CFG.h revision 208954
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/Function.h" 20#include "llvm/InstrTypes.h" 21 22namespace llvm { 23 24//===----------------------------------------------------------------------===// 25// BasicBlock pred_iterator definition 26//===----------------------------------------------------------------------===// 27 28template <class Ptr, class USE_iterator> // Predecessor Iterator 29class 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 PHI nodes). 37 while (!It.atEnd() && !isa<TerminatorInst>(*It)) 38 ++It; 39 } 40 41public: 42 typedef typename super::pointer pointer; 43 44 explicit inline PredIterator(Ptr *bb) : It(bb->use_begin()) { 45 advancePastNonTerminators(); 46 } 47 inline PredIterator(Ptr *bb, bool) : It(bb->use_end()) {} 48 49 inline bool operator==(const Self& x) const { return It == x.It; } 50 inline bool operator!=(const Self& x) const { return !operator==(x); } 51 52 inline pointer operator*() const { 53 assert(!It.atEnd() && "pred_iterator out of range!"); 54 return cast<TerminatorInst>(*It)->getParent(); 55 } 56 inline pointer *operator->() const { return &(operator*()); } 57 58 inline Self& operator++() { // Preincrement 59 assert(!It.atEnd() && "pred_iterator out of range!"); 60 ++It; advancePastNonTerminators(); 61 return *this; 62 } 63 64 inline Self operator++(int) { // Postincrement 65 Self tmp = *this; ++*this; return tmp; 66 } 67}; 68 69typedef PredIterator<BasicBlock, Value::use_iterator> pred_iterator; 70typedef PredIterator<const BasicBlock, 71 Value::const_use_iterator> const_pred_iterator; 72 73inline pred_iterator pred_begin(BasicBlock *BB) { return pred_iterator(BB); } 74inline const_pred_iterator pred_begin(const BasicBlock *BB) { 75 return const_pred_iterator(BB); 76} 77inline pred_iterator pred_end(BasicBlock *BB) { return pred_iterator(BB, true);} 78inline const_pred_iterator pred_end(const BasicBlock *BB) { 79 return const_pred_iterator(BB, true); 80} 81 82 83 84//===----------------------------------------------------------------------===// 85// BasicBlock succ_iterator definition 86//===----------------------------------------------------------------------===// 87 88template <class Term_, class BB_> // Successor Iterator 89class SuccIterator : public std::iterator<std::bidirectional_iterator_tag, 90 BB_, ptrdiff_t> { 91 const Term_ Term; 92 unsigned idx; 93 typedef std::iterator<std::bidirectional_iterator_tag, BB_, ptrdiff_t> super; 94 typedef SuccIterator<Term_, BB_> Self; 95 96 inline bool index_is_valid(int idx) { 97 return idx >= 0 && (unsigned) idx < Term->getNumSuccessors(); 98 } 99 100public: 101 typedef typename super::pointer pointer; 102 // TODO: This can be random access iterator, only operator[] missing. 103 104 explicit inline SuccIterator(Term_ T) : Term(T), idx(0) {// begin iterator 105 assert(T && "getTerminator returned null!"); 106 } 107 inline SuccIterator(Term_ T, bool) // end iterator 108 : Term(T), idx(Term->getNumSuccessors()) { 109 assert(T && "getTerminator returned null!"); 110 } 111 112 inline const Self &operator=(const Self &I) { 113 assert(Term == I.Term &&"Cannot assign iterators to two different blocks!"); 114 idx = I.idx; 115 return *this; 116 } 117 118 /// getSuccessorIndex - This is used to interface between code that wants to 119 /// operate on terminator instructions directly. 120 unsigned getSuccessorIndex() const { return idx; } 121 122 inline bool operator==(const Self& x) const { return idx == x.idx; } 123 inline bool operator!