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"
35 #include "llvm/Support/raw_ostream.h"
42 //===----------------------------------------------------------------------===//
43 /// DominatorBase - Base class that other, more interesting dominator analyses
46 template <class NodeT>
49 std::vector<NodeT*> Roots;
50 const bool IsPostDominators;
51 inline explicit DominatorBase(bool isPostDom) :
52 Roots(), IsPostDominators(isPostDom) {}
55 /// getRoots - Return the root blocks of the current CFG. This may include
56 /// multiple blocks if we are computing post dominators. For forward
57 /// dominators, this will always be a single block (the entry node).
59 inline const std::vector<NodeT*> &getRoots() const { return Roots; }
61 /// isPostDominator - Returns true if analysis based of postdoms
63 bool isPostDominator() const { return IsPostDominators; }
67 //===----------------------------------------------------------------------===//
68 // DomTreeNode - Dominator Tree Node
69 template<class NodeT> class DominatorTreeBase;
70 struct PostDominatorTree;
71 class MachineBasicBlock;
73 template <class NodeT>
74 class DomTreeNodeBase {
76 DomTreeNodeBase<NodeT> *IDom;
77 std::vector<DomTreeNodeBase<NodeT> *> Children;
78 int DFSNumIn, DFSNumOut;
80 template<class N> friend class DominatorTreeBase;
81 friend struct PostDominatorTree;
83 typedef typename std::vector<DomTreeNodeBase<NodeT> *>::iterator iterator;
84 typedef typename std::vector<DomTreeNodeBase<NodeT> *>::const_iterator
87 iterator begin() { return Children.begin(); }
88 iterator end() { return Children.end(); }
89 const_iterator begin() const { return Children.begin(); }
90 const_iterator end() const { return Children.end(); }
92 NodeT *getBlock() const { return TheBB; }
93 DomTreeNodeBase<NodeT> *getIDom() const { return IDom; }
94 const std::vector<DomTreeNodeBase<NodeT>*> &getChildren() const {
98 DomTreeNodeBase(NodeT *BB, DomTreeNodeBase<NodeT> *iDom)
99 : TheBB(BB), IDom(iDom), DFSNumIn(-1), DFSNumOut(-1) { }
101 DomTreeNodeBase<NodeT> *addChild(DomTreeNodeBase<NodeT> *C) {
102 Children.push_back(C);
106 size_t getNumChildren() const {
107 return Children.size();
110 void clearAllChildren() {
114 bool compare(DomTreeNodeBase<NodeT> *Other) {
115 if (getNumChildren() != Other->getNumChildren())
118 SmallPtrSet<NodeT *, 4> OtherChildren;
119 for(iterator I = Other->begin(), E = Other->end(); I != E; ++I) {
120 NodeT *Nd = (*I)->getBlock();
121 OtherChildren.insert(Nd);
124 for(iterator I = begin(), E = end(); I != E; ++I) {
125 NodeT *N = (*I)->getBlock();
126 if (OtherChildren.count(N) == 0)
132 void setIDom(DomTreeNodeBase<NodeT> *NewIDom) {
133 assert(IDom && "No immediate dominator?");
134 if (IDom != NewIDom) {
135 typename std::vector<DomTreeNodeBase<NodeT>*>::iterator I =
136 std::find(IDom->Children.begin(), IDom->Children.end(), this);
137 assert(I != IDom->Children.end() &&
138 "Not in immediate dominator children set!");
139 // I am no longer your child...
140 IDom->Children.erase(I);
142 // Switch to new dominator
144 IDom->Children.push_back(this);
148 /// getDFSNumIn/getDFSNumOut - These are an internal implementation detail, do
150 unsigned getDFSNumIn() const { return DFSNumIn; }
151 unsigned getDFSNumOut() const { return DFSNumOut; }
153 // Return true if this node is dominated by other. Use this only if DFS info
155 bool DominatedBy(const DomTreeNodeBase<NodeT> *other) const {
156 return this->DFSNumIn >= other->DFSNumIn &&
157 this->DFSNumOut <= other->DFSNumOut;
161 EXTERN_TEMPLATE_INSTANTIATION(class DomTreeNodeBase<BasicBlock>);
162 EXTERN_TEMPLATE_INSTANTIATION(class DomTreeNodeBase<MachineBasicBlock>);
164 template<class NodeT>
165 static raw_ostream &operator<<(raw_ostream &o,
166 const DomTreeNodeBase<NodeT> *Node) {
167 if (Node->getBlock())
168 WriteAsOperand(o, Node->getBlock(), false);
170 o << " <<exit node>>";
172 o << " {" << Node->getDFSNumIn() << "," << Node->getDFSNumOut() << "}";
177 template<class NodeT>
178 static void PrintDomTree(const DomTreeNodeBase<NodeT> *N, raw_ostream &o,
180 o.indent(2*Lev) << "[" << Lev << "] " << N;
181 for (typename DomTreeNodeBase<NodeT>::const_iterator I = N->begin(),
182 E = N->end(); I != E; ++I)
183 PrintDomTree<NodeT>(*I, o, Lev+1);
186 typedef DomTreeNodeBase<BasicBlock> DomTreeNode;
188 //===----------------------------------------------------------------------===//
189 /// DominatorTree - Calculate the immediate dominator tree for a function.
