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llvm-6502/include/llvm/Analysis/Dominators.h
Dan Gohman 3445d9a72a Add const qualifiers to dominates' arguments. 
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@80801 91177308-0d34-0410-b5e6-96231b3b80d8
2009-09-02 17:05:05 +00:00

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//===- llvm/Analysis/Dominators.h - Dominator Info Calculation --*- C++ -*-===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file defines the following classes:
// 1. DominatorTree: Represent dominators as an explicit tree structure.
// 2. 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
// DominatorTree mapping.
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_ANALYSIS_DOMINATORS_H
#define LLVM_ANALYSIS_DOMINATORS_H
#include "llvm/Pass.h"
#include "llvm/Function.h"
#include "llvm/Instructions.h"
#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/GraphTraits.h"
#include "llvm/ADT/SmallPtrSet.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/Assembly/Writer.h"
#include "llvm/Support/CFG.h"
#include "llvm/Support/Compiler.h"
#include "llvm/Support/raw_ostream.h"
#include <algorithm>
#include <map>
#include <set>
namespace llvm {
//===----------------------------------------------------------------------===//
/// DominatorBase - Base class that other, more interesting dominator analyses
/// inherit from.
///
template <class NodeT>
class DominatorBase {
protected:
std::vector<NodeT*> Roots;
const bool IsPostDominators;
inline explicit 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<NodeT*> &getRoots() const { return Roots; }
/// isPostDominator - Returns true if analysis based of postdoms
///
bool isPostDominator() const { return IsPostDominators; }
};
//===----------------------------------------------------------------------===//
// DomTreeNode - Dominator Tree Node
template<class NodeT> class DominatorTreeBase;
struct PostDominatorTree;
class MachineBasicBlock;
template <class NodeT>
class DomTreeNodeBase {
NodeT *TheBB;
DomTreeNodeBase<NodeT> *IDom;
std::vector<DomTreeNodeBase<NodeT> *> Children;
int DFSNumIn, DFSNumOut;
template<class N> friend class DominatorTreeBase;
friend struct PostDominatorTree;
public:
typedef typename std::vector<DomTreeNodeBase<NodeT> *>::iterator iterator;
typedef typename std::vector<DomTreeNodeBase<NodeT> *>::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(); }
NodeT *getBlock() const { return TheBB; }
DomTreeNodeBase<NodeT> *getIDom() const { return IDom; }
const std::vector<DomTreeNodeBase<NodeT>*> &getChildren() const {
return Children;
}
DomTreeNodeBase(NodeT *BB, DomTreeNodeBase<NodeT> *iDom)
: TheBB(BB), IDom(iDom), DFSNumIn(-1), DFSNumOut(-1) { }
DomTreeNodeBase<NodeT> *addChild(DomTreeNodeBase<NodeT> *C) {
Children.push_back(C);
return C;
}
size_t getNumChildren() const {
return Children.size();
}
void clearAllChildren() {
Children.clear();
}
bool compare(DomTreeNodeBase<NodeT> *Other) {
if (getNumChildren() != Other->getNumChildren())
return true;
SmallPtrSet<NodeT *, 4> OtherChildren;
for(iterator I = Other->begin(), E = Other->end(); I != E; ++I) {
NodeT *Nd = (*I)->getBlock();
OtherChildren.insert(Nd);
}
for(iterator I = begin(), E = end(); I != E; ++I) {
NodeT *N = (*I)->getBlock();
if (OtherChildren.count(N) == 0)
return true;
}
return false;
}
void setIDom(DomTreeNodeBase<NodeT> *NewIDom) {
assert(IDom && "No immediate dominator?");
if (IDom != NewIDom) {
typename std::vector<DomTreeNodeBase<NodeT>*>::iterator I =
std::find(IDom->Children.begin(), IDom->Children.end(), this);
assert(I != IDom->Children.end() &&
"Not in immediate dominator children set!");
// I am no longer your child...
