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/Function.h"
26 #include "llvm/Instructions.h"
27 #include "llvm/ADT/DenseMap.h"
28 #include "llvm/ADT/DepthFirstIterator.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 InfoRec() : DFSNum(0), Semi(0), Size(0), Label(0), Child(0), Parent(0),
217 DenseMap<NodeT*, NodeT*> IDoms;
219 // Vertex - Map the DFS number to the BasicBlock*
220 std::vector<NodeT*> Vertex;
222 // Info - Collection of information used during the computation of idoms.
223 DenseMap<NodeT*, InfoRec> Info;
226 for (typename DomTreeNodeMapType::iterator I = this->DomTreeNodes.begin(),
227 E = DomTreeNodes.end(); I != E; ++I)
229 DomTreeNodes.clear();
236 // NewBB is split and now it has one successor. Update dominator tree to
237 // reflect this change.
238 template<class N, class GraphT>
239 void Split(DominatorTreeBase<typename GraphT::NodeType>& DT,
240 typename GraphT::NodeType* NewBB) {
241 assert(std::distance(GraphT::child_begin(NewBB),
242 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 typedef GraphTraits<Inverse<N> > InvTraits;
248 for (typename InvTraits::ChildIteratorType PI =
249 InvTraits::child_begin(NewBB),
250 PE = InvTraits::child_end(NewBB); PI != PE; ++PI)
251 PredBlocks.push_back(*PI);
253 assert(!PredBlocks.empty() && "No predblocks?");
255 bool NewBBDominatesNewBBSucc = true;
256 for (typename InvTraits::ChildIteratorType PI =
257 InvTraits::child_begin(NewBBSucc),
258 E = InvTraits::child_end(NewBBSucc); PI != E; ++PI) {
259 typename InvTraits::NodeType *ND = *PI;
260 if (ND != NewBB && !DT.dominates(NewBBSucc, ND) &&
261 DT.isReachableFromEntry(ND)) {
262 NewBBDominatesNewBBSucc = false;
267 // Find NewBB's immediate dominator and create new dominator tree node for
269 NodeT *NewBBIDom = 0;
271 for (i = 0; i < PredBlocks.size(); ++i)
272 if (DT.isReachableFromEntry(PredBlocks[i])) {
273 NewBBIDom = PredBlocks[i];
277 // It's possible that none of the predecessors of NewBB are reachable;
278 // in that case, NewBB itself is unreachable, so nothing needs to be
283 for (i = i + 1; i < PredBlocks.size(); ++i) {
284 if (DT.isReachableFromEntry(PredBlocks[i]))
285 NewBBIDom = DT.findNearestCommonDominator(NewBBIDom, PredBlocks[i]);
288 // Create the new dominator tree node... and set the idom of NewBB.
289 DomTreeNodeBase<NodeT> *NewBBNode = DT.addNewBlock(NewBB, NewBBIDom);
291 // If NewBB strictly dominates other blocks, then it is now the immediate
292 // dominator of NewBBSucc. Update the dominator tree as appropriate.
293 if (NewBBDominatesNewBBSucc) {
294 DomTreeNodeBase<NodeT> *NewBBSuccNode = DT.getNode(NewBBSucc);
295 DT.changeImmediateDominator(NewBBSuccNode, NewBBNode);
300 explicit DominatorTreeBase(bool isPostDom)
301 : DominatorBase<NodeT>(isPostDom), DFSInfoValid(false), SlowQueries(0) {}
302 virtual ~DominatorTreeBase() { reset(); }
304 // FIXME: Should remove this
305 virtual bool runOnFunction(Function &F) { return false; }
307 /// compare - Return false if the other dominator tree base matches this
308 /// dominator tree base. Otherwise return true.
