-//===- llvm/Analysis/Dominators.h - Dominator Info 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 function
-// 2. ImmediateDominators: Calculates and holds a mapping between BasicBlocks
+// 1. ImmediateDominators: Calculates and holds a mapping between BasicBlocks
// and their immediate dominator.
+// 2. DominatorSet: Calculates the [reverse] dominator set for a function
// 3. DominatorTree: Represent the ImmediateDominator as an explicit tree
// structure.
// 4. DominanceFrontier: Calculate and hold the dominance frontier for a
#include "llvm/Pass.h"
#include <set>
+
+namespace llvm {
+
class Instruction;
+template <typename GraphType> struct GraphTraits;
+
//===----------------------------------------------------------------------===//
-//
-// DominatorBase - Base class that other, more interesting dominator analyses
-// inherit from.
-//
+/// DominatorBase - Base class that other, more interesting dominator analyses
+/// inherit from.
+///
class DominatorBase : public FunctionPass {
protected:
- BasicBlock *Root;
+ std::vector<BasicBlock*> Roots;
const bool IsPostDominators;
- inline DominatorBase(bool isPostDom) : Root(0), IsPostDominators(isPostDom) {}
+ inline DominatorBase(bool isPostDom) : Roots(), IsPostDominators(isPostDom) {}
public:
- inline BasicBlock *getRoot() const { return Root; }
+ /// 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; }
- // Returns true if analysis based of postdoms
+ /// isPostDominator - Returns true if analysis based of postdoms
+ ///
bool isPostDominator() const { return IsPostDominators; }
};
+
//===----------------------------------------------------------------------===//
-//
-// DominatorSet - Maintain a set<BasicBlock*> for every basic block in a
-// function, that represents the blocks that dominate the block.
-//
-class DominatorSetBase : public DominatorBase {
+/// ImmediateDominators - Calculate the immediate dominator for each node in a
+/// function.
+///
+class ImmediateDominatorsBase : public DominatorBase {
+protected:
+ std::map<BasicBlock*, BasicBlock*> IDoms;
public:
+ ImmediateDominatorsBase(bool isPostDom) : DominatorBase(isPostDom) {}
+
+ virtual void releaseMemory() { IDoms.clear(); }
+
+ // Accessor interface:
+ typedef std::map<BasicBlock*, 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(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 BasicBlock *operator[](BasicBlock *BB) const {
+ return get(BB);
+ }
+
+ /// get() - Synonym for operator[].
+ ///
+ inline BasicBlock *get(BasicBlock *BB) const {
+ std::map<BasicBlock*, BasicBlock*>::const_iterator I = IDoms.find(BB);
+ return I != IDoms.end() ? I->second : 0;
+ }
+
+ //===--------------------------------------------------------------------===//
+ // API to update Immediate(Post)Dominators 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) {
+ assert(get(BB) == 0 && "BasicBlock already in idom info!");
+ IDoms[BB] = 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 already have an IDom, otherwise just
+ /// use addNewBlock.
+ ///
+ void setImmediateDominator(BasicBlock *BB, BasicBlock *NewIDom) {
+ assert(IDoms.find(BB) != IDoms.end() && "BB doesn't have idom yet!");
+ IDoms[BB] = NewIDom;
+ }
+
+ /// print - Convert to human readable form
+ ///
+ virtual void print(std::ostream &OS) const;
+};
+
+//===-------------------------------------
+/// ImmediateDominators Class - Concrete subclass of ImmediateDominatorsBase
+/// that is used to compute a normal immediate dominator set.
+///
+struct ImmediateDominators : public ImmediateDominatorsBase {
+ ImmediateDominators() : ImmediateDominatorsBase(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:
+ struct InfoRec {
+ unsigned Semi;
+ unsigned Size;
+ BasicBlock *Label, *Parent, *Child, *Ancestor;
+
+ std::vector<BasicBlock*> Bucket;
+
+ InfoRec() : Semi(0), Size(0), Label(0), Parent(0), Child(0), Ancestor(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;
+
+ 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);
+};
+
+
+
+//===----------------------------------------------------------------------===//
+/// DominatorSet - Maintain a set<BasicBlock*> for every basic block in a
+/// function, that represents the blocks that dominate the block. If the block
+/// is unreachable in this function, the set will be empty. This cannot happen
+/// for reachable code, because every block dominates at least itself.
+///
+struct DominatorSetBase : public DominatorBase {
typedef std::set<BasicBlock*> DomSetType; // Dom set for a bb
// Map of dom sets
typedef std::map<BasicBlock*, DomSetType> DomSetMapType;
return I->second;
}
+ /// isReachable - Return true if the specified basicblock is reachable. If
+ /// the block is reachable, we have dominator set information for it.