IDom->Children.erase(I);
// Switch to new dominator
IDom = NewIDom;
IDom->Children.push_back(this);
}
}
/// getDFSNumIn/getDFSNumOut - These are an internal implementation detail, do
/// not call them.
unsigned getDFSNumIn() const { return DFSNumIn; }
unsigned getDFSNumOut() const { return DFSNumOut; }
private:
// Return true if this node is dominated by other. Use this only if DFS info
// is valid.
bool DominatedBy(const DomTreeNodeBase<NodeT> *other) const {
return this->DFSNumIn >= other->DFSNumIn &&
this->DFSNumOut <= other->DFSNumOut;
}
};
EXTERN_TEMPLATE_INSTANTIATION(class DomTreeNodeBase<BasicBlock>);
EXTERN_TEMPLATE_INSTANTIATION(class DomTreeNodeBase<MachineBasicBlock>);
template<class NodeT>
static raw_ostream &operator<<(raw_ostream &o,
const DomTreeNodeBase<NodeT> *Node) {
if (Node->getBlock())
WriteAsOperand(o, Node->getBlock(), false);
else
o << " <<exit node>>";
o << " {" << Node->getDFSNumIn() << "," << Node->getDFSNumOut() << "}";
return o << "\n";
}
template<class NodeT>
static void PrintDomTree(const DomTreeNodeBase<NodeT> *N, raw_ostream &o,
unsigned Lev) {
o.indent(2*Lev) << "[" << Lev << "] " << N;
for (typename DomTreeNodeBase<NodeT>::const_iterator I = N->begin(),
E = N->end(); I != E; ++I)
PrintDomTree<NodeT>(*I, o, Lev+1);
}
typedef DomTreeNodeBase<BasicBlock> DomTreeNode;
//===----------------------------------------------------------------------===//
/// DominatorTree - Calculate the immediate dominator tree for a function.
///
template<class FuncT, class N>
void Calculate(DominatorTreeBase<typename GraphTraits<N>::NodeType>& DT,
FuncT& F);
template<class NodeT>
class DominatorTreeBase : public DominatorBase<NodeT> {
protected:
typedef DenseMap<NodeT*, DomTreeNodeBase<NodeT>*> DomTreeNodeMapType;
DomTreeNodeMapType DomTreeNodes;
DomTreeNodeBase<NodeT> *RootNode;
bool DFSInfoValid;
unsigned int SlowQueries;
// Information record used during immediate dominators computation.
struct InfoRec {
unsigned DFSNum;
unsigned Semi;
unsigned Size;
NodeT *Label, *Child;
unsigned Parent, Ancestor;
std::vector<NodeT*> Bucket;
InfoRec() : DFSNum(0), Semi(0), Size(0), Label(0), Child(0), Parent(0),
Ancestor(0) {}
};
DenseMap<NodeT*, NodeT*> IDoms;
// Vertex - Map the DFS number to the BasicBlock*
std::vector<NodeT*> Vertex;
// Info - Collection of information used during the computation of idoms.
DenseMap<NodeT*, InfoRec> Info;
void reset() {
for (typename DomTreeNodeMapType::iterator I = this->DomTreeNodes.begin(),
E = DomTreeNodes.end(); I != E; ++I)
delete I->second;
DomTreeNodes.clear();
IDoms.clear();
this->Roots.clear();
Vertex.clear();
RootNode = 0;
}
// NewBB is split and now it has one successor. Update dominator tree to
// reflect this change.
