-//===- llvm/Analysis/DominatorSet.h - Dominator Set Calculation --*- C++ -*--=//
+//===- llvm/Analysis/Dominators.h - Dominator Info Calculation --*- C++ -*-===//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file was developed by the LLVM research group and is distributed under
+// the University of Illinois Open Source License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
//
// 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
+// 1. DominatorTree: Represent the ImmediateDominator as an explicit tree
// structure.
-// 4. DominanceFrontier: Calculate and hold the dominance frontier for a
-// method.
+// 2. ETForest: Efficient data structure for dominance comparisons and
+// nearest-common-ancestor queries.
+// 3. DominanceFrontier: Calculate and hold the dominance frontier for a
+// function.
//
// These data structures are listed in increasing order of complexity. It
-// takes longer to calculate the dominator frontier, for example, than the
+// takes longer to calculate the dominator frontier, for example, than the
// ImmediateDominator mapping.
-//
+//
//===----------------------------------------------------------------------===//
-#ifndef LLVM_DOMINATORS_H
-#define LLVM_DOMINATORS_H
+#ifndef LLVM_ANALYSIS_DOMINATORS_H
+#define LLVM_ANALYSIS_DOMINATORS_H
+#include "llvm/Analysis/ET-Forest.h"
+#include "llvm/Pass.h"
#include <set>
-#include <map>
-#include <vector>
-class Method;
-class BasicBlock;
-namespace cfg {
+namespace llvm {
+
+class Instruction;
+
+template <typename GraphType> struct GraphTraits;
//===----------------------------------------------------------------------===//
-//
-// DominatorBase - Base class that other, more interesting dominator analyses
-// inherit from.
-//
-class DominatorBase {
+/// DominatorBase - Base class that other, more interesting dominator analyses
+/// inherit from.
+///
+class DominatorBase : public FunctionPass {
protected:
- const BasicBlock *Root;
- inline DominatorBase(const BasicBlock *root = 0) : Root(root) {}
+ std::vector<BasicBlock*> Roots;
+ const bool IsPostDominators;
+
+ inline DominatorBase(bool isPostDom) : Roots(), IsPostDominators(isPostDom) {}
public:
- inline const BasicBlock *getRoot() const { return Root; }
- bool isPostDominator() const; // Returns true if analysis based of postdoms
+ /// getRoots - Return the root blocks of the current CFG. This may include
+ /// multiple blocks if we are computing post dominators. For forward
+ /// dominators, this will always be a single block (the entry node).
+ ///
+ inline const std::vector<BasicBlock*> &getRoots() const { return Roots; }
+
+ /// isPostDominator - Returns true if analysis based of postdoms
+ ///
+ bool isPostDominator() const { return IsPostDominators; }
};
//===----------------------------------------------------------------------===//
-//
-// DominatorSet - Maintain a set<const BasicBlock*> for every basic block in a
-// method, that represents the blocks that dominate the block.
-//
-class DominatorSet : public DominatorBase {
+/// DominatorTree - Calculate the immediate dominator tree for a function.
+///
+class DominatorTreeBase : public DominatorBase {
public:
- typedef set<const BasicBlock*> DomSetType; // Dom set for a bb
- typedef map<const BasicBlock *, DomSetType> DomSetMapType; // Map of dom sets
-private:
- DomSetMapType Doms;
-
- void calcForwardDominatorSet(const Method *M);
-public:
- // DominatorSet ctor - Build either the dominator set or the post-dominator
- // set for a method... Building the postdominator set may require the analysis
- // routine to modify the method so that there is only a single return in the
- // method.
- //
- DominatorSet(const Method *M);
- DominatorSet( Method *M, bool PostDomSet);
-
- // Accessor interface:
- typedef DomSetMapType::const_iterator const_iterator;
- inline const_iterator begin() const { return Doms.begin(); }
- inline const_iterator end() const { return Doms.end(); }
- inline const_iterator find(const BasicBlock* B) const { return Doms.find(B); }
+ class Node;
+protected:
+ std::map<BasicBlock*, Node*> Nodes;
+ void reset();
+ typedef std::map<BasicBlock*, Node*> NodeMapType;
- // 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;
- }
+ Node *RootNode;
- // dominates - Return true if A dominates B.
