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 bool NewBBDominatesNewBBSucc = true;
255 for (typename GraphTraits<Inverse<N> >::ChildIteratorType PI =
256 GraphTraits<Inverse<N> >::child_begin(NewBBSucc),
257 E = GraphTraits<Inverse<N> >::child_end(NewBBSucc); PI != E; ++PI)
258 if (*PI != NewBB && !DT.dominates(NewBBSucc, *PI) &&
259 DT.isReachableFromEntry(*PI)) {
260 NewBBDominatesNewBBSucc = false;
264 // Find NewBB's immediate dominator and create new dominator tree node for
266 NodeT *NewBBIDom = 0;
268 for (i = 0; i < PredBlocks.size(); ++i)
269 if (DT.isReachableFromEntry(PredBlocks[i])) {
270 NewBBIDom = PredBlocks[i];
273 assert(i != PredBlocks.size() && "No reachable preds?");
274 for (i = i + 1; i < PredBlocks.size(); ++i) {
275 if (DT.isReachableFromEntry(PredBlocks[i]))
276 NewBBIDom = DT.findNearestCommonDominator(NewBBIDom, PredBlocks[i]);
278 assert(NewBBIDom && "No immediate dominator found??");
280 // Create the new dominator tree node... and set the idom of NewBB.
281 DomTreeNodeBase<NodeT> *NewBBNode = DT.addNewBlock(NewBB, NewBBIDom);
283 // If NewBB strictly dominates other blocks, then it is now the immediate
284 // dominator of NewBBSucc. Update the dominator tree as appropriate.
285 if (NewBBDominatesNewBBSucc) {
286 DomTreeNodeBase<NodeT> *NewBBSuccNode = DT.getNode(NewBBSucc);
287 DT.changeImmediateDominator(NewBBSuccNode, NewBBNode);
292 explicit DominatorTreeBase(bool isPostDom)
293 : DominatorBase<NodeT>(isPostDom), DFSInfoValid(false), SlowQueries(0) {}
294 virtual ~DominatorTreeBase() { reset(); }
296 // FIXME: Should remove this
297 virtual bool runOnFunction(Function &F) { return false; }
299 /// compare - Return false if the other dominator tree base matches this
300 /// dominator tree base. Otherwise return true.
301 bool compare(DominatorTreeBase &Other) const {
303 const DomTreeNodeMapType &OtherDomTreeNodes = Other.DomTreeNodes;
304 if (DomTreeNodes.size() != OtherDomTreeNodes.size())
307 SmallPtrSet<const NodeT *,4> MyBBs;
308 for (typename DomTreeNodeMapType::const_iterator
309 I = this->DomTreeNodes.begin(),
310 E = this->DomTreeNodes.end(); I != E; ++I) {
311 NodeT *BB = I->first;
312 typename DomTreeNodeMapType::const_iterator OI = OtherDomTreeNodes.find(BB);
313 if (OI == OtherDomTreeNodes.end())
316 DomTreeNodeBase<NodeT>* MyNd = I->second;
317 DomTreeNodeBase<NodeT>* OtherNd = OI->second;
319 if (MyNd->compare(OtherNd))
326 virtual void releaseMemory() { reset(); }
328 /// getNode - return the (Post)DominatorTree node for the specified basic
329 /// block. This is the same as using operator[] on this class.
331 inline DomTreeNodeBase<NodeT> *getNode(NodeT *BB) const {
332 typename DomTreeNodeMapType::const_iterator I = DomTreeNodes.find(BB);
333 return I != DomTreeNodes.end() ? I->second : 0;
336 /// getRootNode - This returns the entry node for the CFG of the function. If
337 /// this tree represents the post-dominance relations for a function, however,
338 /// this root may be a node with the block == NULL. This is the case when
339 /// there are multiple exit nodes from a particular function. Consumers of
340 /// post-dominance information must be capable of dealing with this
343 DomTreeNodeBase<NodeT> *getRootNode() { return RootNode; }
344 const DomTreeNodeBase<NodeT> *getRootNode() const { return RootNode; }
346 /// properlyDominates - Returns true iff this dominates N and this != N.
