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 DominatorTree class, which provides fast and efficient
13 //===----------------------------------------------------------------------===//
15 #ifndef LLVM_ANALYSIS_DOMINATORS_H
16 #define LLVM_ANALYSIS_DOMINATORS_H
18 #include "llvm/Pass.h"
19 #include "llvm/Function.h"
20 #include "llvm/ADT/DenseMap.h"
21 #include "llvm/ADT/DepthFirstIterator.h"
22 #include "llvm/ADT/GraphTraits.h"
23 #include "llvm/ADT/SmallPtrSet.h"
24 #include "llvm/ADT/SmallVector.h"
25 #include "llvm/Support/CFG.h"
26 #include "llvm/Support/Compiler.h"
27 #include "llvm/Support/raw_ostream.h"
32 //===----------------------------------------------------------------------===//
33 /// DominatorBase - Base class that other, more interesting dominator analyses
36 template <class NodeT>
39 std::vector<NodeT*> Roots;
40 const bool IsPostDominators;
41 inline explicit DominatorBase(bool isPostDom) :
42 Roots(), IsPostDominators(isPostDom) {}
45 /// getRoots - Return the root blocks of the current CFG. This may include
46 /// multiple blocks if we are computing post dominators. For forward
47 /// dominators, this will always be a single block (the entry node).
49 inline const std::vector<NodeT*> &getRoots() const { return Roots; }
51 /// isPostDominator - Returns true if analysis based of postdoms
53 bool isPostDominator() const { return IsPostDominators; }
57 //===----------------------------------------------------------------------===//
58 // DomTreeNode - Dominator Tree Node
59 template<class NodeT> class DominatorTreeBase;
60 struct PostDominatorTree;
61 class MachineBasicBlock;
63 template <class NodeT>
64 class DomTreeNodeBase {
66 DomTreeNodeBase<NodeT> *IDom;
67 std::vector<DomTreeNodeBase<NodeT> *> Children;
68 int DFSNumIn, DFSNumOut;
70 template<class N> friend class DominatorTreeBase;
71 friend struct PostDominatorTree;
73 typedef typename std::vector<DomTreeNodeBase<NodeT> *>::iterator iterator;
74 typedef typename std::vector<DomTreeNodeBase<NodeT> *>::const_iterator
77 iterator begin() { return Children.begin(); }
78 iterator end() { return Children.end(); }
79 const_iterator begin() const { return Children.begin(); }
80 const_iterator end() const { return Children.end(); }
82 NodeT *getBlock() const { return TheBB; }
83 DomTreeNodeBase<NodeT> *getIDom() const { return IDom; }
84 const std::vector<DomTreeNodeBase<NodeT>*> &getChildren() const {
88 DomTreeNodeBase(NodeT *BB, DomTreeNodeBase<NodeT> *iDom)
89 : TheBB(BB), IDom(iDom), DFSNumIn(-1), DFSNumOut(-1) { }
91 DomTreeNodeBase<NodeT> *addChild(DomTreeNodeBase<NodeT> *C) {
92 Children.push_back(C);
96 size_t getNumChildren() const {
97 return Children.size();
100 void clearAllChildren() {
104 bool compare(DomTreeNodeBase<NodeT> *Other) {
105 if (getNumChildren() != Other->getNumChildren())
108 SmallPtrSet<NodeT *, 4> OtherChildren;
109 for (iterator I = Other->begin(), E = Other->end(); I != E; ++I) {
110 NodeT *Nd = (*I)->getBlock();
111 OtherChildren.insert(Nd);
114 for (iterator I = begin(), E = end(); I != E; ++I) {
115 NodeT *N = (*I)->getBlock();
116 if (OtherChildren.count(N) == 0)
122 void setIDom(DomTreeNodeBase<NodeT> *NewIDom) {
123 assert(IDom && "No immediate dominator?");
124 if (IDom != NewIDom) {
125 typename std::vector<DomTreeNodeBase<NodeT>*>::iterator I =
126 std::find(IDom->Children.begin(), IDom->Children.end(), this);
127 assert(I != IDom->Children.end() &&
128 "Not in immediate dominator children set!");
129 // I am no longer your child...