template<class N, class GraphT>
void Split(DominatorTreeBase<typename GraphT::NodeType>& DT,
typename GraphT::NodeType* NewBB) {
assert(std::distance(GraphT::child_begin(NewBB), GraphT::child_end(NewBB)) == 1
&& "NewBB should have a single successor!");
typename GraphT::NodeType* NewBBSucc = *GraphT::child_begin(NewBB);
std::vector<typename GraphT::NodeType*> PredBlocks;
for (typename GraphTraits<Inverse<N> >::ChildIteratorType PI =
GraphTraits<Inverse<N> >::child_begin(NewBB),
PE = GraphTraits<Inverse<N> >::child_end(NewBB); PI != PE; ++PI)
PredBlocks.push_back(*PI);
assert(!PredBlocks.empty() && "No predblocks??");
bool NewBBDominatesNewBBSucc = true;
for (typename GraphTraits<Inverse<N> >::ChildIteratorType PI =
GraphTraits<Inverse<N> >::child_begin(NewBBSucc),
E = GraphTraits<Inverse<N> >::child_end(NewBBSucc); PI != E; ++PI)
if (*PI != NewBB && !DT.dominates(NewBBSucc, *PI) &&
DT.isReachableFromEntry(*PI)) {
NewBBDominatesNewBBSucc = false;
break;
}
// Find NewBB's immediate dominator and create new dominator tree node for
// NewBB.
NodeT *NewBBIDom = 0;
unsigned i = 0;
for (i = 0; i < PredBlocks.size(); ++i)
if (DT.isReachableFromEntry(PredBlocks[i])) {
NewBBIDom = PredBlocks[i];
break;
}
// It's possible that none of the predecessors of NewBB are reachable;
// in that case, NewBB itself is unreachable, so nothing needs to be
// changed.
if (!NewBBIDom)
return;
for (i = i + 1; i < PredBlocks.size(); ++i) {
if (DT.isReachableFromEntry(PredBlocks[i]))
NewBBIDom = DT.findNearestCommonDominator(NewBBIDom, PredBlocks[i]);
}
// Create the new dominator tree node... and set the idom of NewBB.
DomTreeNodeBase<NodeT> *NewBBNode = DT.addNewBlock(NewBB, NewBBIDom);
// If NewBB strictly dominates other blocks, then it is now the immediate
// dominator of NewBBSucc. Update the dominator tree as appropriate.
if (NewBBDominatesNewBBSucc) {
DomTreeNodeBase<NodeT> *NewBBSuccNode = DT.getNode(NewBBSucc);
DT.changeImmediateDominator(NewBBSuccNode, NewBBNode);
}
}
public:
explicit DominatorTreeBase(bool isPostDom)
: DominatorBase<NodeT>(isPostDom), DFSInfoValid(false), SlowQueries(0) {}
virtual ~DominatorTreeBase() { reset(); }
// FIXME: Should remove this
virtual bool runOnFunction(Function &F) { return false; }
/// compare - Return false if the other dominator tree base matches this
/// dominator tree base. Otherwise return true.
bool compare(DominatorTreeBase &Other) const {
const DomTreeNodeMapType &OtherDomTreeNodes = Other.DomTreeNodes;
if (DomTreeNodes.size() != OtherDomTreeNodes.size())
return true;
SmallPtrSet<const NodeT *,4> MyBBs;
for (typename DomTreeNodeMapType::const_iterator
I = this->DomTreeNodes.begin(),
E = this->DomTreeNodes.end(); I != E; ++I) {
NodeT *BB = I->first;
typename DomTreeNodeMapType::const_iterator OI = OtherDomTreeNodes.find(BB);
if (OI == OtherDomTreeNodes.end())
return true;
DomTreeNodeBase<NodeT>* MyNd = I->second;
DomTreeNodeBase<NodeT>* OtherNd = OI->second;
if (MyNd->compare(OtherNd))
return true;
}
return false;
}
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 DomTreeNodeBase<NodeT> *getNode(NodeT *BB) const {
typename DomTreeNodeMapType::const_iterator I = DomTreeNodes.find(BB);
return I != DomTreeNodes.end() ? I->second : 0;
}
/// 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.
///
DomTreeNodeBase<NodeT> *getRootNode() { return RootNode; }
const DomTreeNodeBase<NodeT> *getRootNode() const { return RootNode; }
/// properlyDominates - Returns true iff this dominates N and this != N.
/// Note that this is not a constant time operation!
