1 //===-- llvm/Support/CFG.h - Process LLVM structures as graphs --*- C++ -*-===// 2 // 3 // The LLVM Compiler Infrastructure 4 // 5 // This file is distributed under the University of Illinois Open Source 6 // License. See LICENSE.TXT for details. 7 // 8 //===----------------------------------------------------------------------===// 9 // 10 // This file defines specializations of GraphTraits that allow Function and 11 // BasicBlock graphs to be treated as proper graphs for generic algorithms. 12 // 13 //===----------------------------------------------------------------------===// 14 15 #ifndef LLVM_SUPPORT_CFG_H 16 #define LLVM_SUPPORT_CFG_H 17 18 #include "llvm/ADT/GraphTraits.h" 19 #include "llvm/IR/Function.h" 20 #include "llvm/IR/InstrTypes.h" 21 22 namespace llvm { 23 24 //===----------------------------------------------------------------------===// 25 // BasicBlock pred_iterator definition 26 //===----------------------------------------------------------------------===// 27 28 template <class Ptr, class USE_iterator> // Predecessor Iterator 29 class PredIterator : public std::iterator<std::forward_iterator_tag, 30 Ptr, ptrdiff_t> { 31 typedef std::iterator<std::forward_iterator_tag, Ptr, ptrdiff_t> super; 32 typedef PredIterator<Ptr, USE_iterator> Self; 33 USE_iterator It; 34 35 inline void advancePastNonTerminators() { 36 // Loop to ignore non terminator uses (for example BlockAddresses). 37 while (!It.atEnd() && !isa<TerminatorInst>(*It)) 38 ++It; 39 } 40 41 public: 42 typedef typename super::pointer pointer; 43 44 PredIterator() {} 45 explicit inline PredIterator(Ptr *bb) : It(bb->use_begin()) { 46 advancePastNonTerminators(); 47 } 48 inline PredIterator(Ptr *bb, bool) : It(bb->use_end()) {} 49 50 inline bool operator==(const Self& x) const { return It == x.It; } 51 inline bool operator!=(const Self& x) const { return !operator==(x); } 52 53 inline pointer operator*() const { 54 assert(!It.atEnd() && "pred_iterator out of range!"); 55 return cast<TerminatorInst>(*It)->getParent(); 56 } 57 inline pointer *operator->() const { return &operator*(); } 58 59 inline Self& operator++() { // Preincrement 60 assert(!It.atEnd() && "pred_iterator out of range!"); 61 ++It; advancePastNonTerminators(); 62 return *this; 63 } 64 65 inline Self operator++(int) { // Postincrement 66 Self tmp = *this; ++*this; return tmp; 67 } 68 69 /// getOperandNo - Return the operand number in the predecessor's 70 /// terminator of the successor. 71 unsigned getOperandNo() const { 72 return It.getOperandNo(); 73 } 74 75 /// getUse - Return the operand Use in the predecessor's terminator 76 /// of the successor. 77 Use &getUse() const { 78 return It.getUse(); 79 } 80 }; 81 82 typedef PredIterator<BasicBlock, Value::use_iterator> pred_iterator; 83 typedef PredIterator<const BasicBlock, 84 Value::const_use_iterator> const_pred_iterator; 85 86 inline pred_iterator pred_begin(BasicBlock *BB) { return pred_iterator(BB); } 87 inline const_pred_iterator pred_begin(const BasicBlock *BB) { 88 return const_pred_iterator(BB); 89 } 90 inline pred_iterator pred_end(BasicBlock *BB) { return pred_iterator(BB, true);} 91 inline const_pred_iterator pred_end(const BasicBlock *BB) { 92 return const_pred_iterator(BB, true); 93 } 94 95 96 97 //===----------------------------------------------------------------------===// 98 // BasicBlock succ_iterator definition 99 //===----------------------------------------------------------------------===// 100 101 template <class Term_, class BB_> // Successor Iterator 102 class SuccIterator : public std::iterator<std::bidirectional_iterator_tag, 103 BB_, ptrdiff_t> { 104 const Term_ Term; 105 unsigned idx; 106 typedef std::iterator<std::bidirectional_iterator_tag, BB_, ptrdiff_t> super; 107 typedef SuccIterator<Term_, BB_> Self; 108 109 inline bool index_is_valid(int idx) { 110 return idx >= 0 && (unsigned) idx < Term->getNumSuccessors(); 111 } 112 113 public: 114 typedef typename super::pointer pointer; 115 // TODO: This can be random access iterator, only operator[] missing. 