130 IDom->Children.erase(I);
132 // Switch to new dominator
134 IDom->Children.push_back(this);
138 /// getDFSNumIn/getDFSNumOut - These are an internal implementation detail, do
140 unsigned getDFSNumIn() const { return DFSNumIn; }
141 unsigned getDFSNumOut() const { return DFSNumOut; }
143 // Return true if this node is dominated by other. Use this only if DFS info
145 bool DominatedBy(const DomTreeNodeBase<NodeT> *other) const {
146 return this->DFSNumIn >= other->DFSNumIn &&
147 this->DFSNumOut <= other->DFSNumOut;
151 EXTERN_TEMPLATE_INSTANTIATION(class DomTreeNodeBase<BasicBlock>);
152 EXTERN_TEMPLATE_INSTANTIATION(class DomTreeNodeBase<MachineBasicBlock>);
154 template<class NodeT>
155 static raw_ostream &operator<<(raw_ostream &o,
156 const DomTreeNodeBase<NodeT> *Node) {
157 if (Node->getBlock())
158 WriteAsOperand(o, Node->getBlock(), false);
160 o << " <<exit node>>";
162 o << " {" << Node->getDFSNumIn() << "," << Node->getDFSNumOut() << "}";
167 template<class NodeT>
168 static void PrintDomTree(const DomTreeNodeBase<NodeT> *N, raw_ostream &o,
170 o.indent(2*Lev) << "[" << Lev << "] " << N;
171 for (typename DomTreeNodeBase<NodeT>::const_iterator I = N->begin(),
172 E = N->end(); I != E; ++I)
173 PrintDomTree<NodeT>(*I, o, Lev+1);
176 typedef DomTreeNodeBase<BasicBlock> DomTreeNode;
178 //===----------------------------------------------------------------------===//
179 /// DominatorTree - Calculate the immediate dominator tree for a function.
182 template<class FuncT, class N>
183 void Calculate(DominatorTreeBase<typename GraphTraits<N>::NodeType>& DT,
186 template<class NodeT>
187 class DominatorTreeBase : public DominatorBase<NodeT> {
189 typedef DenseMap<NodeT*, DomTreeNodeBase<NodeT>*> DomTreeNodeMapType;
190 DomTreeNodeMapType DomTreeNodes;
191 DomTreeNodeBase<NodeT> *RootNode;
194 unsigned int SlowQueries;
195 // Information record used during immediate dominators computation.
200 NodeT *Label, *Child;
201 unsigned Parent, Ancestor;
203 InfoRec() : DFSNum(0), Semi(0), Size(0), Label(0), Child(0), Parent(0),
207 DenseMap<NodeT*, NodeT*> IDoms;
209 // Vertex - Map the DFS number to the BasicBlock*
210 std::vector<NodeT*> Vertex;
212 // Info - Collection of information used during the computation of idoms.
213 DenseMap<NodeT*, InfoRec> Info;
216 for (typename DomTreeNodeMapType::iterator I = this->DomTreeNodes.begin(),
217 E = DomTreeNodes.end(); I != E; ++I)
219 DomTreeNodes.clear();
226 // NewBB is split and now it has one successor. Update dominator tree to
227 // reflect this change.
228 template<class N, class GraphT>
229 void Split(DominatorTreeBase<typename GraphT::NodeType>& DT,
230 typename GraphT::NodeType* NewBB) {
231 assert(std::distance(GraphT::child_begin(NewBB),
232 GraphT::child_end(NewBB)) == 1 &&
233 "NewBB should have a single successor!");
234 typename GraphT::NodeType* NewBBSucc = *GraphT::child_begin(NewBB);
236 std::vector<typename GraphT::NodeType*> PredBlocks;
237 typedef GraphTraits<Inverse<N> > InvTraits;
238 for (typename InvTraits::ChildIteratorType PI =
239 InvTraits::child_begin(NewBB),
240 PE = InvTraits::child_end(NewBB); PI != PE; ++PI)
241 PredBlocks.push_back(*PI);
243 assert(!PredBlocks.empty() && "No predblocks?");
245 bool NewBBDominatesNewBBSucc = true;
246 for (typename InvTraits::ChildIteratorType PI =
247 InvTraits::child_begin(NewBBSucc),
248 E = InvTraits::child_end(NewBBSucc); PI != E; ++PI) {
249 typename InvTraits::NodeType *ND = *PI;
250 if (ND != NewBB && !DT.dominates(NewBBSucc, ND) &&
251 DT.isReachableFromEntry(ND)) {
252 NewBBDominatesNewBBSucc = false;
257 // Find NewBB's immediate dominator and create new dominator tree node for
259 NodeT *NewBBIDom = 0;
261 for (i = 0; i < PredBlocks.size(); ++i)
262 if (DT.isReachableFromEntry(PredBlocks[i])) {
263 NewBBIDom = PredBlocks[i];
267 // It's possible that none of the predecessors of NewBB are reachable;
268 // in that case, NewBB itself is unreachable, so nothing needs to be
273 for (i = i + 1; i < PredBlocks.size(); ++i) {
274 if (DT.isReachableFromEntry(PredBlocks[i]))
275 NewBBIDom = DT.findNearestCommonDominator(NewBBIDom, PredBlocks[i]);
278 // Create the new dominator tree node... and set the idom of NewBB.