///
bool properlyDominates(const DomTreeNodeBase<NodeT> *A,
const DomTreeNodeBase<NodeT> *B) const {
if (A == 0 || B == 0) return false;
return dominatedBySlowTreeWalk(A, B);
}
inline bool properlyDominates(NodeT *A, NodeT *B) {
return properlyDominates(getNode(A), getNode(B));
}
bool dominatedBySlowTreeWalk(const DomTreeNodeBase<NodeT> *A,
const DomTreeNodeBase<NodeT> *B) const {
const DomTreeNodeBase<NodeT> *IDom;
if (A == 0 || B == 0) return false;
while ((IDom = B->getIDom()) != 0 && IDom != A && IDom != B)
B = IDom; // Walk up the tree
return IDom != 0;
}
/// isReachableFromEntry - Return true if A is dominated by the entry
/// block of the function containing it.
bool isReachableFromEntry(NodeT* A) {
assert (!this->isPostDominator()
&& "This is not implemented for post dominators");
return dominates(&A->getParent()->front(), A);
}
/// dominates - Returns true iff A dominates B. Note that this is not a
/// constant time operation!
///
inline bool dominates(const DomTreeNodeBase<NodeT> *A,
const DomTreeNodeBase<NodeT> *B) {
if (B == A)
return true; // A node trivially dominates itself.
if (A == 0 || B == 0)
return false;
if (DFSInfoValid)
return B->DominatedBy(A);
// 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 B->DominatedBy(A);
}
return dominatedBySlowTreeWalk(A, B);
}
inline bool dominates(const NodeT *A, const NodeT *B) {
if (A == B)
return true;
// Cast away the const qualifiers here. This is ok since
// this function doesn't actually return the values returned
// from getNode.
return dominates(getNode(const_cast<NodeT *>(A)),
getNode(const_cast<NodeT *>(B)));
}
NodeT *getRoot() const {
assert(this->Roots.size() == 1 && "Should always have entry node!");
return this->Roots[0];
}
/// findNearestCommonDominator - Find nearest common dominator basic block
/// for basic block A and B. If there is no such block then return NULL.
NodeT *findNearestCommonDominator(NodeT *A, NodeT *B) {
assert (!this->isPostDominator()
&& "This is not implemented for post dominators");
assert (A->getParent() == B->getParent()
&& "Two blocks are not in same function");
// If either A or B is a entry block then it is nearest common dominator.
NodeT &Entry = A->getParent()->front();
if (A == &Entry || B == &Entry)
return &Entry;
// If B dominates A then B is nearest common dominator.
if (dominates(B, A))
return B;
// If A dominates B then A is nearest common dominator.
if (dominates(A, B))
return A;
DomTreeNodeBase<NodeT> *NodeA = getNode(A);
DomTreeNodeBase<NodeT> *NodeB = getNode(B);
// Collect NodeA dominators set.
SmallPtrSet<DomTreeNodeBase<NodeT>*, 16> NodeADoms;
NodeADoms.insert(NodeA);
DomTreeNodeBase<NodeT> *IDomA = NodeA->getIDom();
while (IDomA) {
NodeADoms.insert(IDomA);
IDomA = IDomA->getIDom();
}
// Walk NodeB immediate dominators chain and find common dominator node.
DomTreeNodeBase<NodeT> *IDomB = NodeB->getIDom();
while(IDomB) {
if (NodeADoms.count(IDomB) != 0)
return IDomB->getBlock();
IDomB = IDomB->getIDom();
}
return NULL;
}
//===--------------------------------------------------------------------===//
// API to update (Post)DominatorTree information based on modifications to
// the CFG...
/// addNewBlock - Add a new node to the dominator tree information. This
/// creates a new node as a child of DomBB dominator node,linking it into
/// the children list of the immediate dominator.
DomTreeNodeBase<NodeT> *addNewBlock(NodeT *BB, NodeT *DomBB) {
assert(getNode(BB) == 0 && "Block already in dominator tree!");
DomTreeNodeBase<NodeT> *IDomNode = getNode(DomBB);
assert(IDomNode && "Not immediate dominator specified for block!");
DFSInfoValid = false;
return DomTreeNodes[BB] =
IDomNode->addChild(new DomTreeNodeBase<NodeT>(BB, IDomNode));
}
/// changeImmediateDominator - This method is used to update the dominator
/// tree information when a node's immediate dominator changes.
