llvm-6502/include/llvm/Analysis/Dominators.h
2006-08-01 22:24:47 +00:00

671 lines
22 KiB
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. 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. ETForest: Efficient data structure for dominance comparisons and
// nearest-common-ancestor queries.
// 5. 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
// ImmediateDominator mapping.
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_ANALYSIS_DOMINATORS_H
#define LLVM_ANALYSIS_DOMINATORS_H
#include "llvm/Analysis/ET-Forest.h"
#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.
///
class DominatorBase : public FunctionPass {
protected:
std::vector<BasicBlock*> Roots;
const bool IsPostDominators;
inline DominatorBase(bool isPostDom) : Roots(), IsPostDominators(isPostDom) {}
public:
/// 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; }
};
//===----------------------------------------------------------------------===//
/// ImmediateDominators - Calculate the immediate dominator for each node in a
/// function.
///
class ImmediateDominatorsBase : public DominatorBase {
protected:
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){}
};
std::map<BasicBlock*, BasicBlock*> IDoms;
// 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;
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);
}
/// dominates - Return true if A dominates B.
///
bool dominates(BasicBlock *A, BasicBlock *B) const;
/// properlyDominates - Return true if A dominates B and A != B.
///
bool properlyDominates(BasicBlock *A, BasicBlock *B) const {
return A != B || properlyDominates(A, B);
}
/// 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 Module* = 0) const;
};
//===-------------------------------------
/// ImmediateDominators Class - Concrete subclass of ImmediateDominatorsBase
/// that is used to compute a normal immediate dominator set.
///
class ImmediateDominators : public ImmediateDominatorsBase {
public:
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:
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.
///
class DominatorSetBase : public DominatorBase {
public:
typedef std::set<BasicBlock*> DomSetType; // Dom set for a bb
// Map of dom sets
typedef std::map<BasicBlock*, DomSetType> DomSetMapType;
protected:
DomSetMapType Doms;
public:
DominatorSetBase(bool isPostDom) : DominatorBase(isPostDom) {}
virtual void releaseMemory() { Doms.clear(); }
// 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(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(BasicBlock *BB) const {
const_iterator I = find(BB);
assert(I != end() && "BB not in function!");
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 {
return getDominators(B).count(A) != 0;
}
/// properlyDominates - Return true if A dominates B and A != B.
///
bool properlyDominates(BasicBlock *A, BasicBlock *B) const {
return dominates(A, B) && A != B;
}
/// print - Convert to human readable form
///
virtual void print(std::ostream &OS, const Module* = 0) const;
/// 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) const;
//===--------------------------------------------------------------------===//
// API to update (Post)DominatorSet information based on modifications to
// the CFG...
/// 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.
///
void addDominator(BasicBlock *BB, BasicBlock *NewDominator) {
iterator I = find(BB);
assert(I != end() && "BB is not in DominatorSet!");
I->second.insert(NewDominator);
}
};
//===-------------------------------------
/// DominatorSet Class - Concrete subclass of DominatorSetBase that is used to
/// compute a normal dominator set.
///
class DominatorSet : public DominatorSetBase {
public:
DominatorSet() : DominatorSetBase(false) {}
virtual bool runOnFunction(Function &F);
BasicBlock *getRoot() const {
assert(Roots.size() == 1 && "Should always have entry node!");
return Roots[0];
}
/// getAnalysisUsage - This simply provides a dominator set
///
virtual void getAnalysisUsage(AnalysisUsage &AU) const {
AU.addRequired<ImmediateDominators>();
AU.setPreservesAll();
}
// stub - dummy function, just ignore it
static int stub;
};
//===----------------------------------------------------------------------===//
/// DominatorTree - Calculate the immediate dominator tree for a function.
///
class DominatorTreeBase : public DominatorBase {
public:
class Node;
protected:
std::map<BasicBlock*, Node*> Nodes;
void reset();
typedef std::map<BasicBlock*, Node*> NodeMapType;
Node *RootNode;
public:
class Node {
friend struct DominatorTree;
friend struct PostDominatorTree;
friend struct DominatorTreeBase;
BasicBlock *TheBB;
Node *IDom;
std::vector<Node*> Children;
public:
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; }
/// 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
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(BasicBlock *BB, Node *iDom) : TheBB(BB), IDom(iDom) {}
inline Node *addChild(Node *C) { Children.push_back(C); return C; }
void setIDom(Node *NewIDom);
};
public:
DominatorTreeBase(bool isPostDom) : DominatorBase(isPostDom) {}
~DominatorTreeBase() { reset(); }
virtual void releaseMemory() { reset(); }
/// 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);
}
/// print - Convert to human readable form
///
virtual void print(std::ostream &OS, const Module* = 0) const;
};
//===-------------------------------------
/// 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);
}
}
/// properlyDominates - Return true if A dominates B and A != B.
///
bool properlyDominates(BasicBlock *A, BasicBlock *B) {
return dominates(A, B) && A != B;
}
/// 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>();
}
virtual void getAnalysisUsage(AnalysisUsage &AU) const {
AU.setPreservesAll();
AU.addRequired<ImmediateDominators>();
}
//===--------------------------------------------------------------------===//
// 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;
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...
ImmediateDominators &ID = getAnalysis<ImmediateDominators>();
Roots = ID.getRoots();
calculate(ID);
return false;
}
void calculate(const ImmediateDominators &ID);
ETNode *getNodeForBlock(BasicBlock *BB);
};
//===-------------------------------------
/// 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) {
reset(); // Reset from the last time we were run...
ImmediateDominators &ID = getAnalysis<ImmediateDominators>();
Roots = ID.getRoots();
calculate(ID);
return false;
}
virtual void getAnalysisUsage(AnalysisUsage &AU) const {
AU.setPreservesAll();
AU.addRequired<ImmediateDominators>();
}
private:
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();
}
};
//===----------------------------------------------------------------------===//
/// 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;
public:
DominanceFrontierBase(bool isPostDom) : DominatorBase(isPostDom) {}
virtual void releaseMemory() { Frontiers.clear(); }
// Accessor interface:
typedef DomSetMapType::iterator iterator;
typedef DomSetMapType::const_iterator const_iterator;
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;
};
//===-------------------------------------
/// 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 llvm namespace
// Make sure that any clients of this file link in Dominators.cpp
FORCE_DEFINING_FILE_TO_BE_LINKED(DominatorSet)
#endif