192 template<class FuncT, class N>
193 void Calculate(DominatorTreeBase<typename GraphTraits<N>::NodeType>& DT,
196 template<class NodeT>
197 class DominatorTreeBase : public DominatorBase<NodeT> {
199 typedef DenseMap<NodeT*, DomTreeNodeBase<NodeT>*> DomTreeNodeMapType;
200 DomTreeNodeMapType DomTreeNodes;
201 DomTreeNodeBase<NodeT> *RootNode;
204 unsigned int SlowQueries;
205 // Information record used during immediate dominators computation.
210 NodeT *Label, *Child;
211 unsigned Parent, Ancestor;
213 std::vector<NodeT*> Bucket;
215 InfoRec() : DFSNum(0), Semi(0), Size(0), Label(0), Child(0), Parent(0),
219 DenseMap<NodeT*, NodeT*> IDoms;
221 // Vertex - Map the DFS number to the BasicBlock*
222 std::vector<NodeT*> Vertex;
224 // Info - Collection of information used during the computation of idoms.
225 DenseMap<NodeT*, InfoRec> Info;
228 for (typename DomTreeNodeMapType::iterator I = this->DomTreeNodes.begin(),
229 E = DomTreeNodes.end(); I != E; ++I)
231 DomTreeNodes.clear();
238 // NewBB is split and now it has one successor. Update dominator tree to
239 // reflect this change.
240 template<class N, class GraphT>
241 void Split(DominatorTreeBase<typename GraphT::NodeType>& DT,
242 typename GraphT::NodeType* NewBB) {
243 assert(std::distance(GraphT::child_begin(NewBB), GraphT::child_end(NewBB)) == 1
244 && "NewBB should have a single successor!");
245 typename GraphT::NodeType* NewBBSucc = *GraphT::child_begin(NewBB);
247 std::vector<typename GraphT::NodeType*> PredBlocks;
248 for (typename GraphTraits<Inverse<N> >::ChildIteratorType PI =
249 GraphTraits<Inverse<N> >::child_begin(NewBB),
250 PE = GraphTraits<Inverse<N> >::child_end(NewBB); PI != PE; ++PI)
251 PredBlocks.push_back(*PI);
253 assert(!PredBlocks.empty() && "No predblocks??");
255 bool NewBBDominatesNewBBSucc = true;
256 for (typename GraphTraits<Inverse<N> >::ChildIteratorType PI =
257 GraphTraits<Inverse<N> >::child_begin(NewBBSucc),
258 E = GraphTraits<Inverse<N> >::child_end(NewBBSucc); PI != E; ++PI)
259 if (*PI != NewBB && !DT.dominates(NewBBSucc, *PI) &&
260 DT.isReachableFromEntry(*PI)) {
261 NewBBDominatesNewBBSucc = false;
265 // Find NewBB's immediate dominator and create new dominator tree node for
267 NodeT *NewBBIDom = 0;
269 for (i = 0; i < PredBlocks.size(); ++i)
270 if (DT.isReachableFromEntry(PredBlocks[i])) {
271 NewBBIDom = PredBlocks[i];
275 // It's possible that none of the predecessors of NewBB are reachable;
276 // in that case, NewBB itself is unreachable, so nothing needs to be
281 for (i = i + 1; i < PredBlocks.size(); ++i) {
282 if (DT.isReachableFromEntry(PredBlocks[i]))
283 NewBBIDom = DT.findNearestCommonDominator(NewBBIDom, PredBlocks[i]);
286 // Create the new dominator tree node... and set the idom of NewBB.