///
void changeImmediateDominator(DomTreeNodeBase<NodeT> *N,
DomTreeNodeBase<NodeT> *NewIDom) {
assert(N && NewIDom && "Cannot change null node pointers!");
DFSInfoValid = false;
N->setIDom(NewIDom);
}
void changeImmediateDominator(NodeT *BB, NodeT *NewBB) {
changeImmediateDominator(getNode(BB), getNode(NewBB));
}
/// eraseNode - Removes a node from the dominator tree. Block must not
/// domiante any other blocks. Removes node from its immediate dominator's
/// children list. Deletes dominator node associated with basic block BB.
void eraseNode(NodeT *BB) {
DomTreeNodeBase<NodeT> *Node = getNode(BB);
assert (Node && "Removing node that isn't in dominator tree.");
assert (Node->getChildren().empty() && "Node is not a leaf node.");
// Remove node from immediate dominator's children list.
DomTreeNodeBase<NodeT> *IDom = Node->getIDom();
if (IDom) {
typename std::vector<DomTreeNodeBase<NodeT>*>::iterator I =
std::find(IDom->Children.begin(), IDom->Children.end(), Node);
assert(I != IDom->Children.end() &&
"Not in immediate dominator children set!");
// I am no longer your child...
IDom->Children.erase(I);
}
DomTreeNodes.erase(BB);
delete Node;
}
/// removeNode - Removes a node from the dominator tree. Block must not
/// dominate any other blocks. Invalidates any node pointing to removed
/// block.
void removeNode(NodeT *BB) {
assert(getNode(BB) && "Removing node that isn't in dominator tree.");
DomTreeNodes.erase(BB);
}
/// splitBlock - BB is split and now it has one successor. Update dominator
/// tree to reflect this change.
void splitBlock(NodeT* NewBB) {
if (this->IsPostDominators)
this->Split<Inverse<NodeT*>, GraphTraits<Inverse<NodeT*> > >(*this, NewBB);
else
this->Split<NodeT*, GraphTraits<NodeT*> >(*this, NewBB);
}
/// print - Convert to human readable form
///
void print(raw_ostream &o) const {
o << "=============================--------------------------------\n";
if (this->isPostDominator())
o << "Inorder PostDominator Tree: ";
else
o << "Inorder Dominator Tree: ";
if (this->DFSInfoValid)
o << "DFSNumbers invalid: " << SlowQueries << " slow queries.";
o << "\n";
PrintDomTree<NodeT>(getRootNode(), o, 1);
}
protected:
template<class GraphT>
friend void Compress(DominatorTreeBase<typename GraphT::NodeType>& DT,
typename GraphT::NodeType* VIn);
template<class GraphT>
friend typename GraphT::NodeType* Eval(
DominatorTreeBase<typename GraphT::NodeType>& DT,
typename GraphT::NodeType* V);
template<class GraphT>
friend void Link(DominatorTreeBase<typename GraphT::NodeType>& DT,
unsigned DFSNumV, typename GraphT::NodeType* W,
typename DominatorTreeBase<typename GraphT::NodeType>::InfoRec &WInfo);
template<class GraphT>
friend unsigned DFSPass(DominatorTreeBase<typename GraphT::NodeType>& DT,
typename GraphT::NodeType* V,
unsigned N);
template<class FuncT, class N>
friend void Calculate(DominatorTreeBase<typename GraphTraits<N>::NodeType>& DT,
FuncT& F);
/// updateDFSNumbers - Assign In and Out numbers to the nodes while walking
/// dominator tree in dfs order.