279 DomTreeNodeBase<NodeT> *NewBBNode = DT.addNewBlock(NewBB, NewBBIDom);
281 // If NewBB strictly dominates other blocks, then it is now the immediate
282 // dominator of NewBBSucc. Update the dominator tree as appropriate.
283 if (NewBBDominatesNewBBSucc) {
284 DomTreeNodeBase<NodeT> *NewBBSuccNode = DT.getNode(NewBBSucc);
285 DT.changeImmediateDominator(NewBBSuccNode, NewBBNode);
290 explicit DominatorTreeBase(bool isPostDom)
291 : DominatorBase<NodeT>(isPostDom), DFSInfoValid(false), SlowQueries(0) {}
292 virtual ~DominatorTreeBase() { reset(); }
294 /// compare - Return false if the other dominator tree base matches this
295 /// dominator tree base. Otherwise return true.
296 bool compare(DominatorTreeBase &Other) const {
298 const DomTreeNodeMapType &OtherDomTreeNodes = Other.DomTreeNodes;
299 if (DomTreeNodes.size() != OtherDomTreeNodes.size())
302 for (typename DomTreeNodeMapType::const_iterator
303 I = this->DomTreeNodes.begin(),
304 E = this->DomTreeNodes.end(); I != E; ++I) {
305 NodeT *BB = I->first;
306 typename DomTreeNodeMapType::const_iterator OI = OtherDomTreeNodes.find(BB);
307 if (OI == OtherDomTreeNodes.end())
310 DomTreeNodeBase<NodeT>* MyNd = I->second;
311 DomTreeNodeBase<NodeT>* OtherNd = OI->second;
313 if (MyNd->compare(OtherNd))
320 virtual void releaseMemory() { reset(); }
322 /// getNode - return the (Post)DominatorTree node for the specified basic
323 /// block. This is the same as using operator[] on this class.
325 inline DomTreeNodeBase<NodeT> *getNode(NodeT *BB) const {
326 typename DomTreeNodeMapType::const_iterator I = DomTreeNodes.find(BB);
327 return I != DomTreeNodes.end() ? I->second : 0;
330 /// getRootNode - This returns the entry node for the CFG of the function. If
331 /// this tree represents the post-dominance relations for a function, however,
332 /// this root may be a node with the block == NULL. This is the case when
333 /// there are multiple exit nodes from a particular function. Consumers of
334 /// post-dominance information must be capable of dealing with this
337 DomTreeNodeBase<NodeT> *getRootNode() { return RootNode; }
338 const DomTreeNodeBase<NodeT> *getRootNode() const { return RootNode; }
340 /// properlyDominates - Returns true iff this dominates N and this != N.
341 /// Note that this is not a constant time operation!
343 bool properlyDominates(const DomTreeNodeBase<NodeT> *A,
344 const DomTreeNodeBase<NodeT> *B) const {
345 if (A == 0 || B == 0) return false;
346 return dominatedBySlowTreeWalk(A, B);
349 inline bool properlyDominates(const NodeT *A, const NodeT *B) {
353 // Cast away the const qualifiers here. This is ok since
354 // this function doesn't actually return the values returned
356 return properlyDominates(getNode(const_cast<NodeT *>(A)),
357 getNode(const_cast<NodeT *>(B)));
360 bool dominatedBySlowTreeWalk(const DomTreeNodeBase<NodeT> *A,
361 const DomTreeNodeBase<NodeT> *B) const {
362 const DomTreeNodeBase<NodeT> *IDom;
363 if (A == 0 || B == 0) return false;
364 while ((IDom = B->getIDom()) != 0 && IDom != A && IDom != B)
365 B = IDom; // Walk up the tree
370 /// isReachableFromEntry - Return true if A is dominated by the entry
371 /// block of the function containing it.