347 /// Note that this is not a constant time operation!
349 bool properlyDominates(const DomTreeNodeBase<NodeT> *A,
350 DomTreeNodeBase<NodeT> *B) const {
351 if (A == 0 || B == 0) return false;
352 return dominatedBySlowTreeWalk(A, B);
355 inline bool properlyDominates(NodeT *A, NodeT *B) {
356 return properlyDominates(getNode(A), getNode(B));
359 bool dominatedBySlowTreeWalk(const DomTreeNodeBase<NodeT> *A,
360 const DomTreeNodeBase<NodeT> *B) const {
361 const DomTreeNodeBase<NodeT> *IDom;
362 if (A == 0 || B == 0) return false;
363 while ((IDom = B->getIDom()) != 0 && IDom != A && IDom != B)
364 B = IDom; // Walk up the tree
369 /// isReachableFromEntry - Return true if A is dominated by the entry
370 /// block of the function containing it.
371 bool isReachableFromEntry(NodeT* A) {
372 assert (!this->isPostDominator()
373 && "This is not implemented for post dominators");
374 return dominates(&A->getParent()->front(), A);
377 /// dominates - Returns true iff A dominates B. Note that this is not a
378 /// constant time operation!
380 inline bool dominates(const DomTreeNodeBase<NodeT> *A,
381 DomTreeNodeBase<NodeT> *B) {
383 return true; // A node trivially dominates itself.
385 if (A == 0 || B == 0)
389 return B->DominatedBy(A);
391 // If we end up with too many slow queries, just update the
392 // DFS numbers on the theory that we are going to keep querying.
394 if (SlowQueries > 32) {
396 return B->DominatedBy(A);
399 return dominatedBySlowTreeWalk(A, B);
402 inline bool dominates(NodeT *A, NodeT *B) {
406 return dominates(getNode(A), getNode(B));
409 NodeT *getRoot() const {
410 assert(this->Roots.size() == 1 && "Should always have entry node!");
411 return this->Roots[0];
414 /// findNearestCommonDominator - Find nearest common dominator basic block
415 /// for basic block A and B. If there is no such block then return NULL.
416 NodeT *findNearestCommonDominator(NodeT *A, NodeT *B) {
418 assert (!this->isPostDominator()
419 && "This is not implemented for post dominators");
420 assert (A->getParent() == B->getParent()
421 && "Two blocks are not in same function");
423 // If either A or B is a entry block then it is nearest common dominator.
424 NodeT &Entry = A->getParent()->front();
425 if (A == &Entry || B == &Entry)
428 // If B dominates A then B is nearest common dominator.
432 // If A dominates B then A is nearest common dominator.
436 DomTreeNodeBase<NodeT> *NodeA = getNode(A);
437 DomTreeNodeBase<NodeT> *NodeB = getNode(B);
439 // Collect NodeA dominators set.
440 SmallPtrSet<DomTreeNodeBase<NodeT>*, 16> NodeADoms;
441 NodeADoms.insert(NodeA);
442 DomTreeNodeBase<NodeT> *IDomA = NodeA->getIDom();
444 NodeADoms.insert(IDomA);
445 IDomA = IDomA->getIDom();
448 // Walk NodeB immediate dominators chain and find common dominator node.
449 DomTreeNodeBase<NodeT> *IDomB = NodeB->getIDom();
451 if (NodeADoms.count(IDomB) != 0)
452 return IDomB->getBlock();
454 IDomB = IDomB->getIDom();
460 //===--------------------------------------------------------------------===//
461 // API to update (Post)DominatorTree information based on modifications to
464 /// addNewBlock - Add a new node to the dominator tree information. This
465 /// creates a new node as a child of DomBB dominator node,linking it into
466 /// the children list of the immediate dominator.
