-//===- llvm/Analysis/Dominators.h - Dominator Info Calculation ---*- C++ -*--=//
+//===- llvm/Analysis/Dominators.h - Dominator Info Calculation --*- C++ -*-===//
//
// This file defines the following classes:
// 1. DominatorSet: Calculates the [reverse] dominator set for a function
#include "llvm/Pass.h"
#include <set>
+
class Instruction;
+template <typename GraphType> struct GraphTraits;
+
//===----------------------------------------------------------------------===//
//
// DominatorBase - Base class that other, more interesting dominator analyses
//
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; }
+ // 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
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.
+// 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:
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 {
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;
virtual bool runOnFunction(Function &F);
+ /// recalculate - This method may be called by external passes that modify the
+ /// CFG and then need dominator information recalculated. This method is
+ /// obviously really slow, so it should be avoided if at all possible.
+ void recalculate();
+
+ 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.setPreservesAll();
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;
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) {
IDoms.clear(); // Reset from the last time we were run...
DominatorSet &DS = getAnalysis<DominatorSet>();
- Root = DS.getRoot();
+ Roots = DS.getRoots();
calcIDoms(DS);
return false;
}
std::map<BasicBlock*, Node*> Nodes;
void reset();
typedef std::map<BasicBlock*, Node*> NodeMapType;
+
+ Node *RootNode;
public:
- class Node2 : public std::vector<Node*> {
+ class Node2 {
friend class DominatorTree;
friend class PostDominatorTree;
friend class DominatorTreeBase;
BasicBlock *TheNode;
Node2 *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 *getNode() const { return TheNode; }
inline Node2 *getIDom() const { return IDom; }
- inline const std::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!
private:
inline Node2(BasicBlock *node, Node *iDom)
: TheNode(node), IDom(iDom) {}
- inline Node2 *addChild(Node *C) { push_back(C); return C; }
+ inline Node2 *addChild(Node *C) { Children.push_back(C); return C; }
+
+ void setIDom(Node2 *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
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();
+ Roots = DS.getRoots();
calculate(DS);
return false;
}
void calculate(const DominatorSet &DS);
};
+//===-------------------------------------
+// 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();
+ }
+};
//===----------------------------------------------------------------------===//
//
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);
+ }
+
+ 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;
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;
}
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