void updateDFSNumbers() {
unsigned DFSNum = 0;
SmallVector<std::pair<DomTreeNodeBase<NodeT>*,
typename DomTreeNodeBase<NodeT>::iterator>, 32> WorkStack;
for (unsigned i = 0, e = (unsigned)this->Roots.size(); i != e; ++i) {
DomTreeNodeBase<NodeT> *ThisRoot = getNode(this->Roots[i]);
WorkStack.push_back(std::make_pair(ThisRoot, ThisRoot->begin()));
ThisRoot->DFSNumIn = DFSNum++;
while (!WorkStack.empty()) {
DomTreeNodeBase<NodeT> *Node = WorkStack.back().first;
typename DomTreeNodeBase<NodeT>::iterator ChildIt =
WorkStack.back().second;
// If we visited all of the children of this node, "recurse" back up the
// stack setting the DFOutNum.
if (ChildIt == Node->end()) {
Node->DFSNumOut = DFSNum++;
WorkStack.pop_back();
} else {
// Otherwise, recursively visit this child.
DomTreeNodeBase<NodeT> *Child = *ChildIt;
++WorkStack.back().second;
WorkStack.push_back(std::make_pair(Child, Child->begin()));
Child->DFSNumIn = DFSNum++;
}
}
}
SlowQueries = 0;
DFSInfoValid = true;
}
DomTreeNodeBase<NodeT> *getNodeForBlock(NodeT *BB) {
typename DomTreeNodeMapType::iterator I = this->DomTreeNodes.find(BB);
if (I != this->DomTreeNodes.end() && I->second)
return I->second;
// Haven't calculated this node yet? Get or calculate the node for the
// immediate dominator.
NodeT *IDom = getIDom(BB);
assert(IDom || this->DomTreeNodes[NULL]);
DomTreeNodeBase<NodeT> *IDomNode = getNodeForBlock(IDom);
// Add a new tree node for this BasicBlock, and link it as a child of
// IDomNode
DomTreeNodeBase<NodeT> *C = new DomTreeNodeBase<NodeT>(BB, IDomNode);
return this->DomTreeNodes[BB] = IDomNode->addChild(C);
}
inline NodeT *getIDom(NodeT *BB) const {
typename DenseMap<NodeT*, NodeT*>::const_iterator I = IDoms.find(BB);
return I != IDoms.end() ? I->second : 0;
}
inline void addRoot(NodeT* BB) {
this->Roots.push_back(BB);
}
public:
/// recalculate - compute a dominator tree for the given function
template<class FT>
void recalculate(FT& F) {
if (!this->IsPostDominators) {
reset();
// Initialize roots
this->Roots.push_back(&F.front());
this->IDoms[&F.front()] = 0;
this->DomTreeNodes[&F.front()] = 0;
this->Vertex.push_back(0);
Calculate<FT, NodeT*>(*this, F);
updateDFSNumbers();
} else {
reset(); // Reset from the last time we were run...
// Initialize the roots list
for (typename FT::iterator I = F.begin(), E = F.end(); I != E; ++I) {
if (std::distance(GraphTraits<FT*>::child_begin(I),
GraphTraits<FT*>::child_end(I)) == 0)
addRoot(I);
// Prepopulate maps so that we don't get iterator invalidation issues later.
this->IDoms[I] = 0;
this->DomTreeNodes[I] = 0;
}
this->Vertex.push_back(0);
Calculate<FT, Inverse<NodeT*> >(*this, F);
}
}
};
EXTERN_TEMPLATE_INSTANTIATION(class DominatorTreeBase<BasicBlock>);
//===-------------------------------------
/// DominatorTree Class - Concrete subclass of DominatorTreeBase that is used to
/// compute a normal dominator tree.
///
class DominatorTree : public FunctionPass {
public:
static char ID; // Pass ID, replacement for typeid
DominatorTreeBase<BasicBlock>* DT;
DominatorTree() : FunctionPass(&ID) {
DT = new DominatorTreeBase<BasicBlock>(false);
}
~DominatorTree() {
DT->releaseMemory();
delete DT;
}
DominatorTreeBase<BasicBlock>& getBase() { return *DT; }
/// 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 DT->getRoots();
}
inline BasicBlock *getRoot() const {
return DT->getRoot();
}
inline DomTreeNode *getRootNode() const {
return DT->getRootNode();
}
/// compare - Return false if the other dominator tree matches this
/// dominator tree. Otherwise return true.