372 bool isReachableFromEntry(const NodeT* A) {
373 assert(!this->isPostDominator() &&
374 "This is not implemented for post dominators");
375 return dominates(&A->getParent()->front(), A);
378 /// dominates - Returns true iff A dominates B. Note that this is not a
379 /// constant time operation!
381 inline bool dominates(const DomTreeNodeBase<NodeT> *A,
382 const DomTreeNodeBase<NodeT> *B) {
384 return true; // A node trivially dominates itself.
386 if (A == 0 || B == 0)
389 // Compare the result of the tree walk and the dfs numbers, if expensive
390 // checks are enabled.
392 assert((!DFSInfoValid ||
393 (dominatedBySlowTreeWalk(A, B) == B->DominatedBy(A))) &&
394 "Tree walk disagrees with dfs numbers!");
398 return B->DominatedBy(A);
400 // If we end up with too many slow queries, just update the
401 // DFS numbers on the theory that we are going to keep querying.
403 if (SlowQueries > 32) {
405 return B->DominatedBy(A);
408 return dominatedBySlowTreeWalk(A, B);
411 inline bool dominates(const NodeT *A, const NodeT *B) {
415 // Cast away the const qualifiers here. This is ok since
416 // this function doesn't actually return the values returned
418 return dominates(getNode(const_cast<NodeT *>(A)),
419 getNode(const_cast<NodeT *>(B)));
422 NodeT *getRoot() const {
423 assert(this->Roots.size() == 1 && "Should always have entry node!");
424 return this->Roots[0];
427 /// findNearestCommonDominator - Find nearest common dominator basic block
428 /// for basic block A and B. If there is no such block then return NULL.
429 NodeT *findNearestCommonDominator(NodeT *A, NodeT *B) {
430 assert(A->getParent() == B->getParent() &&
431 "Two blocks are not in same function");
433 // If either A or B is a entry block then it is nearest common dominator
434 // (for forward-dominators).
435 if (!this->isPostDominator()) {
436 NodeT &Entry = A->getParent()->front();
437 if (A == &Entry || B == &Entry)
441 // If B dominates A then B is nearest common dominator.
445 // If A dominates B then A is nearest common dominator.
449 DomTreeNodeBase<NodeT> *NodeA = getNode(A);
450 DomTreeNodeBase<NodeT> *NodeB = getNode(B);
452 // Collect NodeA dominators set.
453 SmallPtrSet<DomTreeNodeBase<NodeT>*, 16> NodeADoms;
454 NodeADoms.insert(NodeA);
455 DomTreeNodeBase<NodeT> *IDomA = NodeA->getIDom();
457 NodeADoms.insert(IDomA);
458 IDomA = IDomA->getIDom();
461 // Walk NodeB immediate dominators chain and find common dominator node.
462 DomTreeNodeBase<NodeT> *IDomB = NodeB->getIDom();
464 if (NodeADoms.count(IDomB) != 0)
465 return IDomB->getBlock();
467 IDomB = IDomB->getIDom();
473 const NodeT *findNearestCommonDominator(const NodeT *A, const NodeT *B) {
474 // Cast away the const qualifiers here. This is ok since
475 // const is re-introduced on the return type.
476 return findNearestCommonDominator(const_cast<NodeT *>(A),
477 const_cast<NodeT *>(B));
480 //===--------------------------------------------------------------------===//
481 // API to update (Post)DominatorTree information based on modifications to
484 /// addNewBlock - Add a new node to the dominator tree information. This
485 /// creates a new node as a child of DomBB dominator node,linking it into
486 /// the children list of the immediate dominator.
487 DomTreeNodeBase<NodeT> *addNewBlock(NodeT *BB, NodeT *DomBB) {
488 assert(getNode(BB) == 0 && "Block already in dominator tree!");
489 DomTreeNodeBase<NodeT> *IDomNode = getNode(DomBB);
490 assert(IDomNode && "Not immediate dominator specified for block!");
491 DFSInfoValid = false;
492 return DomTreeNodes[BB] =
493 IDomNode->addChild(new DomTreeNodeBase<NodeT>(BB, IDomNode));
496 /// changeImmediateDominator - This method is used to update the dominator
497 /// tree information when a node's immediate dominator changes.
