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));
113 //===-------------------------------------
114 // DominatorSet Class - Concrete subclass of DominatorSetBase that is used to
115 // compute a normal dominator set.
117 struct DominatorSet : public DominatorSetBase {
118 DominatorSet() : DominatorSetBase(false) {}
120 virtual bool runOnFunction(Function &F);
122 // getAnalysisUsage - This simply provides a dominator set
123 virtual void getAnalysisUsage(AnalysisUsage &AU) const {
124 AU.setPreservesAll();
127 void calculateDominatorsFromBlock(BasicBlock *BB);
131 //===----------------------------------------------------------------------===//
133 // ImmediateDominators - Calculate the immediate dominator for each node in a
136 class ImmediateDominatorsBase : public DominatorBase {
138 std::map<BasicBlock*, BasicBlock*> IDoms;
139 void calcIDoms(const DominatorSetBase &DS);
141 ImmediateDominatorsBase(bool isPostDom) : DominatorBase(isPostDom) {}
143 virtual void releaseMemory() { IDoms.clear(); }
145 // Accessor interface:
146 typedef std::map<BasicBlock*, BasicBlock*> IDomMapType;
147 typedef IDomMapType::const_iterator const_iterator;
148 inline const_iterator begin() const { return IDoms.begin(); }
149 inline const_iterator end() const { return IDoms.end(); }
150 inline const_iterator find(BasicBlock* B) const { return IDoms.find(B);}
152 // operator[] - Return the idom for the specified basic block. The start
153 // node returns null, because it does not have an immediate dominator.
155 inline BasicBlock *operator[](BasicBlock *BB) const {
159 // get() - Synonym for operator[].
160 inline BasicBlock *get(BasicBlock *BB) const {
161 std::map<BasicBlock*, BasicBlock*>::const_iterator I = IDoms.find(BB);
162 return I != IDoms.end() ? I->second : 0;
165 //===--------------------------------------------------------------------===//
166 // API to update Immediate(Post)Dominators information based on modifications
169 /// addNewBlock - Add a new block to the CFG, with the specified immediate
172 void addNewBlock(BasicBlock *BB, BasicBlock *IDom) {
173 assert(get(BB) == 0 && "BasicBlock already in idom info!");
178 // print - Convert to human readable form
179 virtual void print(std::ostream &OS) const;
182 //===-------------------------------------
183 // ImmediateDominators Class - Concrete subclass of ImmediateDominatorsBase that
184 // is used to compute a normal immediate dominator set.
186 struct ImmediateDominators : public ImmediateDominatorsBase {
187 ImmediateDominators() : ImmediateDominatorsBase(false) {}
189 virtual bool runOnFunction(Function &F) {
190 IDoms.clear(); // Reset from the last time we were run...
191 DominatorSet &DS = getAnalysis<DominatorSet>();
197 virtual void getAnalysisUsage(AnalysisUsage &AU) const {
198 AU.setPreservesAll();
199 AU.addRequired<DominatorSet>();
204 //===----------------------------------------------------------------------===//
206 // DominatorTree - Calculate the immediate dominator tree for a function.
208 class DominatorTreeBase : public DominatorBase {
214 std::map<BasicBlock*, Node*> Nodes;
216 typedef std::map<BasicBlock*, Node*> NodeMapType;
218 class Node2 : public std::vector<Node*> {
219 friend class DominatorTree;
220 friend class PostDominatorTree;
221 friend class DominatorTreeBase;
225 inline BasicBlock *getNode() const { return TheNode; }
226 inline Node2 *getIDom() const { return IDom; }
227 inline const std::vector<Node*> &getChildren() const { return *this; }
229 // dominates - Returns true iff this dominates N. Note that this is not a
230 // constant time operation!
231 inline bool dominates(const Node2 *N) const {
233 while ((IDom = N->getIDom()) != 0 && IDom != this)
234 N = IDom; // Walk up the tree
239 inline Node2(BasicBlock *node, Node *iDom)
240 : TheNode(node), IDom(iDom) {}
241 inline Node2 *addChild(Node *C) { push_back(C); return C; }
245 DominatorTreeBase(bool isPostDom) : DominatorBase(isPostDom) {}
246 ~DominatorTreeBase() { reset(); }
248 virtual void releaseMemory() { reset(); }
250 /// getNode - return the (Post)DominatorTree node for the specified basic
251 /// block. This is the same as using operator[] on this class.
253 inline Node *getNode(BasicBlock *BB) const {
254 NodeMapType::const_iterator i = Nodes.find(BB);
255 return (i != Nodes.end()) ? i->second : 0;
258 inline Node *operator[](BasicBlock *BB) const {
262 // API to update (Post)DominatorTree information based on modifications to
265 /// createNewNode - Add a new node to the dominator tree information. This
266 /// creates a new node as a child of IDomNode, linking it into the children
267 /// list of the immediate dominator.
269 Node *createNewNode(BasicBlock *BB, Node *IDomNode) {
270 assert(getNode(BB) == 0 && "Block already in dominator tree!");
271 Node *New = Nodes[BB] = new Node(BB, IDomNode);
272 if (IDomNode) IDomNode->addChild(New);
276 /// print - Convert to human readable form
277 virtual void print(std::ostream &OS) const;
281 //===-------------------------------------
282 // DominatorTree Class - Concrete subclass of DominatorTreeBase that is used to
283 // compute a normal dominator tree.
285 struct DominatorTree : public DominatorTreeBase {
286 DominatorTree() : DominatorTreeBase(false) {}
288 virtual bool runOnFunction(Function &F) {
289 reset(); // Reset from the last time we were run...
290 DominatorSet &DS = getAnalysis<DominatorSet>();
296 virtual void getAnalysisUsage(AnalysisUsage &AU) const {
297 AU.setPreservesAll();
298 AU.addRequired<DominatorSet>();
301 void calculate(const DominatorSet &DS);
305 //===----------------------------------------------------------------------===//
307 // DominanceFrontier - Calculate the dominance frontiers for a function.
309 class DominanceFrontierBase : public DominatorBase {
311 typedef std::set<BasicBlock*> DomSetType; // Dom set for a bb
312 typedef std::map<BasicBlock*, DomSetType> DomSetMapType; // Dom set map
314 DomSetMapType Frontiers;
316 DominanceFrontierBase(bool isPostDom) : DominatorBase(isPostDom) {}
318 virtual void releaseMemory() { Frontiers.clear(); }
320 // Accessor interface:
321 typedef DomSetMapType::const_iterator const_iterator;
322 inline const_iterator begin() const { return Frontiers.begin(); }
323 inline const_iterator end() const { return Frontiers.end(); }
324 inline const_iterator find(BasicBlock* B) const { return Frontiers.find(B); }
326 // print - Convert to human readable form
327 virtual void print(std::ostream &OS) const;
331 //===-------------------------------------
332 // DominatorTree Class - Concrete subclass of DominatorTreeBase that is used to
333 // compute a normal dominator tree.
335 struct DominanceFrontier : public DominanceFrontierBase {
336 DominanceFrontier() : DominanceFrontierBase(false) {}
338 virtual bool runOnFunction(Function &) {
340 DominatorTree &DT = getAnalysis<DominatorTree>();
342 calculate(DT, DT[Root]);
346 virtual void getAnalysisUsage(AnalysisUsage &AU) const {
347 AU.setPreservesAll();
348 AU.addRequired<DominatorTree>();
351 const DomSetType &calculate(const DominatorTree &DT,
352 const DominatorTree::Node *Node);