- //
- inline bool dominates(const BasicBlock *A, const BasicBlock *B) const {
- return getDominators(B).count(A) != 0;
- }
-};
+ struct InfoRec {
+ unsigned Semi;
+ unsigned Size;
+ BasicBlock *Label, *Parent, *Child, *Ancestor;
+ std::vector<BasicBlock*> Bucket;
-//===----------------------------------------------------------------------===//
-//
-// ImmediateDominators - Calculate the immediate dominator for each node in a
-// method.
-//
-class ImmediateDominators : public DominatorBase {
- map<const BasicBlock*, const BasicBlock*> IDoms;
- void calcIDoms(const DominatorSet &DS);
-public:
+ InfoRec() : Semi(0), Size(0), Label(0), Parent(0), Child(0), Ancestor(0){}
+ };
- // ImmediateDominators ctor - Calculate the idom mapping, for a method, or
- // from a dominator set calculated for something else...
- //
- inline ImmediateDominators(const DominatorSet &DS)
- : DominatorBase(DS.getRoot()) {
- calcIDoms(DS); // Can be used to make rev-idoms
- }
+ std::map<BasicBlock*, BasicBlock*> IDoms;
- // Accessor interface:
- typedef map<const BasicBlock*, const BasicBlock*> 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 {
- map<const BasicBlock*, const BasicBlock*>::const_iterator I =
- IDoms.find(BB);
- return I != IDoms.end() ? I->second : 0;
- }
-};
+ // Vertex - Map the DFS number to the BasicBlock*
+ std::vector<BasicBlock*> Vertex;
+ // Info - Collection of information used during the computation of idoms.
+ std::map<BasicBlock*, InfoRec> Info;
-//===----------------------------------------------------------------------===//
-//
-// DominatorTree - Calculate the immediate dominator tree for a method.
-//
-class DominatorTree : public DominatorBase {
- class Node;
- map<const BasicBlock*, Node*> Nodes;
- void calculate(const DominatorSet &DS);
- typedef map<const BasicBlock*, Node*> NodeMapType;
public:
- class Node : public vector<Node*> {
+ class Node {
friend class DominatorTree;
- const BasicBlock *TheNode;
- Node * const IDom;
+ friend struct PostDominatorTree;
+ friend class DominatorTreeBase;
+ BasicBlock *TheBB;
+ Node *IDom;
+ std::vector<Node*> Children;
public:
- inline const BasicBlock *getNode() const { return TheNode; }
+ typedef std::vector<Node*>::iterator iterator;
+ typedef std::vector<Node*>::const_iterator const_iterator;
+
+ iterator begin() { return Children.begin(); }
+ iterator end() { return Children.end(); }
+ const_iterator begin() const { return Children.begin(); }
+ const_iterator end() const { return Children.end(); }
+
+ inline BasicBlock *getBlock() const { return TheBB; }
inline Node *getIDom() const { return IDom; }
- inline const vector<Node*> &getChildren() const { return *this; }
+ inline const std::vector<Node*> &getChildren() const { return Children; }
- // dominates - Returns true iff this dominates N. Note that this is not a
- // constant time operation!
- inline bool dominates(const Node *N) const {
+ /// properlyDominates - Returns true iff this dominates N and this != N.
+ /// Note that this is not a constant time operation!
+ ///
+ bool properlyDominates(const Node *N) const {
const Node *IDom;
+ if (this == 0 || N == 0) return false;
while ((IDom = N->getIDom()) != 0 && IDom != this)
- N = IDom; // Walk up the tree
+ N = IDom; // Walk up the tree
return IDom != 0;
}
+ /// dominates - Returns true iff this dominates N. Note that this is not a
+ /// constant time operation!