467 DomTreeNodeBase<NodeT> *addNewBlock(NodeT *BB, NodeT *DomBB) {
468 assert(getNode(BB) == 0 && "Block already in dominator tree!");
469 DomTreeNodeBase<NodeT> *IDomNode = getNode(DomBB);
470 assert(IDomNode && "Not immediate dominator specified for block!");
471 DFSInfoValid = false;
472 return DomTreeNodes[BB] =
473 IDomNode->addChild(new DomTreeNodeBase<NodeT>(BB, IDomNode));
476 /// changeImmediateDominator - This method is used to update the dominator
477 /// tree information when a node's immediate dominator changes.
479 void changeImmediateDominator(DomTreeNodeBase<NodeT> *N,
480 DomTreeNodeBase<NodeT> *NewIDom) {
481 assert(N && NewIDom && "Cannot change null node pointers!");
482 DFSInfoValid = false;
486 void changeImmediateDominator(NodeT *BB, NodeT *NewBB) {
487 changeImmediateDominator(getNode(BB), getNode(NewBB));
490 /// eraseNode - Removes a node from the dominator tree. Block must not
491 /// domiante any other blocks. Removes node from its immediate dominator's
492 /// children list. Deletes dominator node associated with basic block BB.
493 void eraseNode(NodeT *BB) {
494 DomTreeNodeBase<NodeT> *Node = getNode(BB);
495 assert (Node && "Removing node that isn't in dominator tree.");
496 assert (Node->getChildren().empty() && "Node is not a leaf node.");
498 // Remove node from immediate dominator's children list.
499 DomTreeNodeBase<NodeT> *IDom = Node->getIDom();
501 typename std::vector<DomTreeNodeBase<NodeT>*>::iterator I =
502 std::find(IDom->Children.begin(), IDom->Children.end(), Node);
503 assert(I != IDom->Children.end() &&
504 "Not in immediate dominator children set!");
505 // I am no longer your child...
506 IDom->Children.erase(I);
509 DomTreeNodes.erase(BB);
513 /// removeNode - Removes a node from the dominator tree. Block must not
514 /// dominate any other blocks. Invalidates any node pointing to removed
516 void removeNode(NodeT *BB) {
517 assert(getNode(BB) && "Removing node that isn't in dominator tree.");
518 DomTreeNodes.erase(BB);
521 /// splitBlock - BB is split and now it has one successor. Update dominator
522 /// tree to reflect this change.
523 void splitBlock(NodeT* NewBB) {
524 if (this->IsPostDominators)
525 this->Split<Inverse<NodeT*>, GraphTraits<Inverse<NodeT*> > >(*this, NewBB);
527 this->Split<NodeT*, GraphTraits<NodeT*> >(*this, NewBB);
530 /// print - Convert to human readable form
532 virtual void print(std::ostream &o, const Module* ) const {
533 o << "=============================--------------------------------\n";
534 if (this->isPostDominator())
535 o << "Inorder PostDominator Tree: ";
537 o << "Inorder Dominator Tree: ";
538 if (this->DFSInfoValid)
539 o << "DFSNumbers invalid: " << SlowQueries << " slow queries.";
542 PrintDomTree<NodeT>(getRootNode(), o, 1);
545 void print(std::ostream *OS, const Module* M = 0) const {
546 if (OS) print(*OS, M);
549 virtual void dump() {
554 template<class GraphT>
555 friend void Compress(DominatorTreeBase<typename GraphT::NodeType>& DT,
556 typename GraphT::NodeType* VIn);
558 template<class GraphT>
559 friend typename GraphT::NodeType* Eval(
560 DominatorTreeBase<typename GraphT::NodeType>& DT,
561 typename GraphT::NodeType* V);
563 template<class GraphT>
564 friend void Link(DominatorTreeBase<typename GraphT::NodeType>& DT,
565 unsigned DFSNumV, typename GraphT::NodeType* W,
566 typename DominatorTreeBase<typename GraphT::NodeType>::InfoRec &WInfo);
568 template<class GraphT>
569 friend unsigned DFSPass(DominatorTreeBase<typename GraphT::NodeType>& DT,
570 typename GraphT::NodeType* V,
573 template<class FuncT, class N>
574 friend void Calculate(DominatorTreeBase<typename GraphTraits<N>::NodeType>& DT,
577 /// updateDFSNumbers - Assign In and Out numbers to the nodes while walking
578 /// dominator tree in dfs order.
