1 //===- llvm/Analysis/Dominators.h - Dominator Info Calculation ---*- C++ -*--=//
3 // This file defines the following classes:
4 // 1. DominatorSet: Calculates the [reverse] dominator set for a function
5 // 2. ImmediateDominators: Calculates and holds a mapping between BasicBlocks
6 // and their immediate dominator.
7 // 3. DominatorTree: Represent the ImmediateDominator as an explicit tree
9 // 4. DominanceFrontier: Calculate and hold the dominance frontier for a
12 // These data structures are listed in increasing order of complexity. It
13 // takes longer to calculate the dominator frontier, for example, than the
14 // ImmediateDominator mapping.
16 //===----------------------------------------------------------------------===//
18 #ifndef LLVM_ANALYSIS_DOMINATORS_H
19 #define LLVM_ANALYSIS_DOMINATORS_H
21 #include "llvm/Pass.h"
25 //===----------------------------------------------------------------------===//
27 // DominatorBase - Base class that other, more interesting dominator analyses
30 class DominatorBase : public FunctionPass {
33 const bool IsPostDominators;
35 inline DominatorBase(bool isPostDom) : Root(0), IsPostDominators(isPostDom) {}
37 inline BasicBlock *getRoot() const { return Root; }
39 // Returns true if analysis based of postdoms
40 bool isPostDominator() const { return IsPostDominators; }
43 //===----------------------------------------------------------------------===//
45 // DominatorSet - Maintain a set<BasicBlock*> for every basic block in a
46 // function, that represents the blocks that dominate the block.
48 class DominatorSetBase : public DominatorBase {
50 typedef std::set<BasicBlock*> DomSetType; // Dom set for a bb
52 typedef std::map<BasicBlock*, DomSetType> DomSetMapType;
56 DominatorSetBase(bool isPostDom) : DominatorBase(isPostDom) {}
58 virtual void releaseMemory() { Doms.clear(); }
60 // Accessor interface:
61 typedef DomSetMapType::const_iterator const_iterator;
62 typedef DomSetMapType::iterator iterator;
63 inline const_iterator begin() const { return Doms.begin(); }
64 inline iterator begin() { return Doms.begin(); }
65 inline const_iterator end() const { return Doms.end(); }
66 inline iterator end() { return Doms.end(); }
67 inline const_iterator find(BasicBlock* B) const { return Doms.find(B); }
68 inline iterator find(BasicBlock* B) { return Doms.find(B); }
71 /// getDominators - Return the set of basic blocks that dominate the specified
74 inline const DomSetType &getDominators(BasicBlock *BB) const {
75 const_iterator I = find(BB);
76 assert(I != end() && "BB not in function!");
80 /// dominates - Return true if A dominates B.
82 inline bool dominates(BasicBlock *A, BasicBlock *B) const {
83 return getDominators(B).count(A) != 0;
86 /// properlyDominates - Return true if A dominates B and A != B.
88 bool properlyDominates(BasicBlock *A, BasicBlock *B) const {
89 return dominates(A, B) && A != B;
92 /// print - Convert to human readable form
93 virtual void print(std::ostream &OS) const;
95 /// dominates - Return true if A dominates B. This performs the special
96 /// checks neccesary if A and B are in the same basic block.
98 bool dominates(Instruction *A, Instruction *B) const;
100 //===--------------------------------------------------------------------===//
101 // API to update (Post)DominatorSet information based on modifications to
104 /// addBasicBlock - Call to update the dominator set with information about a
105 /// new block that was inserted into the function.
106 void addBasicBlock(BasicBlock *BB, const DomSetType &Dominators) {
107 assert(find(BB) == end() && "Block already in DominatorSet!");
108 Doms.insert(std::make_pair(BB, Dominators));
111 // addDominator - If a new block is inserted into the CFG, then method may be
112 // called to notify the blocks it dominates that it is in their set.
