//===- llvm/Analysis/Dominators.h - Dominator Info Calculation ---*- C++ -*--=// // // This file defines the following classes: // 1. DominatorSet: Calculates the [reverse] dominator set for a method // 2. ImmediateDominators: Calculates and holds a mapping between BasicBlocks // and their immediate dominator. // 3. DominatorTree: Represent the ImmediateDominator as an explicit tree // structure. // 4. DominanceFrontier: Calculate and hold the dominance frontier for a // method. // // These data structures are listed in increasing order of complexity. It // takes longer to calculate the dominator frontier, for example, than the // ImmediateDominator mapping. // //===----------------------------------------------------------------------===// #ifndef LLVM_DOMINATORS_H #define LLVM_DOMINATORS_H #include "llvm/Pass.h" #include namespace cfg { //===----------------------------------------------------------------------===// // // DominatorBase - Base class that other, more interesting dominator analyses // inherit from. // class DominatorBase : public MethodPass { protected: BasicBlock *Root; const bool IsPostDominators; inline DominatorBase(bool isPostDom) : Root(0), IsPostDominators(isPostDom) {} public: inline const BasicBlock *getRoot() const { return Root; } inline BasicBlock *getRoot() { return Root; } // Returns true if analysis based of postdoms bool isPostDominator() const { return IsPostDominators; } }; //===----------------------------------------------------------------------===// // // DominatorSet - Maintain a set for every basic block in a // method, that represents the blocks that dominate the block. // class DominatorSet : public DominatorBase { public: typedef std::set DomSetType; // Dom set for a bb // Map of dom sets typedef std::map DomSetMapType; private: DomSetMapType Doms; void calcForwardDominatorSet(Function *F); void calcPostDominatorSet(Function *F); public: // DominatorSet ctor - Build either the dominator set or the post-dominator // set for a method... // static AnalysisID ID; // Build dominator set static AnalysisID PostDomID; // Build postdominator set DominatorSet(AnalysisID id) : DominatorBase(id == PostDomID) {} virtual bool runOnMethod(Function *F); // Accessor interface: typedef DomSetMapType::const_iterator const_iterator; typedef DomSetMapType::iterator iterator; inline const_iterator begin() const { return Doms.begin(); } inline iterator begin() { return Doms.begin(); } inline const_iterator end() const { return Doms.end(); } inline iterator end() { return Doms.end(); } inline const_iterator find(const BasicBlock* B) const { return Doms.find(B); } inline iterator find( BasicBlock* B) { return Doms.find(B); } // getDominators - Return the set of basic blocks that dominate the specified // block. // inline const DomSetType &getDominators(const BasicBlock *BB) const { const_iterator I = find(BB); assert(I != end() && "BB not in method!"); return I->second; } // dominates - Return true if A dominates B. // inline bool dominates(const BasicBlock *A, const BasicBlock *B) const { return getDominators(B).count(A) != 0; } // getAnalysisUsageInfo - This obviously provides a dominator set, but it also // uses the UnifyMethodExitNode pass if building post-dominators // virtual void getAnalysisUsageInfo(Pass::AnalysisSet &Requires, Pass::AnalysisSet &Destroyed, Pass::AnalysisSet &Provided); }; //===----------------------------------------------------------------------===// // // ImmediateDominators - Calculate the immediate dominator for each node in a // method. // class ImmediateDominators : public DominatorBase { std::map IDoms; void calcIDoms(const DominatorSet &DS); public: // ImmediateDominators ctor - Calculate the idom or post-idom mapping, // for a method... // static AnalysisID ID; // Build immediate dominators static AnalysisID PostDomID; // Build immediate postdominators ImmediateDominators(AnalysisID id) : DominatorBase(id == PostDomID) {} virtual bool runOnMethod(Function *F) { IDoms.clear(); // Reset from the last time we were run... DominatorSet *DS; if (isPostDominator()) DS = &getAnalysis(DominatorSet::PostDomID); else DS = &getAnalysis(); Root = DS->getRoot(); calcIDoms(*DS); // Can be used to make rev-idoms return false; } // Accessor interface: typedef std::map IDomMapType; typedef IDomMapType::const_iterator const_iterator; inline const_iterator begin() const { return IDoms.begin(); } inline const_iterator end() const { return IDoms.end(); } inline const_iterator find(const BasicBlock* B) const { return IDoms.find(B);} // operator[] - Return the idom for the specified basic block. The start // node returns null, because