+ ///
+ bool isReachable(BasicBlock *BB) const {
+ return !getDominators(BB).empty();
+ }
+
/// dominates - Return true if A dominates B.
///
inline bool dominates(BasicBlock *A, BasicBlock *B) const {
}
/// print - Convert to human readable form
+ ///
virtual void print(std::ostream &OS) const;
/// dominates - Return true if A dominates B. This performs the special
- /// checks neccesary if A and B are in the same basic block.
+ /// checks necessary if A and B are in the same basic block.
///
bool dominates(Instruction *A, Instruction *B) const;
/// addBasicBlock - Call to update the dominator set with information about a
/// new block that was inserted into the function.
+ ///
void addBasicBlock(BasicBlock *BB, const DomSetType &Dominators) {
assert(find(BB) == end() && "Block already in DominatorSet!");
Doms.insert(std::make_pair(BB, Dominators));
}
- // addDominator - If a new block is inserted into the CFG, then method may be
- // called to notify the blocks it dominates that it is in their set.
- //
+ /// addDominator - If a new block is inserted into the CFG, then method may be
+ /// called to notify the blocks it dominates that it is in their set.
+ ///
void addDominator(BasicBlock *BB, BasicBlock *NewDominator) {
iterator I = find(BB);
assert(I != end() && "BB is not in DominatorSet!");
//===-------------------------------------
-// DominatorSet Class - Concrete subclass of DominatorSetBase that is used to
-// compute a normal dominator set.
-//
+/// DominatorSet Class - Concrete subclass of DominatorSetBase that is used to
+/// compute a normal dominator set.
+///
struct DominatorSet : public DominatorSetBase {
DominatorSet() : DominatorSetBase(false) {}
virtual bool runOnFunction(Function &F);
- // getAnalysisUsage - This simply provides a dominator set
- virtual void getAnalysisUsage(AnalysisUsage &AU) const {
- AU.setPreservesAll();
+ BasicBlock *getRoot() const {
+ assert(Roots.size() == 1 && "Should always have entry node!");
+ return Roots[0];
}
-private:
- void calculateDominatorsFromBlock(BasicBlock *BB);
-};
-
-//===----------------------------------------------------------------------===//
-//
-// ImmediateDominators - Calculate the immediate dominator for each node in a
-// function.
-//
-class ImmediateDominatorsBase : public DominatorBase {
-protected:
- std::map<BasicBlock*, BasicBlock*> IDoms;
- void calcIDoms(const DominatorSetBase &DS);
-public:
- ImmediateDominatorsBase(bool isPostDom) : DominatorBase(isPostDom) {}
-
- virtual void releaseMemory() { IDoms.clear(); }
-
- // Accessor interface:
- typedef std::map<BasicBlock*, 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(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 BasicBlock *operator[](BasicBlock *BB) const {
- return get(BB);
- }
-
- // get() - Synonym for operator[].
- inline BasicBlock *get(BasicBlock *BB) const {
- std::map<BasicBlock*, BasicBlock*>::const_iterator I = IDoms.find(BB);
- return I != IDoms.end() ? I->second : 0;
- }
-
- //===--------------------------------------------------------------------===//
- // API to update Immediate(Post)Dominators information based on modifications
- // to the CFG...
-
- /// addNewBlock - Add a new block to the CFG, with the specified immediate
- /// dominator.
+ /// getAnalysisUsage - This simply provides a dominator set
///
- void addNewBlock(BasicBlock *BB, BasicBlock *IDom) {
- assert(get(BB) == 0 && "BasicBlock already in idom info!");
- IDoms[BB] = IDom;
- }
-
-
- // print - Convert to human readable form
- virtual void print(std::ostream &OS) const;
-};
-
-//===-------------------------------------
-// ImmediateDominators Class - Concrete subclass of ImmediateDominatorsBase that
-// is used to compute a normal immediate dominator set.
-//
-struct ImmediateDominators : public ImmediateDominatorsBase {
- ImmediateDominators() : ImmediateDominatorsBase(false) {}
-
- virtual bool runOnFunction(Function &F) {
- IDoms.clear(); // Reset from the last time we were run...