+ ///
+ inline bool dominates(const Node *N) const {
+ if (N == this) return true; // A node trivially dominates itself.
+ return properlyDominates(N);
+ }
+
private:
- inline Node(const BasicBlock *node, Node *iDom)
- : TheNode(node), IDom(iDom) {}
- inline Node *addChild(Node *C) { push_back(C); return C; }
+ inline Node(BasicBlock *BB, Node *iDom) : TheBB(BB), IDom(iDom) {}
+ inline Node *addChild(Node *C) { Children.push_back(C); return C; }
+
+ void setIDom(Node *NewIDom);
};
public:
- // DominatorTree ctors - Compute a dominator tree, given various amounts of
- // previous knowledge...
- inline DominatorTree(const DominatorSet &DS) : DominatorBase(DS.getRoot()) {
- calculate(DS);
- }
+ DominatorTreeBase(bool isPostDom) : DominatorBase(isPostDom) {}
+ ~DominatorTreeBase() { reset(); }
- DominatorTree(const ImmediateDominators &IDoms);
- ~DominatorTree();
+ virtual void releaseMemory() { reset(); }
- inline const Node *operator[](const BasicBlock *BB) const {
+ /// getNode - return the (Post)DominatorTree node for the specified basic
+ /// block. This is the same as using operator[] on this class.
+ ///
+ inline Node *getNode(BasicBlock *BB) const {
NodeMapType::const_iterator i = Nodes.find(BB);
return (i != Nodes.end()) ? i->second : 0;
}
+
+ inline Node *operator[](BasicBlock *BB) const {
+ return getNode(BB);
+ }
+
+ /// getRootNode - This returns the entry node for the CFG of the function. If
+ /// this tree represents the post-dominance relations for a function, however,
+ /// this root may be a node with the block == NULL. This is the case when
+ /// there are multiple exit nodes from a particular function. Consumers of
+ /// post-dominance information must be capable of dealing with this
+ /// possibility.
+ ///
+ Node *getRootNode() { return RootNode; }
+ const Node *getRootNode() const { return RootNode; }
+
+ //===--------------------------------------------------------------------===//
+ // API to update (Post)DominatorTree information based on modifications to
+ // the CFG...
+
+ /// createNewNode - Add a new node to the dominator tree information. This
+ /// creates a new node as a child of IDomNode, linking it into the children
+ /// list of the immediate dominator.
+ ///
+ Node *createNewNode(BasicBlock *BB, Node *IDomNode) {
+ assert(getNode(BB) == 0 && "Block already in dominator tree!");
+ assert(IDomNode && "Not immediate dominator specified for block!");
+ return Nodes[BB] = IDomNode->addChild(new Node(BB, IDomNode));
+ }
+
+ /// changeImmediateDominator - This method is used to update the dominator
+ /// tree information when a node's immediate dominator changes.
+ ///
+ void changeImmediateDominator(Node *N, Node *NewIDom) {
+ assert(N && NewIDom && "Cannot change null node pointers!");
+ N->setIDom(NewIDom);
+ }
+
+ /// removeNode - Removes a node from the dominator tree. Block must not
+ /// dominate any other blocks. Invalidates any node pointing to removed
+ /// block.
+ void removeNode(BasicBlock *BB) {
+ assert(getNode(BB) && "Removing node that isn't in dominator tree.");
+ Nodes.erase(BB);
+ }
+
+ /// print - Convert to human readable form
+ ///
+ virtual void print(std::ostream &OS, const Module* = 0) const;
+ void print(std::ostream *OS, const Module* M = 0) const {
+ if (OS) print(*OS, M);
+ }
+};
+
+//===-------------------------------------
+/// DominatorTree Class - Concrete subclass of DominatorTreeBase that is used to
+/// compute a normal dominator tree.
