() const { return Frontiers.end(); }
935 iterator find(BasicBlock *B) { return Frontiers.find(B); }
936 const_iterator find(BasicBlock *B) const { return Frontiers.find(B); }
938 void addBasicBlock(BasicBlock *BB, const DomSetType &frontier) {
939 assert(find(BB) == end() && "Block already in DominanceFrontier!");
940 Frontiers.insert(std::make_pair(BB, frontier));
943 /// removeBlock - Remove basic block BB's frontier.
944 void removeBlock(BasicBlock *BB) {
945 assert(find(BB) != end() && "Block is not in DominanceFrontier!");
946 for (iterator I = begin(), E = end(); I != E; ++I)
951 void addToFrontier(iterator I, BasicBlock *Node) {
952 assert(I != end() && "BB is not in DominanceFrontier!");
953 I->second.insert(Node);
956 void removeFromFrontier(iterator I, BasicBlock *Node) {
957 assert(I != end() && "BB is not in DominanceFrontier!");
958 assert(I->second.count(Node) && "Node is not in DominanceFrontier of BB");
959 I->second.erase(Node);
962 /// compareDomSet - Return false if two domsets match. Otherwise
964 bool compareDomSet(DomSetType &DS1, const DomSetType &DS2) const {
965 std::set<BasicBlock *> tmpSet;
966 for (DomSetType::const_iterator I = DS2.begin(),
967 E = DS2.end(); I != E; ++I)
970 for (DomSetType::const_iterator I = DS1.begin(),
971 E = DS1.end(); I != E; ) {
972 BasicBlock *Node = *I++;
974 if (tmpSet.erase(Node) == 0)
975 // Node is in DS1 but not in DS2.
980 // There are nodes that are in DS2 but not in DS1.
983 // DS1 and DS2 matches.
987 /// compare - Return true if the other dominance frontier base matches
988 /// this dominance frontier base. Otherwise return false.
989 bool compare(DominanceFrontierBase &Other) const {
990 DomSetMapType tmpFrontiers;
991 for (DomSetMapType::const_iterator I = Other.begin(),
992 E = Other.end(); I != E; ++I)
993 tmpFrontiers.insert(std::make_pair(I->first, I->second));
995 for (DomSetMapType::iterator I = tmpFrontiers.begin(),
996 E = tmpFrontiers.end(); I != E; ) {
997 BasicBlock *Node = I->first;
998 const_iterator DFI = find(Node);
1002 if (compareDomSet(I->second, DFI->second))
1006 tmpFrontiers.erase(Node);
1009 if (!tmpFrontiers.empty())
1015 /// print - Convert to human readable form
1017 virtual void print(std::ostream &OS, const Module* = 0) const;
1018 void print(std::ostream *OS, const Module* M = 0) const {
1019 if (OS) print(*OS, M);
1021 virtual void dump();
1025 //===-------------------------------------
1026 /// DominanceFrontier Class - Concrete subclass of DominanceFrontierBase that is
1027 /// used to compute a forward dominator frontiers.
1029 class DominanceFrontier : public DominanceFrontierBase {
1031 static char ID; // Pass ID, replacement for typeid
1032 DominanceFrontier() :
1033 DominanceFrontierBase(&ID, false) {}
1035 BasicBlock *getRoot() const {
1036 assert(Roots.size() == 1 && "Should always have entry node!");
1040 virtual bool runOnFunction(Function &) {
1042 DominatorTree &DT = getAnalysis<DominatorTree>();
1043 Roots = DT.getRoots();
1044 assert(Roots.size() == 1 && "Only one entry block for forward domfronts!");
1045 calculate(DT, DT[Roots[0]]);
1049 virtual void getAnalysisUsage(AnalysisUsage &AU) const {
1050 AU.setPreservesAll();
1051 AU.addRequired<DominatorTree>();
1054 /// splitBlock - BB is split and now it has one successor. Update dominance
1055 /// frontier to reflect this change.
1056 void splitBlock(BasicBlock *BB);
1058 /// BasicBlock BB's new dominator is NewBB. Update BB's dominance frontier
1059 /// to reflect this change.
1060 void changeImmediateDominator(BasicBlock *BB, BasicBlock *NewBB,
1061 DominatorTree *DT) {
1062 // NewBB is now dominating BB. Which means BB's dominance
1063 // frontier is now part of NewBB's dominance frontier. However, BB
1064 // itself is not member of NewBB's dominance frontier.
1065 DominanceFrontier::iterator NewDFI = find(NewBB);
1066 DominanceFrontier::iterator DFI = find(BB);
1067 // If BB was an entry block then its frontier is empty.
1070 DominanceFrontier::DomSetType BBSet = DFI->second;
1071 for (DominanceFrontier::DomSetType::iterator BBSetI = BBSet.begin(),
1072 BBSetE = BBSet.end(); BBSetI != BBSetE; ++BBSetI) {
1073 BasicBlock *DFMember = *BBSetI;
1074 // Insert only if NewBB dominates DFMember.
1075 if (!DT->dominates(NewBB, DFMember))
1076 NewDFI->second.insert(DFMember);
1078 NewDFI->second.erase(BB);
1081 const DomSetType &calculate(const DominatorTree &DT,
1082 const DomTreeNode *Node);
1086 } // End llvm namespace