114 void addDominator(BasicBlock *BB, BasicBlock *NewDominator) {
115 iterator I = find(BB);
116 assert(I != end() && "BB is not in DominatorSet!");
117 I->second.insert(NewDominator);
122 //===-------------------------------------
123 // DominatorSet Class - Concrete subclass of DominatorSetBase that is used to
124 // compute a normal dominator set.
126 struct DominatorSet : public DominatorSetBase {
127 DominatorSet() : DominatorSetBase(false) {}
129 virtual bool runOnFunction(Function &F);
131 // getAnalysisUsage - This simply provides a dominator set
132 virtual void getAnalysisUsage(AnalysisUsage &AU) const {
133 AU.setPreservesAll();
136 void calculateDominatorsFromBlock(BasicBlock *BB);
140 //===----------------------------------------------------------------------===//
142 // ImmediateDominators - Calculate the immediate dominator for each node in a
145 class ImmediateDominatorsBase : public DominatorBase {
147 std::map<BasicBlock*, BasicBlock*> IDoms;
148 void calcIDoms(const DominatorSetBase &DS);
150 ImmediateDominatorsBase(bool isPostDom) : DominatorBase(isPostDom) {}
152 virtual void releaseMemory() { IDoms.clear(); }
154 // Accessor interface:
155 typedef std::map<BasicBlock*, BasicBlock*> IDomMapType;
156 typedef IDomMapType::const_iterator const_iterator;
157 inline const_iterator begin() const { return IDoms.begin(); }
158 inline const_iterator end() const { return IDoms.end(); }
159 inline const_iterator find(BasicBlock* B) const { return IDoms.find(B);}
161 // operator[] - Return the idom for the specified basic block. The start
162 // node returns null, because it does not have an immediate dominator.
164 inline BasicBlock *operator[](BasicBlock *BB) const {
168 // get() - Synonym for operator[].
169 inline BasicBlock *get(BasicBlock *BB) const {
170 std::map<BasicBlock*, BasicBlock*>::const_iterator I = IDoms.find(BB);
171 return I != IDoms.end() ? I->second : 0;
174 //===--------------------------------------------------------------------===//
175 // API to update Immediate(Post)Dominators information based on modifications
178 /// addNewBlock - Add a new block to the CFG, with the specified immediate
181 void addNewBlock(BasicBlock *BB, BasicBlock *IDom) {
182 assert(get(BB) == 0 && "BasicBlock already in idom info!");
187 // print - Convert to human readable form
188 virtual void print(std::ostream &OS) const;
191 //===-------------------------------------
192 // ImmediateDominators Class - Concrete subclass of ImmediateDominatorsBase that
193 // is used to compute a normal immediate dominator set.
195 struct ImmediateDominators : public ImmediateDominatorsBase {
196 ImmediateDominators() : ImmediateDominatorsBase(false) {}
198 virtual bool runOnFunction(Function &F) {
199 IDoms.clear(); // Reset from the last time we were run...
200 DominatorSet &DS = getAnalysis<DominatorSet>();
206 virtual void getAnalysisUsage(AnalysisUsage &AU) const {
207 AU.setPreservesAll();
208 AU.addRequired<DominatorSet>();
213 //===----------------------------------------------------------------------===//
215 // DominatorTree - Calculate the immediate dominator tree for a function.
217 class DominatorTreeBase : public DominatorBase {
223 std::map<BasicBlock*, Node*> Nodes;
225 typedef std::map<BasicBlock*, Node*> NodeMapType;
227 class Node2 : public std::vector<Node*> {
228 friend class DominatorTree;
229 friend class PostDominatorTree;
230 friend class DominatorTreeBase;
234 inline BasicBlock *getNode() const { return TheNode; }
235 inline Node2 *getIDom() const { return IDom; }
236 inline const std::vector<Node*> &getChildren() const { return *this; }
238 // dominates - Returns true iff this dominates N. Note that this is not a
239 // constant time operation!