499 void changeImmediateDominator(DomTreeNodeBase<NodeT> *N,
500 DomTreeNodeBase<NodeT> *NewIDom) {
501 assert(N && NewIDom && "Cannot change null node pointers!");
502 DFSInfoValid = false;
506 void changeImmediateDominator(NodeT *BB, NodeT *NewBB) {
507 changeImmediateDominator(getNode(BB), getNode(NewBB));
510 /// eraseNode - Removes a node from the dominator tree. Block must not
511 /// dominate any other blocks. Removes node from its immediate dominator's
512 /// children list. Deletes dominator node associated with basic block BB.
513 void eraseNode(NodeT *BB) {
514 DomTreeNodeBase<NodeT> *Node = getNode(BB);
515 assert(Node && "Removing node that isn't in dominator tree.");
516 assert(Node->getChildren().empty() && "Node is not a leaf node.");
518 // Remove node from immediate dominator's children list.
519 DomTreeNodeBase<NodeT> *IDom = Node->getIDom();
521 typename std::vector<DomTreeNodeBase<NodeT>*>::iterator I =
522 std::find(IDom->Children.begin(), IDom->Children.end(), Node);
523 assert(I != IDom->Children.end() &&
524 "Not in immediate dominator children set!");
525 // I am no longer your child...
526 IDom->Children.erase(I);
529 DomTreeNodes.erase(BB);
533 /// removeNode - Removes a node from the dominator tree. Block must not
534 /// dominate any other blocks. Invalidates any node pointing to removed
536 void removeNode(NodeT *BB) {
537 assert(getNode(BB) && "Removing node that isn't in dominator tree.");
538 DomTreeNodes.erase(BB);
541 /// splitBlock - BB is split and now it has one successor. Update dominator
542 /// tree to reflect this change.
543 void splitBlock(NodeT* NewBB) {
544 if (this->IsPostDominators)
545 this->Split<Inverse<NodeT*>, GraphTraits<Inverse<NodeT*> > >(*this, NewBB);
547 this->Split<NodeT*, GraphTraits<NodeT*> >(*this, NewBB);
550 /// print - Convert to human readable form
552 void print(raw_ostream &o) const {
553 o << "=============================--------------------------------\n";
554 if (this->isPostDominator())
555 o << "Inorder PostDominator Tree: ";
557 o << "Inorder Dominator Tree: ";
558 if (!this->DFSInfoValid)
559 o << "DFSNumbers invalid: " << SlowQueries << " slow queries.";
562 // The postdom tree can have a null root if there are no returns.
564 PrintDomTree<NodeT>(getRootNode(), o, 1);
568 template<class GraphT>
569 friend void Compress(DominatorTreeBase<typename GraphT::NodeType>& DT,
570 typename GraphT::NodeType* VIn);
572 template<class GraphT>
573 friend typename GraphT::NodeType* Eval(
574 DominatorTreeBase<typename GraphT::NodeType>& DT,
575 typename GraphT::NodeType* V);
577 template<class GraphT>
578 friend void Link(DominatorTreeBase<typename GraphT::NodeType>& DT,
579 unsigned DFSNumV, typename GraphT::NodeType* W,
580 typename DominatorTreeBase<typename GraphT::NodeType>::InfoRec &WInfo);
582 template<class GraphT>
583 friend unsigned DFSPass(DominatorTreeBase<typename GraphT::NodeType>& DT,
584 typename GraphT::NodeType* V,
587 template<class FuncT, class N>
588 friend void Calculate(DominatorTreeBase<typename GraphTraits<N>::NodeType>& DT,
591 /// updateDFSNumbers - Assign In and Out numbers to the nodes while walking
592 /// dominator tree in dfs order.
593 void updateDFSNumbers() {
596 SmallVector<std::pair<DomTreeNodeBase<NodeT>*,
597 typename DomTreeNodeBase<NodeT>::iterator>, 32> WorkStack;
599 DomTreeNodeBase<NodeT> *ThisRoot = getRootNode();
604 // Even in the case of multiple exits that form the post dominator root
605 // nodes, do not iterate over all exits, but start from the virtual root
606 // node. Otherwise bbs, that are not post dominated by any exit but by the
607 // virtual root node, will never be assigned a DFS number.