579 void updateDFSNumbers() {
582 SmallVector<std::pair<DomTreeNodeBase<NodeT>*,
583 typename DomTreeNodeBase<NodeT>::iterator>, 32> WorkStack;
585 for (unsigned i = 0, e = (unsigned)this->Roots.size(); i != e; ++i) {
586 DomTreeNodeBase<NodeT> *ThisRoot = getNode(this->Roots[i]);
587 WorkStack.push_back(std::make_pair(ThisRoot, ThisRoot->begin()));
588 ThisRoot->DFSNumIn = DFSNum++;
590 while (!WorkStack.empty()) {
591 DomTreeNodeBase<NodeT> *Node = WorkStack.back().first;
592 typename DomTreeNodeBase<NodeT>::iterator ChildIt =
593 WorkStack.back().second;
595 // If we visited all of the children of this node, "recurse" back up the
596 // stack setting the DFOutNum.
597 if (ChildIt == Node->end()) {
598 Node->DFSNumOut = DFSNum++;
599 WorkStack.pop_back();
601 // Otherwise, recursively visit this child.
602 DomTreeNodeBase<NodeT> *Child = *ChildIt;
603 ++WorkStack.back().second;
605 WorkStack.push_back(std::make_pair(Child, Child->begin()));
606 Child->DFSNumIn = DFSNum++;
615 DomTreeNodeBase<NodeT> *getNodeForBlock(NodeT *BB) {
616 if (DomTreeNodeBase<NodeT> *BBNode = this->DomTreeNodes[BB])
619 // Haven't calculated this node yet? Get or calculate the node for the
620 // immediate dominator.
621 NodeT *IDom = getIDom(BB);
623 assert(IDom || this->DomTreeNodes[NULL]);
624 DomTreeNodeBase<NodeT> *IDomNode = getNodeForBlock(IDom);
626 // Add a new tree node for this BasicBlock, and link it as a child of
628 DomTreeNodeBase<NodeT> *C = new DomTreeNodeBase<NodeT>(BB, IDomNode);
629 return this->DomTreeNodes[BB] = IDomNode->addChild(C);
632 inline NodeT *getIDom(NodeT *BB) const {
633 typename DenseMap<NodeT*, NodeT*>::const_iterator I = IDoms.find(BB);
634 return I != IDoms.end() ? I->second : 0;
637 inline void addRoot(NodeT* BB) {
638 this->Roots.push_back(BB);
642 /// recalculate - compute a dominator tree for the given function
644 void recalculate(FT& F) {
645 if (!this->IsPostDominators) {
649 this->Roots.push_back(&F.front());
650 this->IDoms[&F.front()] = 0;
651 this->DomTreeNodes[&F.front()] = 0;
652 this->Vertex.push_back(0);
654 Calculate<FT, NodeT*>(*this, F);
658 reset(); // Reset from the last time we were run...
660 // Initialize the roots list
661 for (typename FT::iterator I = F.begin(), E = F.end(); I != E; ++I) {
662 if (std::distance(GraphTraits<FT*>::child_begin(I),
663 GraphTraits<FT*>::child_end(I)) == 0)
666 // Prepopulate maps so that we don't get iterator invalidation issues later.
668 this->DomTreeNodes[I] = 0;
671 this->Vertex.push_back(0);
673 Calculate<FT, Inverse<NodeT*> >(*this, F);
678 EXTERN_TEMPLATE_INSTANTIATION(class DominatorTreeBase<BasicBlock>);
680 //===-------------------------------------
681 /// DominatorTree Class - Concrete subclass of DominatorTreeBase that is used to
682 /// compute a normal dominator tree.