- DominatorSet &DS = getAnalysis<DominatorSet>();
- Root = DS.getRoot();
- calcIDoms(DS);
- return false;
- }
-
virtual void getAnalysisUsage(AnalysisUsage &AU) const {
+ AU.addRequired<ImmediateDominators>();
AU.setPreservesAll();
- AU.addRequired<DominatorSet>();
}
};
//===----------------------------------------------------------------------===//
-//
-// DominatorTree - Calculate the immediate dominator tree for a function.
-//
-class DominatorTreeBase : public DominatorBase {
-protected:
- class Node2;
-public:
- typedef Node2 Node;
+/// DominatorTree - Calculate the immediate dominator tree for a function.
+///
+struct DominatorTreeBase : public DominatorBase {
+ class Node;
protected:
std::map<BasicBlock*, Node*> Nodes;
void reset();
typedef std::map<BasicBlock*, Node*> NodeMapType;
+
+ Node *RootNode;
public:
- class Node2 : public std::vector<Node*> {
+ class Node {
friend class DominatorTree;
friend class PostDominatorTree;
friend class DominatorTreeBase;
- BasicBlock *TheNode;
- Node2 *IDom;
+ BasicBlock *TheBB;
+ Node *IDom;
+ std::vector<Node*> Children;
public:
- inline BasicBlock *getNode() const { return TheNode; }
- inline Node2 *getIDom() const { return IDom; }
- inline const std::vector<Node*> &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;
+ 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 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 {
+ const Node *IDom;
while ((IDom = N->getIDom()) != 0 && IDom != this)
- N = IDom; // Walk up the tree
+ N = IDom; // Walk up the tree
return IDom != 0;
}
private:
- inline Node2(BasicBlock *node, Node *iDom)
- : TheNode(node), IDom(iDom) {}
- inline Node2 *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:
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...
///
Node *createNewNode(BasicBlock *BB, Node *IDomNode) {
assert(getNode(BB) == 0 && "Block already in dominator tree!");
- Node *New = Nodes[BB] = new Node(BB, IDomNode);
- if (IDomNode) IDomNode->addChild(New);
- return New;
+ 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 *Node, Node *NewIDom) {
+ assert(Node && NewIDom && "Cannot change null node pointers!");
+ Node->setIDom(NewIDom);
}
/// print - Convert to human readable form
+ ///
virtual void print(std::ostream &OS) const;
};
//===-------------------------------------
-// DominatorTree Class - Concrete subclass of DominatorTreeBase that is used to
-// compute a normal dominator tree.
-//
+/// DominatorTree Class - Concrete subclass of DominatorTreeBase that is used to
+/// compute a normal dominator tree.
+///
struct DominatorTree : public DominatorTreeBase {
DominatorTree() : DominatorTreeBase(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...
- DominatorSet &DS = getAnalysis<DominatorSet>();
- Root = DS.getRoot();
- calculate(DS);
+ ImmediateDominators &ID = getAnalysis<ImmediateDominators>();
+ Roots = ID.getRoots();
+ calculate(ID);
return false;
}
virtual void getAnalysisUsage(AnalysisUsage &AU) const {
AU.setPreservesAll();
- AU.addRequired<DominatorSet>();
+ AU.addRequired<ImmediateDominators>();
}
private:
- void calculate(const DominatorSet &DS);
+ void calculate(const ImmediateDominators &ID);
+ Node *getNodeForBlock(BasicBlock *BB);
};
+//===-------------------------------------
+/// 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();
+ }
+};
//===----------------------------------------------------------------------===//
-//
-// DominanceFrontier - Calculate the dominance frontiers for a function.
-//
-class DominanceFrontierBase : public DominatorBase {
-public:
+/// DominanceFrontier - Calculate the dominance frontiers for a function.
+///
+struct DominanceFrontierBase : public DominatorBase {
typedef std::set<BasicBlock*> DomSetType; // Dom set for a bb
typedef std::map<BasicBlock*, DomSetType> DomSetMapType; // Dom set map
protected:
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(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);
+ }
- // print - Convert to human readable form
+ 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;
};
//===-------------------------------------
-// DominatorTree Class - Concrete subclass of DominatorTreeBase that is used to
-// compute a normal dominator tree.
-//
+/// DominatorTree Class - Concrete subclass of DominatorTreeBase that is used to
+/// compute a normal dominator tree.
+///
struct DominanceFrontier : public DominanceFrontierBase {
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>();
- Root = DT.getRoot();
- calculate(DT, DT[Root]);
+ Roots = DT.getRoots();
+ assert(Roots.size() == 1 && "Only one entry block for forward domfronts!");
+ calculate(DT, DT[Roots[0]]);
return false;
}
const DominatorTree::Node *Node);
};
+} // End llvm namespace
+
#endif