inline bool compare(DominatorTree &Other) const {
DomTreeNode *R = getRootNode();
DomTreeNode *OtherR = Other.getRootNode();
if (!R || !OtherR || R->getBlock() != OtherR->getBlock())
return true;
if (DT->compare(Other.getBase()))
return true;
return false;
}
virtual bool runOnFunction(Function &F);
virtual void getAnalysisUsage(AnalysisUsage &AU) const {
AU.setPreservesAll();
}
inline bool dominates(DomTreeNode* A, DomTreeNode* B) const {
return DT->dominates(A, B);
}
inline bool dominates(const BasicBlock* A, const BasicBlock* B) const {
return DT->dominates(A, B);
}
// 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(const Instruction *A, const Instruction *B) const {
const BasicBlock *BBA = A->getParent(), *BBB = B->getParent();
if (BBA != BBB) return dominates(BBA, BBB);
// It is not possible to determine dominance between two PHI nodes
// based on their ordering.
if (isa<PHINode>(A) && isa<PHINode>(B))
return false;
// Loop through the basic block until we find A or B.
BasicBlock::const_iterator I = BBA->begin();
for (; &*I != A && &*I != B; ++I) /*empty*/;
//if(!DT.IsPostDominators) {
// A dominates B if it is found first in the basic block.
return &*I == A;
//} else {
// // A post-dominates B if B is found first in the basic block.
// return &*I == B;
//}
}
inline bool properlyDominates(const DomTreeNode* A,
const DomTreeNode* B) const {
return DT->properlyDominates(A, B);
}
inline bool properlyDominates(BasicBlock* A, BasicBlock* B) const {
return DT->properlyDominates(A, B);
}
/// findNearestCommonDominator - Find nearest common dominator basic block
/// for basic block A and B. If there is no such block then return NULL.
inline BasicBlock *findNearestCommonDominator(BasicBlock *A, BasicBlock *B) {
return DT->findNearestCommonDominator(A, B);
}
inline DomTreeNode *operator[](BasicBlock *BB) const {
return DT->getNode(BB);
}
/// getNode - return the (Post)DominatorTree node for the specified basic
/// block. This is the same as using operator[] on this class.
///
inline DomTreeNode *getNode(BasicBlock *BB) const {
return DT->getNode(BB);
}
/// addNewBlock - Add a new node to the dominator tree information. This
/// creates a new node as a child of DomBB dominator node,linking it into
/// the children list of the immediate dominator.
inline DomTreeNode *addNewBlock(BasicBlock *BB, BasicBlock *DomBB) {
return DT->addNewBlock(BB, DomBB);
}
/// changeImmediateDominator - This method is used to update the dominator
/// tree information when a node's immediate dominator changes.
///
inline void changeImmediateDominator(BasicBlock *N, BasicBlock* NewIDom) {
DT->changeImmediateDominator(N, NewIDom);
}
inline void changeImmediateDominator(DomTreeNode *N, DomTreeNode* NewIDom) {
DT->changeImmediateDominator(N, NewIDom);
}
/// eraseNode - Removes a node from the dominator tree. Block must not
/// domiante any other blocks. Removes node from its immediate dominator's
/// children list. Deletes dominator node associated with basic block BB.
inline void eraseNode(BasicBlock *BB) {
DT->eraseNode(BB);
}
/// splitBlock - BB is split and now it has one successor. Update dominator
/// tree to reflect this change.
inline void splitBlock(BasicBlock* NewBB) {
DT->splitBlock(NewBB);
}
bool isReachableFromEntry(BasicBlock* A) {
return DT->isReachableFromEntry(A);
}
virtual void releaseMemory() {
DT->releaseMemory();
}
virtual void print(raw_ostream &OS, const Module* M= 0) const;
};
//===-------------------------------------
/// DominatorTree GraphTraits specialization so the DominatorTree can be
/// iterable by generic graph iterators.