240 inline bool dominates(const Node2 *N) const {
242 while ((IDom = N->getIDom()) != 0 && IDom != this)
243 N = IDom; // Walk up the tree
248 inline Node2(BasicBlock *node, Node *iDom)
249 : TheNode(node), IDom(iDom) {}
250 inline Node2 *addChild(Node *C) { push_back(C); return C; }
254 DominatorTreeBase(bool isPostDom) : DominatorBase(isPostDom) {}
255 ~DominatorTreeBase() { reset(); }
257 virtual void releaseMemory() { reset(); }
259 /// getNode - return the (Post)DominatorTree node for the specified basic
260 /// block. This is the same as using operator[] on this class.
262 inline Node *getNode(BasicBlock *BB) const {
263 NodeMapType::const_iterator i = Nodes.find(BB);
264 return (i != Nodes.end()) ? i->second : 0;
267 inline Node *operator[](BasicBlock *BB) const {
271 // API to update (Post)DominatorTree information based on modifications to
274 /// createNewNode - Add a new node to the dominator tree information. This
275 /// creates a new node as a child of IDomNode, linking it into the children
276 /// list of the immediate dominator.
278 Node *createNewNode(BasicBlock *BB, Node *IDomNode) {
279 assert(getNode(BB) == 0 && "Block already in dominator tree!");
280 Node *New = Nodes[BB] = new Node(BB, IDomNode);
281 if (IDomNode) IDomNode->addChild(New);
285 /// print - Convert to human readable form
286 virtual void print(std::ostream &OS) const;
290 //===-------------------------------------
291 // DominatorTree Class - Concrete subclass of DominatorTreeBase that is used to
292 // compute a normal dominator tree.
294 struct DominatorTree : public DominatorTreeBase {
295 DominatorTree() : DominatorTreeBase(false) {}
297 virtual bool runOnFunction(Function &F) {
298 reset(); // Reset from the last time we were run...
299 DominatorSet &DS = getAnalysis<DominatorSet>();
305 virtual void getAnalysisUsage(AnalysisUsage &AU) const {
306 AU.setPreservesAll();
307 AU.addRequired<DominatorSet>();
310 void calculate(const DominatorSet &DS);
314 //===----------------------------------------------------------------------===//
316 // DominanceFrontier - Calculate the dominance frontiers for a function.
318 class DominanceFrontierBase : public DominatorBase {
320 typedef std::set<BasicBlock*> DomSetType; // Dom set for a bb
321 typedef std::map<BasicBlock*, DomSetType> DomSetMapType; // Dom set map
323 DomSetMapType Frontiers;
325 DominanceFrontierBase(bool isPostDom) : DominatorBase(isPostDom) {}
327 virtual void releaseMemory() { Frontiers.clear(); }
329 // Accessor interface:
330 typedef DomSetMapType::const_iterator const_iterator;
331 inline const_iterator begin() const { return Frontiers.begin(); }
332 inline const_iterator end() const { return Frontiers.end(); }
333 inline const_iterator find(BasicBlock* B) const { return Frontiers.find(B); }
335 // print - Convert to human readable form
336 virtual void print(std::ostream &OS) const;
340 //===-------------------------------------
341 // DominatorTree Class - Concrete subclass of DominatorTreeBase that is used to
342 // compute a normal dominator tree.
344 struct DominanceFrontier : public DominanceFrontierBase {
345 DominanceFrontier() : DominanceFrontierBase(false) {}
347 virtual bool runOnFunction(Function &) {
349 DominatorTree &DT = getAnalysis<DominatorTree>();
351 calculate(DT, DT[Root]);
355 virtual void getAnalysisUsage(AnalysisUsage &AU) const {
356 AU.setPreservesAll();
357 AU.addRequired<DominatorTree>();
360 const DomSetType &calculate(const DominatorTree &DT,
361 const DominatorTree::Node *Node);