287 DomTreeNodeBase<NodeT> *NewBBNode = DT.addNewBlock(NewBB, NewBBIDom);
289 // If NewBB strictly dominates other blocks, then it is now the immediate
290 // dominator of NewBBSucc. Update the dominator tree as appropriate.
291 if (NewBBDominatesNewBBSucc) {
292 DomTreeNodeBase<NodeT> *NewBBSuccNode = DT.getNode(NewBBSucc);
293 DT.changeImmediateDominator(NewBBSuccNode, NewBBNode);
298 explicit DominatorTreeBase(bool isPostDom)
299 : DominatorBase<NodeT>(isPostDom), DFSInfoValid(false), SlowQueries(0) {}
300 virtual ~DominatorTreeBase() { reset(); }
302 // FIXME: Should remove this
303 virtual bool runOnFunction(Function &F) { return false; }
305 /// compare - Return false if the other dominator tree base matches this
306 /// dominator tree base. Otherwise return true.
307 bool compare(DominatorTreeBase &Other) const {
309 const DomTreeNodeMapType &OtherDomTreeNodes = Other.DomTreeNodes;
310 if (DomTreeNodes.size() != OtherDomTreeNodes.size())
313 SmallPtrSet<const NodeT *,4> MyBBs;
314 for (typename DomTreeNodeMapType::const_iterator
315 I = this->DomTreeNodes.begin(),
316 E = this->DomTreeNodes.end(); I != E; ++I) {
317 NodeT *BB = I->first;
318 typename DomTreeNodeMapType::const_iterator OI = OtherDomTreeNodes.find(BB);
319 if (OI == OtherDomTreeNodes.end())
322 DomTreeNodeBase<NodeT>* MyNd = I->second;
323 DomTreeNodeBase<NodeT>* OtherNd = OI->second;
325 if (MyNd->compare(OtherNd))
332 virtual void releaseMemory() { reset(); }
334 /// getNode - return the (Post)DominatorTree node for the specified basic
335 /// block. This is the same as using operator[] on this class.
337 inline DomTreeNodeBase<NodeT> *getNode(NodeT *BB) const {
338 typename DomTreeNodeMapType::const_iterator I = DomTreeNodes.find(BB);
339 return I != DomTreeNodes.end() ? I->second : 0;
342 /// getRootNode - This returns the entry node for the CFG of the function. If
343 /// this tree represents the post-dominance relations for a function, however,
344 /// this root may be a node with the block == NULL. This is the case when
345 /// there are multiple exit nodes from a particular function. Consumers of
346 /// post-dominance information must be capable of dealing with this
349 DomTreeNodeBase<NodeT> *getRootNode() { return RootNode; }
350 const DomTreeNodeBase<NodeT> *getRootNode() const { return RootNode; }
352 /// properlyDominates - Returns true iff this dominates N and this != N.
353 /// Note that this is not a constant time operation!
355 bool properlyDominates(const DomTreeNodeBase<NodeT> *A,
356 DomTreeNodeBase<NodeT> *B) const {
357 if (A == 0 || B == 0) return false;
358 return dominatedBySlowTreeWalk(A, B);
361 inline bool properlyDominates(NodeT *A, NodeT *B) {
362 return properlyDominates(getNode(A), getNode(B));
365 bool dominatedBySlowTreeWalk(const DomTreeNodeBase<NodeT> *A,
366 const DomTreeNodeBase<NodeT> *B) const {
367 const DomTreeNodeBase<NodeT> *IDom;
368 if (A == 0 || B == 0) return false;
369 while ((IDom = B->getIDom()) != 0 && IDom != A && IDom != B)
370 B = IDom; // Walk up the tree
375 /// isReachableFromEntry - Return true if A is dominated by the entry
376 /// block of the function containing it.
377 bool isReachableFromEntry(NodeT* A) {
378 assert (!this->isPostDominator()
379 && "This is not implemented for post dominators");
380 return dominates(&A->getParent()->front(), A);
383 /// dominates - Returns true iff A dominates B. Note that this is not a
384 /// constant time operation!
386 inline bool dominates(const DomTreeNodeBase<NodeT> *A,
387 DomTreeNodeBase<NodeT> *B) {
389 return true; // A node trivially dominates itself.
391 if (A == 0 || B == 0)
395 return B->DominatedBy(A);
397 // If we end up with too many slow queries, just update the
398 // DFS numbers on the theory that we are going to keep querying.