116 117 explicit inline SuccIterator(Term_ T) : Term(T), idx(0) {// begin iterator 118 } 119 inline SuccIterator(Term_ T, bool) // end iterator 120 : Term(T) { 121 if (Term) 122 idx = Term->getNumSuccessors(); 123 else 124 // Term == NULL happens, if a basic block is not fully constructed and 125 // consequently getTerminator() returns NULL. In this case we construct a 126 // SuccIterator which describes a basic block that has zero successors. 127 // Defining SuccIterator for incomplete and malformed CFGs is especially 128 // useful for debugging. 129 idx = 0; 130 } 131 132 inline const Self &operator=(const Self &I) { 133 assert(Term == I.Term &&"Cannot assign iterators to two different blocks!"); 134 idx = I.idx; 135 return *this; 136 } 137 138 /// getSuccessorIndex - This is used to interface between code that wants to 139 /// operate on terminator instructions directly. 140 unsigned getSuccessorIndex() const { return idx; } 141 142 inline bool operator==(const Self& x) const { return idx == x.idx; } 143 inline bool operator!=(const Self& x) const { return !operator==(x); } 144 145 inline pointer operator*() const { return Term->getSuccessor(idx); } 146 inline pointer operator->() const { return operator*(); } 147 148 inline Self& operator++() { ++idx; return *this; } // Preincrement 149 150 inline Self operator++(int) { // Postincrement 151 Self tmp = *this; ++*this; return tmp; 152 } 153 154 inline Self& operator--() { --idx; return *this; } // Predecrement 155 inline Self operator--(int) { // Postdecrement 156 Self tmp = *this; --*this; return tmp; 157 } 158 159 inline bool operator<(const Self& x) const { 160 assert(Term == x.Term && "Cannot compare iterators of different blocks!"); 161 return idx < x.idx; 162 } 163 164 inline bool operator<=(const Self& x) const { 165 assert(Term == x.Term && "Cannot compare iterators of different blocks!"); 166 return idx <= x.idx; 167 } 168 inline bool operator>=(const Self& x) const { 169 assert(Term == x.Term && "Cannot compare iterators of different blocks!"); 170 return idx >= x.idx; 171 } 172 173 inline bool operator>(const Self& x) const { 174 assert(Term == x.Term && "Cannot compare iterators of different blocks!"); 175 return idx > x.idx; 176 } 177 178 inline Self& operator+=(int Right) { 179 unsigned new_idx = idx + Right; 180 assert(index_is_valid(new_idx) && "Iterator index out of bound"); 181 idx = new_idx; 182 return *this; 183 } 184 185 inline Self operator+(int Right) { 186 Self tmp = *this; 187 tmp += Right; 188 return tmp; 189 } 190 191 inline Self& operator-=(int Right) { 192 return operator+=(-Right); 193 } 194 195 inline Self operator-(int Right) { 196 return operator+(-Right); 197 } 198 199 inline int operator-(const Self& x) { 200 assert(Term == x.Term && "Cannot work on iterators of different blocks!"); 201 int distance = idx - x.idx; 202 return distance; 203 } 204 205 // This works for read access, however write access is difficult as changes 206 // to Term are only possible with Term->setSuccessor(idx). Pointers that can 207 // be modified are not available. 208 // 209 // inline pointer operator[](int offset) { 210 // Self tmp = *this; 211 // tmp += offset; 212 // return tmp.operator*(); 213 // } 214 215 /// Get the source BB of this iterator. 216 inline BB_ *getSource() { 217 assert(Term && "Source not available, if basic block was malformed"); 218 return Term->getParent(); 219 } 220 }; 221 222 typedef SuccIterator<TerminatorInst*, BasicBlock> succ_iterator; 223 typedef SuccIterator<const TerminatorInst*, 224 const BasicBlock> succ_const_iterator; 225 226 inline succ_iterator succ_begin(BasicBlock *BB) { 227 return succ_iterator(BB->getTerminator()); 228 } 229 inline succ_const_iterator succ_begin(const BasicBlock *BB) { 230 return succ_const_iterator(BB->getTerminator()); 231 } 232 inline succ_iterator succ_end(BasicBlock *BB) { 233 return succ_iterator(BB->getTerminator(), true); 234 } 235 inline succ_const_iterator succ_end(const BasicBlock *BB) { 236 return succ_const_iterator(BB->getTerminator(), true); 237 } 238 239 240 241 //===--------------------------------------------------------------------===// 242 // GraphTraits specializations for basic block graphs (CFGs) 243 //===--------------------------------------------------------------------===// 244 245 // Provide specializations of GraphTraits to be able to treat a function as a 246 // graph of basic blocks... 