309 bool compare(DominatorTreeBase &Other) const {
311 const DomTreeNodeMapType &OtherDomTreeNodes = Other.DomTreeNodes;
312 if (DomTreeNodes.size() != OtherDomTreeNodes.size())
315 for (typename DomTreeNodeMapType::const_iterator
316 I = this->DomTreeNodes.begin(),
317 E = this->DomTreeNodes.end(); I != E; ++I) {
318 NodeT *BB = I->first;
319 typename DomTreeNodeMapType::const_iterator OI = OtherDomTreeNodes.find(BB);
320 if (OI == OtherDomTreeNodes.end())
323 DomTreeNodeBase<NodeT>* MyNd = I->second;
324 DomTreeNodeBase<NodeT>* OtherNd = OI->second;
326 if (MyNd->compare(OtherNd))
333 virtual void releaseMemory() { reset(); }
335 /// getNode - return the (Post)DominatorTree node for the specified basic
336 /// block. This is the same as using operator[] on this class.
338 inline DomTreeNodeBase<NodeT> *getNode(NodeT *BB) const {
339 typename DomTreeNodeMapType::const_iterator I = DomTreeNodes.find(BB);
340 return I != DomTreeNodes.end() ? I->second : 0;
343 /// getRootNode - This returns the entry node for the CFG of the function. If
344 /// this tree represents the post-dominance relations for a function, however,
345 /// this root may be a node with the block == NULL. This is the case when
346 /// there are multiple exit nodes from a particular function. Consumers of
347 /// post-dominance information must be capable of dealing with this
350 DomTreeNodeBase<NodeT> *getRootNode() { return RootNode; }
351 const DomTreeNodeBase<NodeT> *getRootNode() const { return RootNode; }
353 /// properlyDominates - Returns true iff this dominates N and this != N.
354 /// Note that this is not a constant time operation!
356 bool properlyDominates(const DomTreeNodeBase<NodeT> *A,
357 const DomTreeNodeBase<NodeT> *B) const {
358 if (A == 0 || B == 0) return false;
359 return dominatedBySlowTreeWalk(A, B);
362 inline bool properlyDominates(const NodeT *A, const NodeT *B) {
366 // Cast away the const qualifiers here. This is ok since
367 // this function doesn't actually return the values returned
369 return properlyDominates(getNode(const_cast<NodeT *>(A)),
370 getNode(const_cast<NodeT *>(B)));
373 bool dominatedBySlowTreeWalk(const DomTreeNodeBase<NodeT> *A,
374 const DomTreeNodeBase<NodeT> *B) const {
375 const DomTreeNodeBase<NodeT> *IDom;
376 if (A == 0 || B == 0) return false;
377 while ((IDom = B->getIDom()) != 0 && IDom != A && IDom != B)
378 B = IDom; // Walk up the tree
383 /// isReachableFromEntry - Return true if A is dominated by the entry
384 /// block of the function containing it.
385 bool isReachableFromEntry(const NodeT* A) {
386 assert(!this->isPostDominator() &&
387 "This is not implemented for post dominators");
388 return dominates(&A->getParent()->front(), A);
391 /// dominates - Returns true iff A dominates B. Note that this is not a
392 /// constant time operation!
394 inline bool dominates(const DomTreeNodeBase<NodeT> *A,
395 const DomTreeNodeBase<NodeT> *B) {
397 return true; // A node trivially dominates itself.
399 if (A == 0 || B == 0)
402 // Compare the result of the tree walk and the dfs numbers, if expensive
403 // checks are enabled.
405 assert((!DFSInfoValid ||
406 (dominatedBySlowTreeWalk(A, B) == B->DominatedBy(A))) &&
407 "Tree walk disagrees with dfs numbers!");
411 return B->DominatedBy(A);
413 // If we end up with too many slow queries, just update the
414 // DFS numbers on the theory that we are going to keep querying.