400 if (SlowQueries > 32) {
402 return B->DominatedBy(A);
405 return dominatedBySlowTreeWalk(A, B);
408 inline bool dominates(NodeT *A, NodeT *B) {
412 return dominates(getNode(A), getNode(B));
415 NodeT *getRoot() const {
416 assert(this->Roots.size() == 1 && "Should always have entry node!");
417 return this->Roots[0];
420 /// findNearestCommonDominator - Find nearest common dominator basic block
421 /// for basic block A and B. If there is no such block then return NULL.
422 NodeT *findNearestCommonDominator(NodeT *A, NodeT *B) {
424 assert (!this->isPostDominator()
425 && "This is not implemented for post dominators");
426 assert (A->getParent() == B->getParent()
427 && "Two blocks are not in same function");
429 // If either A or B is a entry block then it is nearest common dominator.
430 NodeT &Entry = A->getParent()->front();
431 if (A == &Entry || B == &Entry)
434 // If B dominates A then B is nearest common dominator.
438 // If A dominates B then A is nearest common dominator.
442 DomTreeNodeBase<NodeT> *NodeA = getNode(A);
443 DomTreeNodeBase<NodeT> *NodeB = getNode(B);
445 // Collect NodeA dominators set.
446 SmallPtrSet<DomTreeNodeBase<NodeT>*, 16> NodeADoms;
447 NodeADoms.insert(NodeA);
448 DomTreeNodeBase<NodeT> *IDomA = NodeA->getIDom();
450 NodeADoms.insert(IDomA);
451 IDomA = IDomA->getIDom();
454 // Walk NodeB immediate dominators chain and find common dominator node.
455 DomTreeNodeBase<NodeT> *IDomB = NodeB->getIDom();
457 if (NodeADoms.count(IDomB) != 0)
458 return IDomB->getBlock();
460 IDomB = IDomB->getIDom();
466 //===--------------------------------------------------------------------===//
467 // API to update (Post)DominatorTree information based on modifications to
470 /// addNewBlock - Add a new node to the dominator tree information. This
471 /// creates a new node as a child of DomBB dominator node,linking it into
472 /// the children list of the immediate dominator.
473 DomTreeNodeBase<NodeT> *addNewBlock(NodeT *BB, NodeT *DomBB) {
474 assert(getNode(BB) == 0 && "Block already in dominator tree!");
475 DomTreeNodeBase<NodeT> *IDomNode = getNode(DomBB);
476 assert(IDomNode && "Not immediate dominator specified for block!");
477 DFSInfoValid = false;
478 return DomTreeNodes[BB] =
479 IDomNode->addChild(new DomTreeNodeBase<NodeT>(BB, IDomNode));
482 /// changeImmediateDominator - This method is used to update the dominator
483 /// tree information when a node's immediate dominator changes.
485 void changeImmediateDominator(DomTreeNodeBase<NodeT> *N,
486 DomTreeNodeBase<NodeT> *NewIDom) {
487 assert(N && NewIDom && "Cannot change null node pointers!");
488 DFSInfoValid = false;
492 void changeImmediateDominator(NodeT *BB, NodeT *NewBB) {
493 changeImmediateDominator(getNode(BB), getNode(NewBB));
496 /// eraseNode - Removes a node from the dominator tree. Block must not
497 /// domiante any other blocks. Removes node from its immediate dominator's
498 /// children list. Deletes dominator node associated with basic block BB.
499 void eraseNode(NodeT *BB) {
500 DomTreeNodeBase<NodeT> *Node = getNode(BB);
501 assert (Node && "Removing node that isn't in dominator tree.");
502 assert (Node->getChildren().empty() && "Node is not a leaf node.");
504 // Remove node from immediate dominator's children list.
505 DomTreeNodeBase<NodeT> *IDom = Node->getIDom();
507 typename std::vector<DomTreeNodeBase<NodeT>*>::iterator I =
508 std::find(IDom->Children.begin(), IDom->Children.end(), Node);
509 assert(I != IDom->Children.end() &&
510 "Not in immediate dominator children set!");
511 // I am no longer your child...
512 IDom->Children.erase(I);
515 DomTreeNodes.erase(BB);
519 /// removeNode - Removes a node from the dominator tree. Block must not
520 /// dominate any other blocks. Invalidates any node pointing to removed
522 void removeNode(NodeT *BB) {
523 assert(getNode(BB) && "Removing node that isn't in dominator tree.");
524 DomTreeNodes.erase(BB);
527 /// splitBlock - BB is split and now it has one successor. Update dominator
528 /// tree to reflect this change.