+///
+class DominatorTree : public DominatorTreeBase {
+public:
+ DominatorTree() : DominatorTreeBase(false) {}
+
+ BasicBlock *getRoot() const {
+ assert(Roots.size() == 1 && "Should always have entry node!");
+ return Roots[0];
+ }
+
+ virtual bool runOnFunction(Function &F);
+
+ virtual void getAnalysisUsage(AnalysisUsage &AU) const {
+ AU.setPreservesAll();
+ }
+private:
+ void calculate(Function& F);
+ Node *getNodeForBlock(BasicBlock *BB);
+ unsigned DFSPass(BasicBlock *V, InfoRec &VInfo, unsigned N);
+ void Compress(BasicBlock *V, InfoRec &VInfo);
+ BasicBlock *Eval(BasicBlock *v);
+ void Link(BasicBlock *V, BasicBlock *W, InfoRec &WInfo);
+ inline BasicBlock *getIDom(BasicBlock *BB) const {
+ std::map<BasicBlock*, BasicBlock*>::const_iterator I = IDoms.find(BB);
+ return I != IDoms.end() ? I->second : 0;
+ }
+};
+
+//===-------------------------------------
+/// DominatorTree GraphTraits specialization so the DominatorTree can be
+/// iterable by generic graph iterators.
+///
+template <> struct GraphTraits<DominatorTree::Node*> {
+ typedef DominatorTree::Node NodeType;
+ typedef NodeType::iterator ChildIteratorType;
+
+ static NodeType *getEntryNode(NodeType *N) {
+ return N;
+ }
+ static inline ChildIteratorType child_begin(NodeType* N) {
+ return N->begin();
+ }
+ static inline ChildIteratorType child_end(NodeType* N) {
+ return N->end();
+ }
+};
+
+template <> struct GraphTraits<DominatorTree*>
+ : public GraphTraits<DominatorTree::Node*> {
+ static NodeType *getEntryNode(DominatorTree *DT) {
+ return DT->getRootNode();
+ }
+};
+
+
+//===-------------------------------------
+/// ET-Forest Class - Class used to construct forwards and backwards
+/// ET-Forests
+///
+class ETForestBase : public DominatorBase {
+public:
+ ETForestBase(bool isPostDom) : DominatorBase(isPostDom), Nodes(),
+ DFSInfoValid(false), SlowQueries(0) {}
+
+ virtual void releaseMemory() { reset(); }
+
+ typedef std::map<BasicBlock*, ETNode*> ETMapType;
+
+ void updateDFSNumbers();
+
+ /// dominates - Return true if A dominates B.
+ ///
+ inline bool dominates(BasicBlock *A, BasicBlock *B) {
+ if (A == B)
+ return true;
+
+ ETNode *NodeA = getNode(A);
+ ETNode *NodeB = getNode(B);
+
+ if (DFSInfoValid)
+ return NodeB->DominatedBy(NodeA);
+ else {
+ // If we end up with too many slow queries, just update the
+ // DFS numbers on the theory that we are going to keep querying.
+ SlowQueries++;
+ if (SlowQueries > 32) {
+ updateDFSNumbers();
+ return NodeB->DominatedBy(NodeA);
+ }
+ return NodeB->DominatedBySlow(NodeA);
+ }
+ }
+
+ // dominates - Return true if A dominates B. This performs the
+ // special checks necessary if A and B are in the same basic block.
+ bool dominates(Instruction *A, Instruction *B);
+
+ /// properlyDominates - Return true if A dominates B and A != B.
+ ///
+ bool properlyDominates(BasicBlock *A, BasicBlock *B) {
+ return dominates(A, B) && A != B;
+ }
+
+ /// isReachableFromEntry - Return true if A is dominated by the entry
+ /// block of the function containing it.
+ const bool isReachableFromEntry(BasicBlock* A);
+
+ /// Return the nearest common dominator of A and B.
+ BasicBlock *nearestCommonDominator(BasicBlock *A, BasicBlock *B) const {
+ ETNode *NodeA = getNode(A);
+ ETNode *NodeB = getNode(B);
+
+ ETNode *Common = NodeA->NCA(NodeB);
+ if (!Common)
+ return NULL;
+ return Common->getData<BasicBlock>();
+ }
+
+ /// Return the immediate dominator of A.