416 if (SlowQueries > 32) {
418 return B->DominatedBy(A);
421 return dominatedBySlowTreeWalk(A, B);
424 inline bool dominates(const NodeT *A, const NodeT *B) {
428 // Cast away the const qualifiers here. This is ok since
429 // this function doesn't actually return the values returned
431 return dominates(getNode(const_cast<NodeT *>(A)),
432 getNode(const_cast<NodeT *>(B)));
435 NodeT *getRoot() const {
436 assert(this->Roots.size() == 1 && "Should always have entry node!");
437 return this->Roots[0];
440 /// findNearestCommonDominator - Find nearest common dominator basic block
441 /// for basic block A and B. If there is no such block then return NULL.
442 NodeT *findNearestCommonDominator(NodeT *A, NodeT *B) {
443 assert(A->getParent() == B->getParent() &&
444 "Two blocks are not in same function");
446 // If either A or B is a entry block then it is nearest common dominator
447 // (for forward-dominators).
448 if (!this->isPostDominator()) {
449 NodeT &Entry = A->getParent()->front();
450 if (A == &Entry || B == &Entry)
454 // If B dominates A then B is nearest common dominator.
458 // If A dominates B then A is nearest common dominator.
462 DomTreeNodeBase<NodeT> *NodeA = getNode(A);
463 DomTreeNodeBase<NodeT> *NodeB = getNode(B);
465 // Collect NodeA dominators set.
466 SmallPtrSet<DomTreeNodeBase<NodeT>*, 16> NodeADoms;
467 NodeADoms.insert(NodeA);
468 DomTreeNodeBase<NodeT> *IDomA = NodeA->getIDom();
470 NodeADoms.insert(IDomA);
471 IDomA = IDomA->getIDom();
474 // Walk NodeB immediate dominators chain and find common dominator node.
475 DomTreeNodeBase<NodeT> *IDomB = NodeB->getIDom();
477 if (NodeADoms.count(IDomB) != 0)
478 return IDomB->getBlock();
480 IDomB = IDomB->getIDom();
486 const NodeT *findNearestCommonDominator(const NodeT *A, const NodeT *B) {
487 // Cast away the const qualifiers here. This is ok since
488 // const is re-introduced on the return type.
489 return findNearestCommonDominator(const_cast<NodeT *>(A),
490 const_cast<NodeT *>(B));
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 /// dominate 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 void print(raw_ostream &o) 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 // The postdom tree can have a null root if there are no returns.
577 PrintDomTree<NodeT>(getRootNode(), o, 1);
581 template<class GraphT>
582 friend void Compress(DominatorTreeBase<typename GraphT::NodeType>& DT,
583 typename GraphT::NodeType* VIn);
585 template<class GraphT>
586 friend typename GraphT::NodeType* Eval(
587 DominatorTreeBase<typename GraphT::NodeType>& DT,
588 typename GraphT::NodeType* V);
590 template<class GraphT>
591 friend void Link(DominatorTreeBase<typename GraphT::NodeType>& DT,
592 unsigned DFSNumV, typename GraphT::NodeType* W,
593 typename DominatorTreeBase<typename GraphT::NodeType>::InfoRec &WInfo);
595 template<class GraphT>
596 friend unsigned DFSPass(DominatorTreeBase<typename GraphT::NodeType>& DT,
597 typename GraphT::NodeType* V,
600 template<class FuncT, class N>
601 friend void Calculate(DominatorTreeBase<typename GraphTraits<N>::NodeType>& DT,
604 /// updateDFSNumbers - Assign In and Out numbers to the nodes while walking
605 /// dominator tree in dfs order.
606 void updateDFSNumbers() {
609 SmallVector<std::pair<DomTreeNodeBase<NodeT>*,
610 typename DomTreeNodeBase<NodeT>::iterator>, 32> WorkStack;
612 DomTreeNodeBase<NodeT> *ThisRoot = getRootNode();
617 // Even in the case of multiple exits that form the post dominator root
618 // nodes, do not iterate over all exits, but start from the virtual root
619 // node. Otherwise bbs, that are not post dominated by any exit but by the
620 // virtual root node, will never be assigned a DFS number.