529 void splitBlock(NodeT* NewBB) {
530 if (this->IsPostDominators)
531 this->Split<Inverse<NodeT*>, GraphTraits<Inverse<NodeT*> > >(*this, NewBB);
533 this->Split<NodeT*, GraphTraits<NodeT*> >(*this, NewBB);
536 /// print - Convert to human readable form
538 void print(raw_ostream &o) const {
539 o << "=============================--------------------------------\n";
540 if (this->isPostDominator())
541 o << "Inorder PostDominator Tree: ";
543 o << "Inorder Dominator Tree: ";
544 if (this->DFSInfoValid)
545 o << "DFSNumbers invalid: " << SlowQueries << " slow queries.";
548 PrintDomTree<NodeT>(getRootNode(), o, 1);
552 template<class GraphT>
553 friend void Compress(DominatorTreeBase<typename GraphT::NodeType>& DT,
554 typename GraphT::NodeType* VIn);
556 template<class GraphT>
557 friend typename GraphT::NodeType* Eval(
558 DominatorTreeBase<typename GraphT::NodeType>& DT,
559 typename GraphT::NodeType* V);
561 template<class GraphT>
562 friend void Link(DominatorTreeBase<typename GraphT::NodeType>& DT,
563 unsigned DFSNumV, typename GraphT::NodeType* W,
564 typename DominatorTreeBase<typename GraphT::NodeType>::InfoRec &WInfo);
566 template<class GraphT>
567 friend unsigned DFSPass(DominatorTreeBase<typename GraphT::NodeType>& DT,
568 typename GraphT::NodeType* V,
571 template<class FuncT, class N>
572 friend void Calculate(DominatorTreeBase<typename GraphTraits<N>::NodeType>& DT,
575 /// updateDFSNumbers - Assign In and Out numbers to the nodes while walking
576 /// dominator tree in dfs order.
577 void updateDFSNumbers() {
580 SmallVector<std::pair<DomTreeNodeBase<NodeT>*,
581 typename DomTreeNodeBase<NodeT>::iterator>, 32> WorkStack;
583 for (unsigned i = 0, e = (unsigned)this->Roots.size(); i != e; ++i) {
584 DomTreeNodeBase<NodeT> *ThisRoot = getNode(this->Roots[i]);
585 WorkStack.push_back(std::make_pair(ThisRoot, ThisRoot->begin()));
586 ThisRoot->DFSNumIn = DFSNum++;
588 while (!WorkStack.empty()) {
589 DomTreeNodeBase<NodeT> *Node = WorkStack.back().first;
590 typename DomTreeNodeBase<NodeT>::iterator ChildIt =
591 WorkStack.back().second;
593 // If we visited all of the children of this node, "recurse" back up the
594 // stack setting the DFOutNum.
595 if (ChildIt == Node->end()) {
596 Node->DFSNumOut = DFSNum++;
597 WorkStack.pop_back();
599 // Otherwise, recursively visit this child.
600 DomTreeNodeBase<NodeT> *Child = *ChildIt;
601 ++WorkStack.back().second;
603 WorkStack.push_back(std::make_pair(Child, Child->begin()));
604 Child->DFSNumIn = DFSNum++;
613 DomTreeNodeBase<NodeT> *getNodeForBlock(NodeT *BB) {
614 typename DomTreeNodeMapType::iterator I = this->DomTreeNodes.find(BB);
615 if (I != this->DomTreeNodes.end() && I->second)
618 // Haven't calculated this node yet? Get or calculate the node for the
619 // immediate dominator.
620 NodeT *IDom = getIDom(BB);
622 assert(IDom || this->DomTreeNodes[NULL]);
623 DomTreeNodeBase<NodeT> *IDomNode = getNodeForBlock(IDom);
625 // Add a new tree node for this BasicBlock, and link it as a child of
627 DomTreeNodeBase<NodeT> *C = new DomTreeNodeBase<NodeT>(BB, IDomNode);
628 return this->DomTreeNodes[BB] = IDomNode->addChild(C);
631 inline NodeT *getIDom(NodeT *BB) const {
632 typename DenseMap<NodeT*, NodeT*>::const_iterator I = IDoms.find(BB);
633 return I != IDoms.end() ? I->second : 0;
636 inline void addRoot(NodeT* BB) {
637 this->Roots.push_back(BB);
641 /// recalculate - compute a dominator tree for the given function
643 void recalculate(FT& F) {
644 if (!this->IsPostDominators) {
648 this->Roots.push_back(&F.front());
649 this->IDoms[&F.front()] = 0;
650 this->DomTreeNodes[&F.front()] = 0;
651 this->Vertex.push_back(0);
653 Calculate<FT, NodeT*>(*this, F);
657 reset(); // Reset from the last time we were run...