///
template <> struct GraphTraits<DomTreeNode *> {
typedef DomTreeNode 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<DomTreeNode *> {
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 FunctionPass {
public:
typedef std::set<BasicBlock*> DomSetType; // Dom set for a bb
typedef std::map<BasicBlock*, DomSetType> DomSetMapType; // Dom set map
protected:
DomSetMapType Frontiers;
std::vector<BasicBlock*> Roots;
const bool IsPostDominators;
public:
DominanceFrontierBase(void *ID, bool isPostDom)
: FunctionPass(ID), IsPostDominators(isPostDom) {}
/// 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; }
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));
}
/// removeBlock - Remove basic block BB's frontier.
void removeBlock(BasicBlock *BB) {
assert(find(BB) != end() && "Block is not in DominanceFrontier!");
for (iterator I = begin(), E = end(); I != E; ++I)
I->second.erase(BB);
Frontiers.erase(BB);
}
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);
}
/// compareDomSet - Return false if two domsets match. Otherwise
/// return true;
bool compareDomSet(DomSetType &DS1, const DomSetType &DS2) const {
std::set<BasicBlock *> tmpSet;
for (DomSetType::const_iterator I = DS2.begin(),
E = DS2.end(); I != E; ++I)
tmpSet.insert(*I);
for (DomSetType::const_iterator I = DS1.begin(),
E = DS1.end(); I != E; ) {
BasicBlock *Node = *I++;
if (tmpSet.erase(Node) == 0)
// Node is in DS1 but not in DS2.
return true;
}
if(!tmpSet.empty())
// There are nodes that are in DS2 but not in DS1.
return true;
// DS1 and DS2 matches.
return false;
}
/// compare - Return true if the other dominance frontier base matches
/// this dominance frontier base. Otherwise return false.
bool compare(DominanceFrontierBase &Other) const {
DomSetMapType tmpFrontiers;
for (DomSetMapType::const_iterator I = Other.begin(),
E = Other.end(); I != E; ++I)
tmpFrontiers.insert(std::make_pair(I->first, I->second));
for (DomSetMapType::iterator I = tmpFrontiers.begin(),
E = tmpFrontiers.end(); I != E; ) {
BasicBlock *Node = I->first;
const_iterator DFI = find(Node);
if (DFI == end())
return true;
if (compareDomSet(I->second, DFI->second))
return true;
++I;
tmpFrontiers.erase(Node);
}
if (!tmpFrontiers.empty())
return true;
return false;
}
/// print - Convert to human readable form
///
virtual void print(raw_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:
static char ID; // Pass ID, replacement for typeid
DominanceFrontier() :
DominanceFrontierBase(&ID, 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>();
}
/// splitBlock - BB is split and now it has one successor. Update dominance
/// frontier to reflect this change.
void splitBlock(BasicBlock *BB);
/// BasicBlock BB's new dominator is NewBB. Update BB's dominance frontier
/// to reflect this change.
void changeImmediateDominator(BasicBlock *BB, BasicBlock *NewBB,
DominatorTree *DT) {
// NewBB is now dominating BB. Which means BB's dominance
// frontier is now part of NewBB's dominance frontier. However, BB
// itself is not member of NewBB's dominance frontier.
DominanceFrontier::iterator NewDFI = find(NewBB);
DominanceFrontier::iterator DFI = find(BB);
// If BB was an entry block then its frontier is empty.
if (DFI == end())
return;
DominanceFrontier::DomSetType BBSet = DFI->second;
for (DominanceFrontier::DomSetType::iterator BBSetI = BBSet.begin(),
BBSetE = BBSet.end(); BBSetI != BBSetE; ++BBSetI) {
BasicBlock *DFMember = *BBSetI;
// Insert only if NewBB dominates DFMember.
if (!DT->dominates(NewBB, DFMember))
NewDFI->second.insert(DFMember);
}
NewDFI->second.erase(BB);
}
const DomSetType &calculate(const DominatorTree &DT,
const DomTreeNode *Node);
};
} // End llvm namespace
#endif
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