608 WorkStack.push_back(std::make_pair(ThisRoot, ThisRoot->begin()));
609 ThisRoot->DFSNumIn = DFSNum++;
611 while (!WorkStack.empty()) {
612 DomTreeNodeBase<NodeT> *Node = WorkStack.back().first;
613 typename DomTreeNodeBase<NodeT>::iterator ChildIt =
614 WorkStack.back().second;
616 // If we visited all of the children of this node, "recurse" back up the
617 // stack setting the DFOutNum.
618 if (ChildIt == Node->end()) {
619 Node->DFSNumOut = DFSNum++;
620 WorkStack.pop_back();
622 // Otherwise, recursively visit this child.
623 DomTreeNodeBase<NodeT> *Child = *ChildIt;
624 ++WorkStack.back().second;
626 WorkStack.push_back(std::make_pair(Child, Child->begin()));
627 Child->DFSNumIn = DFSNum++;
635 DomTreeNodeBase<NodeT> *getNodeForBlock(NodeT *BB) {
636 typename DomTreeNodeMapType::iterator I = this->DomTreeNodes.find(BB);
637 if (I != this->DomTreeNodes.end() && I->second)
640 // Haven't calculated this node yet? Get or calculate the node for the
641 // immediate dominator.
642 NodeT *IDom = getIDom(BB);
644 assert(IDom || this->DomTreeNodes[NULL]);
645 DomTreeNodeBase<NodeT> *IDomNode = getNodeForBlock(IDom);
647 // Add a new tree node for this BasicBlock, and link it as a child of
649 DomTreeNodeBase<NodeT> *C = new DomTreeNodeBase<NodeT>(BB, IDomNode);
650 return this->DomTreeNodes[BB] = IDomNode->addChild(C);
653 inline NodeT *getIDom(NodeT *BB) const {
654 typename DenseMap<NodeT*, NodeT*>::const_iterator I = IDoms.find(BB);
655 return I != IDoms.end() ? I->second : 0;
658 inline void addRoot(NodeT* BB) {
659 this->Roots.push_back(BB);
663 /// recalculate - compute a dominator tree for the given function
665 void recalculate(FT& F) {
667 this->Vertex.push_back(0);
669 if (!this->IsPostDominators) {
671 this->Roots.push_back(&F.front());
672 this->IDoms[&F.front()] = 0;
673 this->DomTreeNodes[&F.front()] = 0;
675 Calculate<FT, NodeT*>(*this, F);
677 // Initialize the roots list
678 for (typename FT::iterator I = F.begin(), E = F.end(); I != E; ++I) {
679 if (std::distance(GraphTraits<FT*>::child_begin(I),
680 GraphTraits<FT*>::child_end(I)) == 0)
683 // Prepopulate maps so that we don't get iterator invalidation issues later.
685 this->DomTreeNodes[I] = 0;
688 Calculate<FT, Inverse<NodeT*> >(*this, F);
693 EXTERN_TEMPLATE_INSTANTIATION(class DominatorTreeBase<BasicBlock>);
695 //===-------------------------------------
696 /// DominatorTree Class - Concrete subclass of DominatorTreeBase that is used to
697 /// compute a normal dominator tree.
699 class DominatorTree : public FunctionPass {
701 static char ID; // Pass ID, replacement for typeid
702 DominatorTreeBase<BasicBlock>* DT;
704 DominatorTree() : FunctionPass(ID) {
705 initializeDominatorTreePass(*PassRegistry::getPassRegistry());
706 DT = new DominatorTreeBase<BasicBlock>(false);
713 DominatorTreeBase<BasicBlock>& getBase() { return *DT; }
715 /// getRoots - Return the root blocks of the current CFG. This may include
716 /// multiple blocks if we are computing post dominators. For forward
717 /// dominators, this will always be a single block (the entry node).
719 inline const std::vector<BasicBlock*> &getRoots() const {
720 return DT->getRoots();
723 inline BasicBlock *getRoot() const {
724 return DT->getRoot();
727 inline DomTreeNode *getRootNode() const {
728 return DT->getRootNode();
731 /// compare - Return false if the other dominator tree matches this
732 /// dominator tree. Otherwise return true.