+ BasicBlock *getIDom(BasicBlock *A) const {
+ ETNode *NodeA = getNode(A);
+ if (!NodeA) return 0;
+ const ETNode *idom = NodeA->getFather();
+ return idom ? idom->getData<BasicBlock>() : 0;
+ }
+
+ void getChildren(BasicBlock *A, std::vector<BasicBlock*>& children) const {
+ ETNode *NodeA = getNode(A);
+ if (!NodeA) return;
+ const ETNode* son = NodeA->getSon();
+
+ if (!son) return;
+ children.push_back(son->getData<BasicBlock>());
+
+ const ETNode* brother = son->getBrother();
+ while (brother != son) {
+ children.push_back(brother->getData<BasicBlock>());
+ brother = brother->getBrother();
+ }
+ }
+
+ virtual void getAnalysisUsage(AnalysisUsage &AU) const {
+ AU.setPreservesAll();
+ AU.addRequired<DominatorTree>();
+ }
+ //===--------------------------------------------------------------------===//
+ // API to update Forest information based on modifications
+ // to the CFG...
+
+ /// addNewBlock - Add a new block to the CFG, with the specified immediate
+ /// dominator.
+ ///
+ void addNewBlock(BasicBlock *BB, BasicBlock *IDom);
+
+ /// setImmediateDominator - Update the immediate dominator information to
+ /// change the current immediate dominator for the specified block
+ /// to another block. This method requires that BB for NewIDom
+ /// already have an ETNode, otherwise just use addNewBlock.
+ ///
+ void setImmediateDominator(BasicBlock *BB, BasicBlock *NewIDom);
+ /// print - Convert to human readable form
+ ///
+ virtual void print(std::ostream &OS, const Module* = 0) const;
+ void print(std::ostream *OS, const Module* M = 0) const {
+ if (OS) print(*OS, M);
+ }
+protected:
+ /// getNode - return the (Post)DominatorTree node for the specified basic
+ /// block. This is the same as using operator[] on this class.
+ ///
+ inline ETNode *getNode(BasicBlock *BB) const {
+ ETMapType::const_iterator i = Nodes.find(BB);
+ return (i != Nodes.end()) ? i->second : 0;
+ }
+
+ inline ETNode *operator[](BasicBlock *BB) const {
+ return getNode(BB);
+ }
+
+ void reset();
+ ETMapType Nodes;
+ bool DFSInfoValid;
+ unsigned int SlowQueries;
+
};
+//==-------------------------------------
+/// ETForest Class - Concrete subclass of ETForestBase that is used to
+/// compute a forwards ET-Forest.
+
+class ETForest : public ETForestBase {
+public:
+ ETForest() : ETForestBase(false) {}
+
+ BasicBlock *getRoot() const {
+ assert(Roots.size() == 1 && "Should always have entry node!");
+ return Roots[0];
+ }
+
+ virtual bool runOnFunction(Function &F) {
+ reset(); // Reset from the last time we were run...
+ DominatorTree &DT = getAnalysis<DominatorTree>();
+ Roots = DT.getRoots();
+ calculate(DT);
+ return false;
+ }
+
+ void calculate(const DominatorTree &DT);
+ ETNode *getNodeForBlock(BasicBlock *BB);
+};
//===----------------------------------------------------------------------===//
-//
-// DominanceFrontier - Calculate the dominance frontiers for a method.
-//
-class DominanceFrontier : public DominatorBase {
- typedef set<const BasicBlock*> DomSetType; // Dom set for a bb
- typedef map<const BasicBlock *, DomSetType> DomSetMapType; // Map of dom sets
-private:
+/// DominanceFrontierBase - Common base class for computing forward and inverse
+/// dominance frontiers for a function.