=(const Self& x) const { return !operator==(x); } 124 125 inline pointer operator*() const { return Term->getSuccessor(idx); } 126 inline pointer operator->() const { return operator*(); } 127 128 inline Self& operator++() { ++idx; return *this; } // Preincrement 129 130 inline Self operator++(int) { // Postincrement 131 Self tmp = *this; ++*this; return tmp; 132 } 133 134 inline Self& operator--() { --idx; return *this; } // Predecrement 135 inline Self operator--(int) { // Postdecrement 136 Self tmp = *this; --*this; return tmp; 137 } 138 139 inline bool operator<(const Self& x) const { 140 assert(Term == x.Term && "Cannot compare iterators of different blocks!"); 141 return idx < x.idx; 142 } 143 144 inline bool operator<=(const Self& x) const { 145 assert(Term == x.Term && "Cannot compare iterators of different blocks!"); 146 return idx <= x.idx; 147 } 148 inline bool operator>=(const Self& x) const { 149 assert(Term == x.Term && "Cannot compare iterators of different blocks!"); 150 return idx >= x.idx; 151 } 152 153 inline bool operator>(const Self& x) const { 154 assert(Term == x.Term && "Cannot compare iterators of different blocks!"); 155 return idx > x.idx; 156 } 157 158 inline Self& operator+=(int Right) { 159 unsigned new_idx = idx + Right; 160 assert(index_is_valid(new_idx) && "Iterator index out of bound"); 161 idx = new_idx; 162 return *this; 163 } 164 165 inline Self operator+(int Right) { 166 Self tmp = *this; 167 tmp += Right; 168 return tmp; 169 } 170 171 inline Self& operator-=(int Right) { 172 return operator+=(-Right); 173 } 174 175 inline Self operator-(int Right) { 176 return operator+(-Right); 177 } 178 179 inline int operator-(const Self& x) { 180 assert(Term == x.Term && "Cannot work on iterators of different blocks!"); 181 int distance = idx - x.idx; 182 return distance; 183 } 184 185 // This works for read access, however write access is difficult as changes 186 // to Term are only possible with Term->setSuccessor(idx). Pointers that can 187 // be modified are not available. 188 // 189 // inline pointer operator[](int offset) { 190 // Self tmp = *this; 191 // tmp += offset; 192 // return tmp.operator*(); 193 // } 194 195 /// Get the source BB of this iterator. 196 inline BB_ *getSource() { 197 return Term->getParent(); 198 } 199}; 200 201typedef SuccIterator<TerminatorInst*, BasicBlock> succ_iterator; 202typedef SuccIterator<const TerminatorInst*, 203 const BasicBlock> succ_const_iterator; 204 205inline succ_iterator succ_begin(BasicBlock *BB) { 206 return succ_iterator(BB->getTerminator()); 207} 208inline succ_const_iterator succ_begin(const BasicBlock *BB) { 209 return succ_const_iterator(BB->getTerminator()); 210} 211inline succ_iterator succ_end(BasicBlock *BB) { 212 return succ_iterator(BB->getTerminator(), true); 213} 214inline succ_const_iterator succ_end(const BasicBlock *BB) { 215 return succ_const_iterator(BB->getTerminator(), true); 216} 217 218 219 220//===--------------------------------------------------------------------===// 221// GraphTraits specializations for basic block graphs (CFGs) 222//===--------------------------------------------------------------------===// 223 224// Provide specializations of GraphTraits to be able to treat a function as a 225// graph of basic blocks... 