247 248 template <> struct GraphTraits<BasicBlock*> { 249 typedef BasicBlock NodeType; 250 typedef succ_iterator ChildIteratorType; 251 252 static NodeType *getEntryNode(BasicBlock *BB) { return BB; } 253 static inline ChildIteratorType child_begin(NodeType *N) { 254 return succ_begin(N); 255 } 256 static inline ChildIteratorType child_end(NodeType *N) { 257 return succ_end(N); 258 } 259 }; 260 261 template <> struct GraphTraits<const BasicBlock*> { 262 typedef const BasicBlock NodeType; 263 typedef succ_const_iterator ChildIteratorType; 264 265 static NodeType *getEntryNode(const BasicBlock *BB) { return BB; } 266 267 static inline ChildIteratorType child_begin(NodeType *N) { 268 return succ_begin(N); 269 } 270 static inline ChildIteratorType child_end(NodeType *N) { 271 return succ_end(N); 272 } 273 }; 274 275 // Provide specializations of GraphTraits to be able to treat a function as a 276 // graph of basic blocks... and to walk it in inverse order. Inverse order for 277 // a function is considered to be when traversing the predecessor edges of a BB 278 // instead of the successor edges. 279 // 280 template <> struct GraphTraits<Inverse<BasicBlock*> > { 281 typedef BasicBlock NodeType; 282 typedef pred_iterator ChildIteratorType; 283 static NodeType *getEntryNode(Inverse<BasicBlock *> G) { return G.Graph; } 284 static inline ChildIteratorType child_begin(NodeType *N) { 285 return pred_begin(N); 286 } 287 static inline ChildIteratorType child_end(NodeType *N) { 288 return pred_end(N); 289 } 290 }; 291 292 template <> struct GraphTraits<Inverse<const BasicBlock*> > { 293 typedef const BasicBlock NodeType; 294 typedef const_pred_iterator ChildIteratorType; 295 static NodeType *getEntryNode(Inverse<const BasicBlock*> G) { 296 return G.Graph; 297 } 298 static inline ChildIteratorType child_begin(NodeType *N) { 299 return pred_begin(N); 300 } 301 static inline ChildIteratorType child_end(NodeType *N) { 302 return pred_end(N); 303 } 304 }; 305 306 307 308 //===--------------------------------------------------------------------===// 309 // GraphTraits specializations for function basic block graphs (CFGs) 310 //===--------------------------------------------------------------------===// 311 312 // Provide specializations of GraphTraits to be able to treat a function as a 313 // graph of basic blocks... these are the same as the basic block iterators, 314 // except that the root node is implicitly the first node of the function. 315 // 316 template <> struct GraphTraits<Function*> : public GraphTraits<BasicBlock*> { 317 static NodeType *getEntryNode(Function *F) { return &F->getEntryBlock(); } 318 319 // nodes_iterator/begin/end - Allow iteration over all nodes in the graph 320 typedef Function::iterator nodes_iterator; 321 static nodes_iterator nodes_begin(Function *F) { return F->begin(); } 322 static nodes_iterator nodes_end (Function *F) { return F->end(); } 323 static unsigned size (Function *F) { return F->size(); } 324 }; 325 template <> struct GraphTraits<const Function*> : 326 public GraphTraits<const BasicBlock*> { 327 static NodeType *getEntryNode(const Function *F) {return &F->getEntryBlock();} 328 329 // nodes_iterator/begin/end - Allow iteration over all nodes in the graph 330 typedef Function::const_iterator nodes_iterator; 331 static nodes_iterator nodes_begin(const Function *F) { return F->begin(); } 332 static nodes_iterator nodes_end (const Function *F) { return F->end(); } 333 static unsigned size (const Function *F) { return F->size(); } 334 }; 335 336 337 // Provide specializations of GraphTraits to be able to treat a function as a 338 // graph of basic blocks... and to walk it in inverse order. Inverse order for 339 // a function is considered to be when traversing the predecessor edges of a BB 340 // instead of the successor edges. 341 // 342 template <> struct GraphTraits<Inverse<Function*> > : 343 public GraphTraits<Inverse<BasicBlock*> > { 344 static NodeType *getEntryNode(Inverse<Function*> G) { 345 return &G.Graph->getEntryBlock(); 346 } 347 }; 348 template <> struct GraphTraits<Inverse<const Function*> > : 349 public GraphTraits<Inverse<const BasicBlock*> > { 350 static NodeType *getEntryNode(Inverse<const Function *> G) { 351 return &G.Graph->getEntryBlock(); 352 } 353 }; 354 355 } // End llvm namespace 356 357 #endif 358