684 class DominatorTree : public FunctionPass {
686 static char ID; // Pass ID, replacement for typeid
687 DominatorTreeBase<BasicBlock>* DT;
689 DominatorTree() : FunctionPass(&ID) {
690 DT = new DominatorTreeBase<BasicBlock>(false);
698 DominatorTreeBase<BasicBlock>& getBase() { return *DT; }
700 /// getRoots - Return the root blocks of the current CFG. This may include
701 /// multiple blocks if we are computing post dominators. For forward
702 /// dominators, this will always be a single block (the entry node).
704 inline const std::vector<BasicBlock*> &getRoots() const {
705 return DT->getRoots();
708 inline BasicBlock *getRoot() const {
709 return DT->getRoot();
712 inline DomTreeNode *getRootNode() const {
713 return DT->getRootNode();
716 /// compare - Return false if the other dominator tree matches this
717 /// dominator tree. Otherwise return true.
718 inline bool compare(DominatorTree &Other) const {
719 DomTreeNode *R = getRootNode();
720 DomTreeNode *OtherR = Other.getRootNode();
722 if (!R || !OtherR || R->getBlock() != OtherR->getBlock())
725 if (DT->compare(Other.getBase()))
731 virtual bool runOnFunction(Function &F);
733 virtual void getAnalysisUsage(AnalysisUsage &AU) const {
734 AU.setPreservesAll();
737 inline bool dominates(DomTreeNode* A, DomTreeNode* B) const {
738 return DT->dominates(A, B);
741 inline bool dominates(BasicBlock* A, BasicBlock* B) const {
742 return DT->dominates(A, B);
745 // dominates - Return true if A dominates B. This performs the
746 // special checks necessary if A and B are in the same basic block.
747 bool dominates(Instruction *A, Instruction *B) const {
748 BasicBlock *BBA = A->getParent(), *BBB = B->getParent();
749 if (BBA != BBB) return DT->dominates(BBA, BBB);
751 // It is not possible to determine dominance between two PHI nodes
752 // based on their ordering.
753 if (isa<PHINode>(A) && isa<PHINode>(B))
756 // Loop through the basic block until we find A or B.
757 BasicBlock::iterator I = BBA->begin();
758 for (; &*I != A && &*I != B; ++I) /*empty*/;
760 //if(!DT.IsPostDominators) {
761 // A dominates B if it is found first in the basic block.
764 // // A post-dominates B if B is found first in the basic block.
769 inline bool properlyDominates(const DomTreeNode* A, DomTreeNode* B) const {
770 return DT->properlyDominates(A, B);
773 inline bool properlyDominates(BasicBlock* A, BasicBlock* B) const {
774 return DT->properlyDominates(A, B);
777 /// findNearestCommonDominator - Find nearest common dominator basic block
778 /// for basic block A and B. If there is no such block then return NULL.
779 inline BasicBlock *findNearestCommonDominator(BasicBlock *A, BasicBlock *B) {
780 return DT->findNearestCommonDominator(A, B);
783 inline DomTreeNode *operator[](BasicBlock *BB) const {
784 return DT->getNode(BB);
787 /// getNode - return the (Post)DominatorTree node for the specified basic
788 /// block. This is the same as using operator[] on this class.
790 inline DomTreeNode *getNode(BasicBlock *BB) const {
791 return DT->getNode(BB);
794 /// addNewBlock - Add a new node to the dominator tree information. This
795 /// creates a new node as a child of DomBB dominator node,linking it into
796 /// the children list of the immediate dominator.
797 inline DomTreeNode *addNewBlock(BasicBlock *BB, BasicBlock *DomBB) {
798 return DT->addNewBlock(BB, DomBB);
801 /// changeImmediateDominator - This method is used to update the dominator
802 /// tree information when a node's immediate dominator changes.