659 // Initialize the roots list
660 for (typename FT::iterator I = F.begin(), E = F.end(); I != E; ++I) {
661 if (std::distance(GraphTraits<FT*>::child_begin(I),
662 GraphTraits<FT*>::child_end(I)) == 0)
665 // Prepopulate maps so that we don't get iterator invalidation issues later.
667 this->DomTreeNodes[I] = 0;
670 this->Vertex.push_back(0);
672 Calculate<FT, Inverse<NodeT*> >(*this, F);
677 EXTERN_TEMPLATE_INSTANTIATION(class DominatorTreeBase<BasicBlock>);
679 //===-------------------------------------
680 /// DominatorTree Class - Concrete subclass of DominatorTreeBase that is used to
681 /// compute a normal dominator tree.
683 class DominatorTree : public FunctionPass {
685 static char ID; // Pass ID, replacement for typeid
686 DominatorTreeBase<BasicBlock>* DT;
688 DominatorTree() : FunctionPass(&ID) {
689 DT = new DominatorTreeBase<BasicBlock>(false);
697 DominatorTreeBase<BasicBlock>& getBase() { return *DT; }
699 /// getRoots - Return the root blocks of the current CFG. This may include
700 /// multiple blocks if we are computing post dominators. For forward
701 /// dominators, this will always be a single block (the entry node).
703 inline const std::vector<BasicBlock*> &getRoots() const {
704 return DT->getRoots();
707 inline BasicBlock *getRoot() const {
708 return DT->getRoot();
711 inline DomTreeNode *getRootNode() const {
712 return DT->getRootNode();
715 /// compare - Return false if the other dominator tree matches this
716 /// dominator tree. Otherwise return true.
717 inline bool compare(DominatorTree &Other) const {
718 DomTreeNode *R = getRootNode();
719 DomTreeNode *OtherR = Other.getRootNode();
721 if (!R || !OtherR || R->getBlock() != OtherR->getBlock())
724 if (DT->compare(Other.getBase()))
730 virtual bool runOnFunction(Function &F);
732 virtual void getAnalysisUsage(AnalysisUsage &AU) const {
733 AU.setPreservesAll();
736 inline bool dominates(DomTreeNode* A, DomTreeNode* B) const {
737 return DT->dominates(A, B);
740 inline bool dominates(BasicBlock* A, BasicBlock* B) const {
741 return DT->dominates(A, B);
744 // dominates - Return true if A dominates B. This performs the
745 // special checks necessary if A and B are in the same basic block.
746 bool dominates(Instruction *A, Instruction *B) const {
747 BasicBlock *BBA = A->getParent(), *BBB = B->getParent();
748 if (BBA != BBB) return DT->dominates(BBA, BBB);
750 // It is not possible to determine dominance between two PHI nodes
751 // based on their ordering.
752 if (isa<PHINode>(A) && isa<PHINode>(B))
755 // Loop through the basic block until we find A or B.
756 BasicBlock::iterator I = BBA->begin();
757 for (; &*I != A && &*I != B; ++I) /*empty*/;
759 //if(!DT.IsPostDominators) {
760 // A dominates B if it is found first in the basic block.
763 // // A post-dominates B if B is found first in the basic block.
768 inline bool properlyDominates(const DomTreeNode* A, DomTreeNode* B) const {
769 return DT->properlyDominates(A, B);
772 inline bool properlyDominates(BasicBlock* A, BasicBlock* B) const {
773 return DT->properlyDominates(A, B);
776 /// findNearestCommonDominator - Find nearest common dominator basic block
777 /// for basic block A and B. If there is no such block then return NULL.
778 inline BasicBlock *findNearestCommonDominator(BasicBlock *A, BasicBlock *B) {
779 return DT->findNearestCommonDominator(A, B);
782 inline DomTreeNode *operator[](BasicBlock *BB) const {
783 return DT->getNode(BB);
786 /// getNode - return the (Post)DominatorTree node for the specified basic
787 /// block. This is the same as using operator[] on this class.