733 inline bool compare(DominatorTree &Other) const {
734 DomTreeNode *R = getRootNode();
735 DomTreeNode *OtherR = Other.getRootNode();
737 if (!R || !OtherR || R->getBlock() != OtherR->getBlock())
740 if (DT->compare(Other.getBase()))
746 virtual bool runOnFunction(Function &F);
748 virtual void verifyAnalysis() const;
750 virtual void getAnalysisUsage(AnalysisUsage &AU) const {
751 AU.setPreservesAll();
754 inline bool dominates(const DomTreeNode* A, const DomTreeNode* B) const {
755 return DT->dominates(A, B);
758 inline bool dominates(const BasicBlock* A, const BasicBlock* B) const {
759 return DT->dominates(A, B);
762 // dominates - Return true if A dominates B. This performs the
763 // special checks necessary if A and B are in the same basic block.
764 bool dominates(const Instruction *A, const Instruction *B) const;
766 bool properlyDominates(const DomTreeNode *A, const DomTreeNode *B) const {
767 return DT->properlyDominates(A, B);
770 bool properlyDominates(const BasicBlock *A, const BasicBlock *B) const {
771 return DT->properlyDominates(A, B);
774 /// findNearestCommonDominator - Find nearest common dominator basic block
775 /// for basic block A and B. If there is no such block then return NULL.
776 inline BasicBlock *findNearestCommonDominator(BasicBlock *A, BasicBlock *B) {
777 return DT->findNearestCommonDominator(A, B);
780 inline const BasicBlock *findNearestCommonDominator(const BasicBlock *A,
781 const BasicBlock *B) {
782 return DT->findNearestCommonDominator(A, B);
785 inline DomTreeNode *operator[](BasicBlock *BB) const {
786 return DT->getNode(BB);
789 /// getNode - return the (Post)DominatorTree node for the specified basic
790 /// block. This is the same as using operator[] on this class.
792 inline DomTreeNode *getNode(BasicBlock *BB) const {
793 return DT->getNode(BB);
796 /// addNewBlock - Add a new node to the dominator tree information. This
797 /// creates a new node as a child of DomBB dominator node,linking it into
798 /// the children list of the immediate dominator.
799 inline DomTreeNode *addNewBlock(BasicBlock *BB, BasicBlock *DomBB) {
800 return DT->addNewBlock(BB, DomBB);
803 /// changeImmediateDominator - This method is used to update the dominator
804 /// tree information when a node's immediate dominator changes.
806 inline void changeImmediateDominator(BasicBlock *N, BasicBlock* NewIDom) {
807 DT->changeImmediateDominator(N, NewIDom);
810 inline void changeImmediateDominator(DomTreeNode *N, DomTreeNode* NewIDom) {
811 DT->changeImmediateDominator(N, NewIDom);
814 /// eraseNode - Removes a node from the dominator tree. Block must not
815 /// dominate any other blocks. Removes node from its immediate dominator's
816 /// children list. Deletes dominator node associated with basic block BB.
817 inline void eraseNode(BasicBlock *BB) {
821 /// splitBlock - BB is split and now it has one successor. Update dominator
822 /// tree to reflect this change.
823 inline void splitBlock(BasicBlock* NewBB) {
824 DT->splitBlock(NewBB);
827 bool isReachableFromEntry(const BasicBlock* A) {
828 return DT->isReachableFromEntry(A);
832 virtual void releaseMemory() {
836 virtual void print(raw_ostream &OS, const Module* M= 0) const;
839 //===-------------------------------------
840 /// DominatorTree GraphTraits specialization so the DominatorTree can be
841 /// iterable by generic graph iterators.
843 template <> struct GraphTraits<DomTreeNode*> {
844 typedef DomTreeNode NodeType;
845 typedef NodeType::iterator ChildIteratorType;
847 static NodeType *getEntryNode(NodeType *N) {
850 static inline ChildIteratorType child_begin(NodeType *N) {
853 static inline ChildIteratorType child_end(NodeType *N) {
857 typedef df_iterator<DomTreeNode*> nodes_iterator;
859 static nodes_iterator nodes_begin(DomTreeNode *N) {
860 return df_begin(getEntryNode(N));
863 static nodes_iterator nodes_end(DomTreeNode *N) {
864 return df_end(getEntryNode(N));
868 template <> struct GraphTraits<DominatorTree*>
869 : public GraphTraits<DomTreeNode*> {
870 static NodeType *getEntryNode(DominatorTree *DT) {
871 return DT->getRootNode();
874 static nodes_iterator nodes_begin(DominatorTree *N) {
875 return df_begin(getEntryNode(N));
878 static nodes_iterator nodes_end(DominatorTree *N) {
879 return df_end(getEntryNode(N));
884 } // End llvm namespace