226 227template <> struct GraphTraits<BasicBlock*> { 228 typedef BasicBlock NodeType; 229 typedef succ_iterator ChildIteratorType; 230 231 static NodeType *getEntryNode(BasicBlock *BB) { return BB; } 232 static inline ChildIteratorType child_begin(NodeType *N) { 233 return succ_begin(N); 234 } 235 static inline ChildIteratorType child_end(NodeType *N) { 236 return succ_end(N); 237 } 238}; 239 240template <> struct GraphTraits<const BasicBlock*> { 241 typedef const BasicBlock NodeType; 242 typedef succ_const_iterator ChildIteratorType; 243 244 static NodeType *getEntryNode(const BasicBlock *BB) { return BB; } 245 246 static inline ChildIteratorType child_begin(NodeType *N) { 247 return succ_begin(N); 248 } 249 static inline ChildIteratorType child_end(NodeType *N) { 250 return succ_end(N); 251 } 252}; 253 254// Provide specializations of GraphTraits to be able to treat a function as a 255// graph of basic blocks... and to walk it in inverse order. Inverse order for 256// a function is considered to be when traversing the predecessor edges of a BB 257// instead of the successor edges. 258// 259template <> struct GraphTraits<Inverse<BasicBlock*> > { 260 typedef BasicBlock NodeType; 261 typedef pred_iterator ChildIteratorType; 262 static NodeType *getEntryNode(Inverse<BasicBlock *> G) { return G.Graph; } 263 static inline ChildIteratorType child_begin(NodeType *N) { 264 return pred_begin(N); 265 } 266 static inline ChildIteratorType child_end(NodeType *N) { 267 return pred_end(N); 268 } 269}; 270 271template <> struct GraphTraits<Inverse<const BasicBlock*> > { 272 typedef const BasicBlock NodeType; 273 typedef const_pred_iterator ChildIteratorType; 274 static NodeType *getEntryNode(Inverse<const BasicBlock*> G) { 275 return G.Graph; 276 } 277 static inline ChildIteratorType child_begin(NodeType *N) { 278 return pred_begin(N); 279 } 280 static inline ChildIteratorType child_end(NodeType *N) { 281 return pred_end(N); 282 } 283}; 284 285 286 287//===--------------------------------------------------------------------===// 288// GraphTraits specializations for function basic block graphs (CFGs) 289//===--------------------------------------------------------------------===// 290 291// Provide specializations of GraphTraits to be able to treat a function as a 292// graph of basic blocks... these are the same as the basic block iterators, 293// except that the root node is implicitly the first node of the function. 294// 295template <> struct GraphTraits<Function*> : public GraphTraits<BasicBlock*> { 296 static NodeType *getEntryNode(Function *F) { return &F->getEntryBlock(); } 297 298 // nodes_iterator/begin/end - Allow iteration over all nodes in the graph 299 typedef Function::iterator nodes_iterator; 300 static nodes_iterator nodes_begin(Function *F) { return F->begin(); } 301 static nodes_iterator nodes_end (Function *F) { return F->end(); } 302}; 303template <> struct GraphTraits<const Function*> : 304 public GraphTraits<const BasicBlock*> { 305 static NodeType *getEntryNode(const Function *F) {return &F->getEntryBlock();} 306 307 // nodes_iterator/begin/end - Allow iteration over all nodes in the graph 308 typedef Function::const_iterator nodes_iterator; 309 static nodes_iterator nodes_begin(const Function *F) { return F->begin(); } 310 static nodes_iterator nodes_end (const Function *F) { return F->end(); } 311}; 312 313 314// Provide specializations of GraphTraits to be able to treat a function as a 315// graph of basic blocks... and to walk it in inverse order. Inverse order for 316// a function is considered to be when traversing the predecessor edges of a BB 317// instead of the successor edges. 318// 319template <> struct GraphTraits<Inverse<Function*> > : 320 public GraphTraits<Inverse<BasicBlock*> > { 321 static NodeType *getEntryNode(Inverse<Function*> G) { 322 return &G.Graph->getEntryBlock(); 323 } 324}; 325template <> struct GraphTraits<Inverse<const Function*> > : 326 public GraphTraits<Inverse<const BasicBlock*> > { 327 static NodeType *getEntryNode(Inverse<const Function *> G) { 328 return &G.Graph->getEntryBlock(); 329 } 330}; 331 332} // End llvm namespace 333 334#endif 335