+///
+class DominanceFrontierBase : public DominatorBase {
+public:
+ typedef std::set<BasicBlock*> DomSetType; // Dom set for a bb
+ typedef std::map<BasicBlock*, DomSetType> DomSetMapType; // Dom set map
+protected:
DomSetMapType Frontiers;
- const DomSetType &calcDomFrontier(const DominatorTree &DT,
- const DominatorTree::Node *Node);
- const DomSetType &calcPostDomFrontier(const DominatorTree &DT,
- const DominatorTree::Node *Node);
public:
- DominanceFrontier(const DominatorSet &DS) : DominatorBase(DS.getRoot()) {
- const DominatorTree DT(DS);
- if (isPostDominator())
- calcPostDomFrontier(DT, DT[Root]);
- else
- calcDomFrontier(DT, DT[Root]);
- }
- DominanceFrontier(const ImmediateDominators &ID)
- : DominatorBase(ID.getRoot()) {
- const DominatorTree DT(ID);
- if (isPostDominator())
- calcPostDomFrontier(DT, DT[Root]);
- else
- calcDomFrontier(DT, DT[Root]);
- }
- DominanceFrontier(const DominatorTree &DT) : DominatorBase(DT.getRoot()) {
- if (isPostDominator())
- calcPostDomFrontier(DT, DT[Root]);
- else
- calcDomFrontier(DT, DT[Root]);
- }
+ DominanceFrontierBase(bool isPostDom) : DominatorBase(isPostDom) {}
+
+ virtual void releaseMemory() { Frontiers.clear(); }
// Accessor interface:
+ typedef DomSetMapType::iterator iterator;
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);}
+ iterator begin() { return Frontiers.begin(); }
+ const_iterator begin() const { return Frontiers.begin(); }
+ iterator end() { return Frontiers.end(); }
+ const_iterator end() const { return Frontiers.end(); }
+ iterator find(BasicBlock *B) { return Frontiers.find(B); }
+ const_iterator find(BasicBlock *B) const { return Frontiers.find(B); }
+
+ void addBasicBlock(BasicBlock *BB, const DomSetType &frontier) {
+ assert(find(BB) == end() && "Block already in DominanceFrontier!");
+ Frontiers.insert(std::make_pair(BB, frontier));
+ }
+
+ void addToFrontier(iterator I, BasicBlock *Node) {
+ assert(I != end() && "BB is not in DominanceFrontier!");
+ I->second.insert(Node);
+ }
+
+ void removeFromFrontier(iterator I, BasicBlock *Node) {
+ assert(I != end() && "BB is not in DominanceFrontier!");
+ assert(I->second.count(Node) && "Node is not in DominanceFrontier of BB");
+ I->second.erase(Node);
+ }
+
+ /// print - Convert to human readable form
+ ///
+ virtual void print(std::ostream &OS, const Module* = 0) const;
+ void print(std::ostream *OS, const Module* M = 0) const {
+ if (OS) print(*OS, M);
+ }
+};
+
+
+//===-------------------------------------
+/// DominanceFrontier Class - Concrete subclass of DominanceFrontierBase that is
+/// used to compute a forward dominator frontiers.
+///
+class DominanceFrontier : public DominanceFrontierBase {
+public:
+ DominanceFrontier() : DominanceFrontierBase(false) {}
+
+ BasicBlock *getRoot() const {
+ assert(Roots.size() == 1 && "Should always have entry node!");
+ return Roots[0];
+ }
+
+ virtual bool runOnFunction(Function &) {
+ Frontiers.clear();
+ DominatorTree &DT = getAnalysis<DominatorTree>();
+ Roots = DT.getRoots();
+ assert(Roots.size() == 1 && "Only one entry block for forward domfronts!");
+ calculate(DT, DT[Roots[0]]);
+ return false;
+ }
+
+ virtual void getAnalysisUsage(AnalysisUsage &AU) const {
+ AU.setPreservesAll();
+ AU.addRequired<DominatorTree>();
+ }
+private:
+ const DomSetType &calculate(const DominatorTree &DT,
+ const DominatorTree::Node *Node);
};
-} // End namespace cfg
+
+} // End llvm namespace
#endif
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