621 WorkStack.push_back(std::make_pair(ThisRoot, ThisRoot->begin()));
622 ThisRoot->DFSNumIn = DFSNum++;
624 while (!WorkStack.empty()) {
625 DomTreeNodeBase<NodeT> *Node = WorkStack.back().first;
626 typename DomTreeNodeBase<NodeT>::iterator ChildIt =
627 WorkStack.back().second;
629 // If we visited all of the children of this node, "recurse" back up the
630 // stack setting the DFOutNum.
631 if (ChildIt == Node->end()) {
632 Node->DFSNumOut = DFSNum++;
633 WorkStack.pop_back();
635 // Otherwise, recursively visit this child.
636 DomTreeNodeBase<NodeT> *Child = *ChildIt;
637 ++WorkStack.back().second;
639 WorkStack.push_back(std::make_pair(Child, Child->begin()));
640 Child->DFSNumIn = DFSNum++;
648 DomTreeNodeBase<NodeT> *getNodeForBlock(NodeT *BB) {
649 typename DomTreeNodeMapType::iterator I = this->DomTreeNodes.find(BB);
650 if (I != this->DomTreeNodes.end() && I->second)
653 // Haven't calculated this node yet? Get or calculate the node for the
654 // immediate dominator.
655 NodeT *IDom = getIDom(BB);
657 assert(IDom || this->DomTreeNodes[NULL]);
658 DomTreeNodeBase<NodeT> *IDomNode = getNodeForBlock(IDom);
660 // Add a new tree node for this BasicBlock, and link it as a child of
662 DomTreeNodeBase<NodeT> *C = new DomTreeNodeBase<NodeT>(BB, IDomNode);
663 return this->DomTreeNodes[BB] = IDomNode->addChild(C);
666 inline NodeT *getIDom(NodeT *BB) const {
667 typename DenseMap<NodeT*, NodeT*>::const_iterator I = IDoms.find(BB);
668 return I != IDoms.end() ? I->second : 0;
671 inline void addRoot(NodeT* BB) {
672 this->Roots.push_back(BB);
676 /// recalculate - compute a dominator tree for the given function
678 void recalculate(FT& F) {
680 this->Vertex.push_back(0);
682 if (!this->IsPostDominators) {
684 this->Roots.push_back(&F.front());
685 this->IDoms[&F.front()] = 0;
686 this->DomTreeNodes[&F.front()] = 0;
688 Calculate<FT, NodeT*>(*this, F);
690 // Initialize the roots list
691 for (typename FT::iterator I = F.begin(), E = F.end(); I != E; ++I) {
692 if (std::distance(GraphTraits<FT*>::child_begin(I),
693 GraphTraits<FT*>::child_end(I)) == 0)
696 // Prepopulate maps so that we don't get iterator invalidation issues later.
698 this->DomTreeNodes[I] = 0;
701 Calculate<FT, Inverse<NodeT*> >(*this, F);
706 EXTERN_TEMPLATE_INSTANTIATION(class DominatorTreeBase<BasicBlock>);
708 //===-------------------------------------
709 /// DominatorTree Class - Concrete subclass of DominatorTreeBase that is used to
710 /// compute a normal dominator tree.
712 class DominatorTree : public FunctionPass {
714 static char ID; // Pass ID, replacement for typeid
715 DominatorTreeBase<BasicBlock>* DT;
717 DominatorTree() : FunctionPass(ID) {
718 initializeDominatorTreePass(*PassRegistry::getPassRegistry());
719 DT = new DominatorTreeBase<BasicBlock>(false);
726 DominatorTreeBase<BasicBlock>& getBase() { return *DT; }
728 /// getRoots - Return the root blocks of the current CFG. This may include
729 /// multiple blocks if we are computing post dominators. For forward
730 /// dominators, this will always be a single block (the entry node).