789 inline DomTreeNode *getNode(BasicBlock *BB) const {
790 return DT->getNode(BB);
793 /// addNewBlock - Add a new node to the dominator tree information. This
794 /// creates a new node as a child of DomBB dominator node,linking it into
795 /// the children list of the immediate dominator.
796 inline DomTreeNode *addNewBlock(BasicBlock *BB, BasicBlock *DomBB) {
797 return DT->addNewBlock(BB, DomBB);
800 /// changeImmediateDominator - This method is used to update the dominator
801 /// tree information when a node's immediate dominator changes.
803 inline void changeImmediateDominator(BasicBlock *N, BasicBlock* NewIDom) {
804 DT->changeImmediateDominator(N, NewIDom);
807 inline void changeImmediateDominator(DomTreeNode *N, DomTreeNode* NewIDom) {
808 DT->changeImmediateDominator(N, NewIDom);
811 /// eraseNode - Removes a node from the dominator tree. Block must not
812 /// domiante any other blocks. Removes node from its immediate dominator's
813 /// children list. Deletes dominator node associated with basic block BB.
814 inline void eraseNode(BasicBlock *BB) {
818 /// splitBlock - BB is split and now it has one successor. Update dominator
819 /// tree to reflect this change.
820 inline void splitBlock(BasicBlock* NewBB) {
821 DT->splitBlock(NewBB);
824 bool isReachableFromEntry(BasicBlock* A) {
825 return DT->isReachableFromEntry(A);
829 virtual void releaseMemory() {
833 virtual void print(std::ostream &OS, const Module* M= 0) const;
836 //===-------------------------------------
837 /// DominatorTree GraphTraits specialization so the DominatorTree can be
838 /// iterable by generic graph iterators.
840 template <> struct GraphTraits<DomTreeNode *> {
841 typedef DomTreeNode NodeType;
842 typedef NodeType::iterator ChildIteratorType;
844 static NodeType *getEntryNode(NodeType *N) {
847 static inline ChildIteratorType child_begin(NodeType* N) {
850 static inline ChildIteratorType child_end(NodeType* N) {
855 template <> struct GraphTraits<DominatorTree*>
856 : public GraphTraits<DomTreeNode *> {
857 static NodeType *getEntryNode(DominatorTree *DT) {
858 return DT->getRootNode();
863 //===----------------------------------------------------------------------===//
864 /// DominanceFrontierBase - Common base class for computing forward and inverse
865 /// dominance frontiers for a function.
867 class DominanceFrontierBase : public FunctionPass {
869 typedef std::set<BasicBlock*> DomSetType; // Dom set for a bb
870 typedef std::map<BasicBlock*, DomSetType> DomSetMapType; // Dom set map
872 DomSetMapType Frontiers;
873 std::vector<BasicBlock*> Roots;
874 const bool IsPostDominators;
877 DominanceFrontierBase(void *ID, bool isPostDom)
878 : FunctionPass(ID), IsPostDominators(isPostDom) {}
880 /// getRoots - Return the root blocks of the current CFG. This may include
881 /// multiple blocks if we are computing post dominators. For forward
882 /// dominators, this will always be a single block (the entry node).
884 inline const std::vector<BasicBlock*> &getRoots() const { return Roots; }
886 /// isPostDominator - Returns true if analysis based of postdoms
888 bool isPostDominator() const { return IsPostDominators; }
890 virtual void releaseMemory() { Frontiers.clear(); }
892 // Accessor interface:
893 typedef DomSetMapType::iterator iterator;
894 typedef DomSetMapType::const_iterator const_iterator;
895 iterator begin() { return Frontiers.begin(); }
896 const_iterator begin() const { return Frontiers.begin(); }
897 iterator end() { return Frontiers.end(); }
898 const_iterator end() const { return Frontiers.end(); }
899 iterator find(BasicBlock *B) { return Frontiers.find(B); }
900 const_iterator find(BasicBlock *B) const { return Frontiers.find(B); }
902 void addBasicBlock(BasicBlock *BB, const DomSetType &frontier) {
903 assert(find(BB) == end() && "Block already in DominanceFrontier!");
904 Frontiers.insert(std::make_pair(BB, frontier));
907 /// removeBlock - Remove basic block BB's frontier.