804 inline void changeImmediateDominator(BasicBlock *N, BasicBlock* NewIDom) {
805 DT->changeImmediateDominator(N, NewIDom);
808 inline void changeImmediateDominator(DomTreeNode *N, DomTreeNode* NewIDom) {
809 DT->changeImmediateDominator(N, NewIDom);
812 /// eraseNode - Removes a node from the dominator tree. Block must not
813 /// domiante any other blocks. Removes node from its immediate dominator's
814 /// children list. Deletes dominator node associated with basic block BB.
815 inline void eraseNode(BasicBlock *BB) {
819 /// splitBlock - BB is split and now it has one successor. Update dominator
820 /// tree to reflect this change.
821 inline void splitBlock(BasicBlock* NewBB) {
822 DT->splitBlock(NewBB);
825 bool isReachableFromEntry(BasicBlock* A) {
826 return DT->isReachableFromEntry(A);
830 virtual void releaseMemory() {
834 virtual void print(std::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) {
858 template <> struct GraphTraits<DominatorTree*>
859 : public GraphTraits<DomTreeNode *> {
860 static NodeType *getEntryNode(DominatorTree *DT) {
861 return DT->getRootNode();
866 //===----------------------------------------------------------------------===//
867 /// DominanceFrontierBase - Common base class for computing forward and inverse
868 /// dominance frontiers for a function.
870 class DominanceFrontierBase : public FunctionPass {
872 typedef std::set<BasicBlock*> DomSetType; // Dom set for a bb
873 typedef std::map<BasicBlock*, DomSetType> DomSetMapType; // Dom set map
875 DomSetMapType Frontiers;
876 std::vector<BasicBlock*> Roots;
877 const bool IsPostDominators;
880 DominanceFrontierBase(void *ID, bool isPostDom)
881 : FunctionPass(ID), IsPostDominators(isPostDom) {}
883 /// getRoots - Return the root blocks of the current CFG. This may include
884 /// multiple blocks if we are computing post dominators. For forward
885 /// dominators, this will always be a single block (the entry node).
887 inline const std::vector<BasicBlock*> &getRoots() const { return Roots; }
889 /// isPostDominator - Returns true if analysis based of postdoms
891 bool isPostDominator() const { return IsPostDominators; }
893 virtual void releaseMemory() { Frontiers.clear(); }
895 // Accessor interface:
896 typedef DomSetMapType::iterator iterator;
897 typedef DomSetMapType::const_iterator const_iterator;
898 iterator begin() { return Frontiers.begin(); }
899 const_iterator begin() const { return Frontiers.begin(); }
900 iterator end() { return Frontiers.end(); }
901 const_iterator end() const { return Frontiers.end(); }
902 iterator find(BasicBlock *B) { return Frontiers.find(B); }
903 const_iterator find(BasicBlock *B) const { return Frontiers.find(B); }
905 void addBasicBlock(BasicBlock *BB, const DomSetType &frontier) {
906 assert(find(BB) == end() && "Block already in DominanceFrontier!");
907 Frontiers.insert(std::make_pair(BB, frontier));
910 /// removeBlock - Remove basic block BB's frontier.
911 void removeBlock(BasicBlock *BB) {
912 assert(find(BB) != end() && "Block is not in DominanceFrontier!");
913 for (iterator I = begin(), E = end(); I != E; ++I)
918 void addToFrontier(iterator I, BasicBlock *Node) {
919 assert(I != end() && "BB is not in DominanceFrontier!");
920 I->second.insert(Node);
923 void removeFromFrontier(iterator I, BasicBlock *Node) {
924 assert(I != end() && "BB is not in DominanceFrontier!");
925 assert(I->second.count(Node) && "Node is not in DominanceFrontier of BB");
926 I->second.erase(Node);
929 /// compareDomSet - Return false if two domsets match. Otherwise
931 bool compareDomSet(DomSetType &DS1, const DomSetType &DS2) const {
932 std::set<BasicBlock *> tmpSet;
933 for (DomSetType::const_iterator I = DS2.begin(),
934 E = DS2.end(); I != E; ++I)
937 for (DomSetType::const_iterator I = DS1.begin(),
938 E = DS1.end(); I != E; ) {
939 BasicBlock *Node = *I++;
941 if (tmpSet.erase(Node) == 0)
942 // Node is in DS1 but not in DS2.