732 inline const std::vector<BasicBlock*> &getRoots() const {
733 return DT->getRoots();
736 inline BasicBlock *getRoot() const {
737 return DT->getRoot();
740 inline DomTreeNode *getRootNode() const {
741 return DT->getRootNode();
744 /// compare - Return false if the other dominator tree matches this
745 /// dominator tree. Otherwise return true.
746 inline bool compare(DominatorTree &Other) const {
747 DomTreeNode *R = getRootNode();
748 DomTreeNode *OtherR = Other.getRootNode();
750 if (!R || !OtherR || R->getBlock() != OtherR->getBlock())
753 if (DT->compare(Other.getBase()))
759 virtual bool runOnFunction(Function &F);
761 virtual void verifyAnalysis() const;
763 virtual void getAnalysisUsage(AnalysisUsage &AU) const {
764 AU.setPreservesAll();
767 inline bool dominates(const DomTreeNode* A, const DomTreeNode* B) const {
768 return DT->dominates(A, B);
771 inline bool dominates(const BasicBlock* A, const BasicBlock* B) const {
772 return DT->dominates(A, B);
775 // dominates - Return true if A dominates B. This performs the
776 // special checks necessary if A and B are in the same basic block.
777 bool dominates(const Instruction *A, const Instruction *B) const;
779 bool properlyDominates(const DomTreeNode *A, const DomTreeNode *B) const {
780 return DT->properlyDominates(A, B);
783 bool properlyDominates(const BasicBlock *A, const BasicBlock *B) const {
784 return DT->properlyDominates(A, B);
787 /// findNearestCommonDominator - Find nearest common dominator basic block
788 /// for basic block A and B. If there is no such block then return NULL.
789 inline BasicBlock *findNearestCommonDominator(BasicBlock *A, BasicBlock *B) {
790 return DT->findNearestCommonDominator(A, B);
793 inline const BasicBlock *findNearestCommonDominator(const BasicBlock *A,
794 const BasicBlock *B) {
795 return DT->findNearestCommonDominator(A, B);
798 inline DomTreeNode *operator[](BasicBlock *BB) const {
799 return DT->getNode(BB);
802 /// getNode - return the (Post)DominatorTree node for the specified basic
803 /// block. This is the same as using operator[] on this class.
805 inline DomTreeNode *getNode(BasicBlock *BB) const {
806 return DT->getNode(BB);
809 /// addNewBlock - Add a new node to the dominator tree information. This
810 /// creates a new node as a child of DomBB dominator node,linking it into
811 /// the children list of the immediate dominator.
812 inline DomTreeNode *addNewBlock(BasicBlock *BB, BasicBlock *DomBB) {
813 return DT->addNewBlock(BB, DomBB);
816 /// changeImmediateDominator - This method is used to update the dominator
817 /// tree information when a node's immediate dominator changes.
819 inline void changeImmediateDominator(BasicBlock *N, BasicBlock* NewIDom) {
820 DT->changeImmediateDominator(N, NewIDom);
823 inline void changeImmediateDominator(DomTreeNode *N, DomTreeNode* NewIDom) {
824 DT->changeImmediateDominator(N, NewIDom);
827 /// eraseNode - Removes a node from the dominator tree. Block must not
828 /// dominate any other blocks. Removes node from its immediate dominator's
829 /// children list. Deletes dominator node associated with basic block BB.
830 inline void eraseNode(BasicBlock *BB) {
834 /// splitBlock - BB is split and now it has one successor. Update dominator
835 /// tree to reflect this change.
836 inline void splitBlock(BasicBlock* NewBB) {
837 DT->splitBlock(NewBB);
840 bool isReachableFromEntry(const BasicBlock* A) {
841 return DT->isReachableFromEntry(A);
845 virtual void releaseMemory() {
849 virtual void print(raw_ostream &OS, const Module* M= 0) const;
852 //===-------------------------------------
853 /// DominatorTree GraphTraits specialization so the DominatorTree can be
854 /// iterable by generic graph iterators.