908 void removeBlock(BasicBlock *BB) {
909 assert(find(BB) != end() && "Block is not in DominanceFrontier!");
910 for (iterator I = begin(), E = end(); I != E; ++I)
915 void addToFrontier(iterator I, BasicBlock *Node) {
916 assert(I != end() && "BB is not in DominanceFrontier!");
917 I->second.insert(Node);
920 void removeFromFrontier(iterator I, BasicBlock *Node) {
921 assert(I != end() && "BB is not in DominanceFrontier!");
922 assert(I->second.count(Node) && "Node is not in DominanceFrontier of BB");
923 I->second.erase(Node);
926 /// compareDomSet - Return false if two domsets match. Otherwise
928 bool compareDomSet(DomSetType &DS1, const DomSetType &DS2) const {
929 std::set<BasicBlock *> tmpSet;
930 for (DomSetType::const_iterator I = DS2.begin(),
931 E = DS2.end(); I != E; ++I)
934 for (DomSetType::const_iterator I = DS1.begin(),
935 E = DS1.end(); I != E; ) {
936 BasicBlock *Node = *I++;
938 if (tmpSet.erase(Node) == 0)
939 // Node is in DS1 but not in DS2.
944 // There are nodes that are in DS2 but not in DS1.
947 // DS1 and DS2 matches.
951 /// compare - Return true if the other dominance frontier base matches
952 /// this dominance frontier base. Otherwise return false.
953 bool compare(DominanceFrontierBase &Other) const {
954 DomSetMapType tmpFrontiers;
955 for (DomSetMapType::const_iterator I = Other.begin(),
956 E = Other.end(); I != E; ++I)
957 tmpFrontiers.insert(std::make_pair(I->first, I->second));
959 for (DomSetMapType::iterator I = tmpFrontiers.begin(),
960 E = tmpFrontiers.end(); I != E; ) {
961 BasicBlock *Node = I->first;
962 const_iterator DFI = find(Node);
966 if (compareDomSet(I->second, DFI->second))
970 tmpFrontiers.erase(Node);
973 if (!tmpFrontiers.empty())
979 /// print - Convert to human readable form
981 virtual void print(std::ostream &OS, const Module* = 0) const;
985 //===-------------------------------------
986 /// DominanceFrontier Class - Concrete subclass of DominanceFrontierBase that is
987 /// used to compute a forward dominator frontiers.
989 class DominanceFrontier : public DominanceFrontierBase {
991 static char ID; // Pass ID, replacement for typeid
992 DominanceFrontier() :
993 DominanceFrontierBase(&ID, false) {}
995 BasicBlock *getRoot() const {
996 assert(Roots.size() == 1 && "Should always have entry node!");
1000 virtual bool runOnFunction(Function &) {
1002 DominatorTree &DT = getAnalysis<DominatorTree>();
1003 Roots = DT.getRoots();
1004 assert(Roots.size() == 1 && "Only one entry block for forward domfronts!");
1005 calculate(DT, DT[Roots[0]]);
1009 virtual void getAnalysisUsage(AnalysisUsage &AU) const {
1010 AU.setPreservesAll();
1011 AU.addRequired<DominatorTree>();
1014 /// splitBlock - BB is split and now it has one successor. Update dominance
1015 /// frontier to reflect this change.
1016 void splitBlock(BasicBlock *BB);
1018 /// BasicBlock BB's new dominator is NewBB. Update BB's dominance frontier
1019 /// to reflect this change.
1020 void changeImmediateDominator(BasicBlock *BB, BasicBlock *NewBB,
1021 DominatorTree *DT) {
1022 // NewBB is now dominating BB. Which means BB's dominance
1023 // frontier is now part of NewBB's dominance frontier. However, BB
1024 // itself is not member of NewBB's dominance frontier.
1025 DominanceFrontier::iterator NewDFI = find(NewBB);
1026 DominanceFrontier::iterator DFI = find(BB);
1027 // If BB was an entry block then its frontier is empty.
1030 DominanceFrontier::DomSetType BBSet = DFI->second;
1031 for (DominanceFrontier::DomSetType::iterator BBSetI = BBSet.begin(),
1032 BBSetE = BBSet.end(); BBSetI != BBSetE; ++BBSetI) {
1033 BasicBlock *DFMember = *BBSetI;
1034 // Insert only if NewBB dominates DFMember.
1035 if (!DT->dominates(NewBB, DFMember))
1036 NewDFI->second.insert(DFMember);
1038 NewDFI->second.erase(BB);
1041 const DomSetType &calculate(const DominatorTree &DT,
1042 const DomTreeNode *Node);
1046 } // End llvm namespace