947 // There are nodes that are in DS2 but not in DS1.
950 // DS1 and DS2 matches.
954 /// compare - Return true if the other dominance frontier base matches
955 /// this dominance frontier base. Otherwise return false.
956 bool compare(DominanceFrontierBase &Other) const {
957 DomSetMapType tmpFrontiers;
958 for (DomSetMapType::const_iterator I = Other.begin(),
959 E = Other.end(); I != E; ++I)
960 tmpFrontiers.insert(std::make_pair(I->first, I->second));
962 for (DomSetMapType::iterator I = tmpFrontiers.begin(),
963 E = tmpFrontiers.end(); I != E; ) {
964 BasicBlock *Node = I->first;
965 const_iterator DFI = find(Node);
969 if (compareDomSet(I->second, DFI->second))
973 tmpFrontiers.erase(Node);
976 if (!tmpFrontiers.empty())
982 /// print - Convert to human readable form
984 virtual void print(std::ostream &OS, const Module* = 0) const;
985 void print(std::ostream *OS, const Module* M = 0) const {
986 if (OS) print(*OS, M);
992 //===-------------------------------------
993 /// DominanceFrontier Class - Concrete subclass of DominanceFrontierBase that is
994 /// used to compute a forward dominator frontiers.
996 class DominanceFrontier : public DominanceFrontierBase {
998 static char ID; // Pass ID, replacement for typeid
999 DominanceFrontier() :
1000 DominanceFrontierBase(&ID, false) {}
1002 BasicBlock *getRoot() const {
1003 assert(Roots.size() == 1 && "Should always have entry node!");
1007 virtual bool runOnFunction(Function &) {
1009 DominatorTree &DT = getAnalysis<DominatorTree>();
1010 Roots = DT.getRoots();
1011 assert(Roots.size() == 1 && "Only one entry block for forward domfronts!");
1012 calculate(DT, DT[Roots[0]]);
1016 virtual void getAnalysisUsage(AnalysisUsage &AU) const {
1017 AU.setPreservesAll();
1018 AU.addRequired<DominatorTree>();
1021 /// splitBlock - BB is split and now it has one successor. Update dominance
1022 /// frontier to reflect this change.
1023 void splitBlock(BasicBlock *BB);
1025 /// BasicBlock BB's new dominator is NewBB. Update BB's dominance frontier
1026 /// to reflect this change.
1027 void changeImmediateDominator(BasicBlock *BB, BasicBlock *NewBB,
1028 DominatorTree *DT) {
1029 // NewBB is now dominating BB. Which means BB's dominance
1030 // frontier is now part of NewBB's dominance frontier. However, BB
1031 // itself is not member of NewBB's dominance frontier.
1032 DominanceFrontier::iterator NewDFI = find(NewBB);
1033 DominanceFrontier::iterator DFI = find(BB);
1034 // If BB was an entry block then its frontier is empty.
1037 DominanceFrontier::DomSetType BBSet = DFI->second;
1038 for (DominanceFrontier::DomSetType::iterator BBSetI = BBSet.begin(),
1039 BBSetE = BBSet.end(); BBSetI != BBSetE; ++BBSetI) {
1040 BasicBlock *DFMember = *BBSetI;
1041 // Insert only if NewBB dominates DFMember.
1042 if (!DT->dominates(NewBB, DFMember))
1043 NewDFI->second.insert(DFMember);
1045 NewDFI->second.erase(BB);
1048 const DomSetType &calculate(const DominatorTree &DT,
1049 const DomTreeNode *Node);
1053 } // End llvm namespace