it does not have an immediate dominator. // inline const BasicBlock *operator[](const BasicBlock *BB) const { std::map::const_iterator I = IDoms.find(BB); return I != IDoms.end() ? I->second : 0; } // getAnalysisUsageInfo - This obviously provides a dominator tree, but it // can only do so with the input of dominator sets // virtual void getAnalysisUsageInfo(Pass::AnalysisSet &Requires, Pass::AnalysisSet &Destroyed, Pass::AnalysisSet &Provided) { if (isPostDominator()) { Requires.push_back(DominatorSet::PostDomID); Provided.push_back(PostDomID); } else { Requires.push_back(DominatorSet::ID); Provided.push_back(ID); } } }; //===----------------------------------------------------------------------===// // // DominatorTree - Calculate the immediate dominator tree for a method. // class DominatorTree : public DominatorBase { class Node2; public: typedef Node2 Node; private: std::map Nodes; void calculate(const DominatorSet &DS); void reset(); typedef std::map NodeMapType; public: class Node2 : public std::vector { friend class DominatorTree; const BasicBlock *TheNode; Node2 * const IDom; public: inline const BasicBlock *getNode() const { return TheNode; } inline Node2 *getIDom() const { return IDom; } inline const std::vector &getChildren() const { return *this; } // dominates - Returns true iff this dominates N. Note that this is not a // constant time operation! inline bool dominates(const Node2 *N) const { const Node2 *IDom; while ((IDom = N->getIDom()) != 0 && IDom != this) N = IDom; // Walk up the tree return IDom != 0; } private: inline Node2(const BasicBlock *node, Node *iDom) : TheNode(node), IDom(iDom) {} inline Node2 *addChild(Node *C) { push_back(C); return C; } }; public: // DominatorTree ctor - Compute a dominator tree, given various amounts of // previous knowledge... static AnalysisID ID; // Build dominator tree static AnalysisID PostDomID; // Build postdominator tree DominatorTree(AnalysisID id) : DominatorBase(id == PostDomID) {} ~DominatorTree() { reset(); } virtual bool runOnMethod(Function *F) { reset(); DominatorSet *DS; if (isPostDominator()) DS = &getAnalysis(DominatorSet::PostDomID); else DS = &getAnalysis(); Root = DS->getRoot(); calculate(*DS); // Can be used to make rev-idoms return false; } inline const Node *operator[](const BasicBlock *BB) const { NodeMapType::const_iterator i = Nodes.find(BB); return (i != Nodes.end()) ? i->second : 0; } // getAnalysisUsageInfo - This obviously provides a dominator tree, but it // uses dominator sets // virtual void getAnalysisUsageInfo(Pass::AnalysisSet &Requires, Pass::AnalysisSet &Destroyed, Pass::AnalysisSet &Provided) { if (isPostDominator()) { Requires.push_back(DominatorSet::PostDomID); Provided.push_back(PostDomID); } else { Requires.push_back(DominatorSet::ID); Provided.push_back(ID); } } }; //===----------------------------------------------------------------------===// // // DominanceFrontier - Calculate the dominance frontiers for a method. // class DominanceFrontier : public DominatorBase { public: typedef std::set DomSetType; // Dom set for a bb typedef std::map DomSetMapType; // Dom set map private: DomSetMapType Frontiers; const DomSetType &calcDomFrontier(const DominatorTree &DT, const DominatorTree::Node *Node); const DomSetType &calcPostDomFrontier(const DominatorTree &DT, const DominatorTree::Node *Node); public: // DominatorFrontier ctor - Compute dominator frontiers for a method // static AnalysisID ID; // Build dominator frontier static AnalysisID PostDomID; // Build postdominator frontier DominanceFrontier(AnalysisID id) : DominatorBase(id == PostDomID) {} virtual bool runOnMethod(Function *) { Frontiers.clear(); DominatorTree *DT; if (isPostDominator()) DT = &getAnalysis(DominatorTree::PostDomID); else DT = &getAnalysis(); Root = DT->getRoot(); if (isPostDominator()) calcPostDomFrontier(*DT, (*DT)[Root]); else calcDomFrontier(*DT, (*DT)[Root]); return false; } // Accessor interface: typedef DomSetMapType::const_iterator const_iterator; inline const_iterator begin() const { return Frontiers.begin(); } inline const_iterator end() const { return Frontiers.end(); } inline const_iterator find(const BasicBlock* B) const { return Frontiers.find(B); } // getAnalysisUsageInfo - This obviously provides a dominator tree, but it // uses dominator sets // virtual void getAnalysisUsageInfo(Pass::AnalysisSet &Requires, Pass::AnalysisSet &Destroyed, Pass::AnalysisSet &Provided) { if (isPostDominator()) { Requires.push_back(DominatorTree::PostDomID); Provided.push_back(PostDomID); } else { Requires.push_back(DominatorTree::ID); Provided.push_back(ID); } } }; } // End namespace cfg #endif