856 template <> struct GraphTraits<DomTreeNode*> {
857 typedef DomTreeNode NodeType;
858 typedef NodeType::iterator ChildIteratorType;
860 static NodeType *getEntryNode(NodeType *N) {
863 static inline ChildIteratorType child_begin(NodeType *N) {
866 static inline ChildIteratorType child_end(NodeType *N) {
870 typedef df_iterator<DomTreeNode*> nodes_iterator;
872 static nodes_iterator nodes_begin(DomTreeNode *N) {
873 return df_begin(getEntryNode(N));
876 static nodes_iterator nodes_end(DomTreeNode *N) {
877 return df_end(getEntryNode(N));
881 template <> struct GraphTraits<DominatorTree*>
882 : public GraphTraits<DomTreeNode*> {
883 static NodeType *getEntryNode(DominatorTree *DT) {
884 return DT->getRootNode();
887 static nodes_iterator nodes_begin(DominatorTree *N) {
888 return df_begin(getEntryNode(N));
891 static nodes_iterator nodes_end(DominatorTree *N) {
892 return df_end(getEntryNode(N));
897 //===----------------------------------------------------------------------===//
898 /// DominanceFrontierBase - Common base class for computing forward and inverse
899 /// dominance frontiers for a function.
901 class DominanceFrontierBase : public FunctionPass {
903 typedef std::set<BasicBlock*> DomSetType; // Dom set for a bb
904 typedef std::map<BasicBlock*, DomSetType> DomSetMapType; // Dom set map
906 DomSetMapType Frontiers;
907 std::vector<BasicBlock*> Roots;
908 const bool IsPostDominators;
911 DominanceFrontierBase(char &ID, bool isPostDom)
912 : FunctionPass(ID), IsPostDominators(isPostDom) {}
914 /// getRoots - Return the root blocks of the current CFG. This may include
915 /// multiple blocks if we are computing post dominators. For forward
916 /// dominators, this will always be a single block (the entry node).
918 inline const std::vector<BasicBlock*> &getRoots() const { return Roots; }
920 /// isPostDominator - Returns true if analysis based of postdoms
922 bool isPostDominator() const { return IsPostDominators; }
924 virtual void releaseMemory() { Frontiers.clear(); }
926 // Accessor interface:
927 typedef DomSetMapType::iterator iterator;
928 typedef DomSetMapType::const_iterator const_iterator;
929 iterator begin() { return Frontiers.begin(); }
930 const_iterator begin() const { return Frontiers.begin(); }
931 iterator end() { return Frontiers.end(); }
932 const_iterator end() const { return Frontiers.end(); }
933 iterator find(BasicBlock *B) { return Frontiers.find(B); }
934 const_iterator find(BasicBlock *B) const { return Frontiers.find(B); }
936 iterator addBasicBlock(BasicBlock *BB, const DomSetType &frontier) {
937 assert(find(BB) == end() && "Block already in DominanceFrontier!");
938 return Frontiers.insert(std::make_pair(BB, frontier)).first;
941 /// removeBlock - Remove basic block BB's frontier.
942 void removeBlock(BasicBlock *BB) {
943 assert(find(BB) != end() && "Block is not in DominanceFrontier!");
944 for (iterator I = begin(), E = end(); I != E; ++I)
949 void addToFrontier(iterator I, BasicBlock *Node) {
950 assert(I != end() && "BB is not in DominanceFrontier!");
951 I->second.insert(Node);
954 void removeFromFrontier(iterator I, BasicBlock *Node) {
955 assert(I != end() && "BB is not in DominanceFrontier!");
956 assert(I->second.count(Node) && "Node is not in DominanceFrontier of BB");
957 I->second.erase(Node);
960 /// compareDomSet - Return false if two domsets match. Otherwise
962 bool compareDomSet(DomSetType &DS1, const DomSetType &DS2) const {
963 std::set<BasicBlock *> tmpSet;
964 for (DomSetType::const_iterator I = DS2.begin(),
965 E = DS2.end(); I != E; ++I)
968 for (DomSetType::const_iterator I = DS1.begin(),
969 E = DS1.end(); I != E; ) {
970 BasicBlock *Node = *I++;
972 if (tmpSet.erase(Node) == 0)
973 // Node is in DS1 but not in DS2.
978 // There are nodes that are in DS2 but not in DS1.
981 // DS1 and DS2 matches.
985 /// compare - Return true if the other dominance frontier base matches
986 /// this dominance frontier base. Otherwise return false.
987 bool compare(DominanceFrontierBase &Other) const {
988 DomSetMapType tmpFrontiers;
989 for (DomSetMapType::const_iterator I = Other.begin(),
990 E = Other.end(); I != E; ++I)
991 tmpFrontiers.insert(std::make_pair(I->first, I->second));
993 for (DomSetMapType::iterator I = tmpFrontiers.begin(),
994 E = tmpFrontiers.end(); I != E; ) {
995 BasicBlock *Node = I->first;
996 const_iterator DFI = find(Node);
1000 if (compareDomSet(I->second, DFI->second))
1004 tmpFrontiers.erase(Node);
1007 if (!tmpFrontiers.empty())
1013 /// print - Convert to human readable form
1015 virtual void print(raw_ostream &OS, const Module* = 0) const;
1017 /// dump - Dump the dominance frontier to dbgs().
1022 //===-------------------------------------
1023 /// DominanceFrontier Class - Concrete subclass of DominanceFrontierBase that is
1024 /// used to compute a forward dominator frontiers.
1026 class DominanceFrontier : public DominanceFrontierBase {
1028 static char ID; // Pass ID, replacement for typeid
1029 DominanceFrontier() :
1030 DominanceFrontierBase(ID, false) {
1031 initializeDominanceFrontierPass(*PassRegistry::getPassRegistry());
1034 BasicBlock *getRoot() const {
1035 assert(Roots.size() == 1 && "Should always have entry node!");
1039 virtual bool runOnFunction(Function &) {
1041 DominatorTree &DT = getAnalysis<DominatorTree>();
1042 Roots = DT.getRoots();
1043 assert(Roots.size() == 1 && "Only one entry block for forward domfronts!");
1044 calculate(DT, DT[Roots[0]]);
1048 virtual void verifyAnalysis() const;
1050 virtual void getAnalysisUsage(AnalysisUsage &AU) const {
1051 AU.setPreservesAll();
1052 AU.addRequired<DominatorTree>();
1055 /// splitBlock - BB is split and now it has one successor. Update dominance
1056 /// frontier to reflect this change.
1057 void splitBlock(BasicBlock *BB);
1059 /// BasicBlock BB's new dominator is NewBB. Update BB's dominance frontier
1060 /// to reflect this change.
1061 void changeImmediateDominator(BasicBlock *BB, BasicBlock *NewBB,
1062 DominatorTree *DT) {
1063 // NewBB is now dominating BB. Which means BB's dominance
1064 // frontier is now part of NewBB's dominance frontier. However, BB
1065 // itself is not member of NewBB's dominance frontier.
1066 DominanceFrontier::iterator NewDFI = find(NewBB);
1067 DominanceFrontier::iterator DFI = find(BB);
1068 // If BB was an entry block then its frontier is empty.
1071 DominanceFrontier::DomSetType BBSet = DFI->second;
1072 for (DominanceFrontier::DomSetType::iterator BBSetI = BBSet.begin(),
1073 BBSetE = BBSet.end(); BBSetI != BBSetE; ++BBSetI) {
1074 BasicBlock *DFMember = *BBSetI;
1075 // Insert only if NewBB dominates DFMember.
1076 if (!DT->dominates(NewBB, DFMember))
1077 NewDFI->second.insert(DFMember);
1079 NewDFI->second.erase(BB);
1082 const DomSetType &calculate(const DominatorTree &DT,
1083 const DomTreeNode *Node);
1087 } // End llvm namespace