1 //===- 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_IR_CFG_H 16 #define LLVM_IR_CFG_H 17 18 #include "llvm/ADT/GraphTraits.h" 19 #include "llvm/ADT/iterator.h" 20 #include "llvm/ADT/iterator_range.h" 21 #include "llvm/IR/BasicBlock.h" 22 #include "llvm/IR/Function.h" 23 #include "llvm/IR/InstrTypes.h" 24 #include "llvm/IR/Value.h" 25 #include "llvm/Support/Casting.h" 26 #include "llvm/Support/type_traits.h" 27 #include <cassert> 28 #include <cstddef> 29 #include <iterator> 30 31 namespace llvm { 32 33 //===----------------------------------------------------------------------===// 34 // BasicBlock pred_iterator definition 35 //===----------------------------------------------------------------------===// 36 37 template <class Ptr, class USE_iterator> // Predecessor Iterator 38 class PredIterator : public std::iterator<std::forward_iterator_tag, 39 Ptr, ptrdiff_t, Ptr*, Ptr*> { 40 using super = 41 std::iterator<std::forward_iterator_tag, Ptr, ptrdiff_t, Ptr*, Ptr*>; 42 using Self = PredIterator<Ptr, USE_iterator>; 43 USE_iterator It; 44 45 inline void advancePastNonTerminators() { 46 // Loop to ignore non-terminator uses (for example BlockAddresses). 47 while (!It.atEnd() && !isa<TerminatorInst>(*It)) 48 ++It; 49 } 50 51 public: 52 using pointer = typename super::pointer; 53 using reference = typename super::reference; 54 55 PredIterator() = default; 56 explicit inline PredIterator(Ptr *bb) : It(bb->user_begin()) { 57 advancePastNonTerminators(); 58 } 59 inline PredIterator(Ptr *bb, bool) : It(bb->user_end()) {} 60 61 inline bool operator==(const Self& x) const { return It == x.It; } 62 inline bool operator!=(const Self& x) const { return !operator==(x); } 63 64 inline reference operator*() const { 65 assert(!It.atEnd() && "pred_iterator out of range!"); 66 return cast<TerminatorInst>(*It)->getParent(); 67 } 68 inline pointer *operator->() const { return &operator*(); } 69 70 inline Self& operator++() { // Preincrement 71 assert(!It.atEnd() && "pred_iterator out of range!"); 72 ++It; advancePastNonTerminators(); 73 return *this; 74 } 75 76 inline Self operator++(int) { // Postincrement 77 Self tmp = *this; ++*this; return tmp; 78 } 79 80 /// getOperandNo - Return the operand number in the predecessor's 81 /// terminator of the successor. 82 unsigned getOperandNo() const { 83 return It.getOperandNo(); 84 } 85 86 /// getUse - Return the operand Use in the predecessor's terminator 87 /// of the successor. 88 Use &getUse() const { 89 return It.getUse(); 90 } 91 }; 92 93 using pred_iterator = PredIterator<BasicBlock, Value::user_iterator>; 94 using const_pred_iterator = 95 PredIterator<const BasicBlock, Value::const_user_iterator>; 96 using pred_range = iterator_range<pred_iterator>; 97 using pred_const_range = iterator_range<const_pred_iterator>; 98 99 inline pred_iterator pred_begin(BasicBlock *BB) { return pred_iterator(BB); } 100 inline const_pred_iterator pred_begin(const BasicBlock *BB) { 101 return const_pred_iterator(BB); 102 } 103 inline pred_iterator pred_end(BasicBlock *BB) { return pred_iterator(BB, true);} 104 inline const_pred_iterator pred_end(const BasicBlock *BB) { 105 return const_pred_iterator(BB, true); 106 } 107 inline bool pred_empty(const BasicBlock *BB) { 108 return pred_begin(BB) == pred_end(BB); 109 } 110 inline pred_range predecessors(BasicBlock *BB) { 111 return pred_range(pred_begin(BB), pred_end(BB)); 112 } 113 inline pred_const_range predecessors(const BasicBlock *BB) { 114 return pred_const_range(pred_begin(BB), pred_end(BB)); 115 } 116 117 //===----------------------------------------------------------------------===// 118 // BasicBlock succ_iterator helpers 119 //===----------------------------------------------------------------------===// 120 121 using succ_iterator = 122 TerminatorInst::SuccIterator<TerminatorInst *, BasicBlock>; 123 using succ_const_iterator = 124 TerminatorInst::SuccIterator<const TerminatorInst *, const BasicBlock>; 125 using succ_range = iterator_range<succ_iterator>; 126 using succ_const_range = iterator_range<succ_const_iterator>; 127 128 inline succ_iterator succ_begin(BasicBlock *BB) { 129 return succ_iterator(BB->getTerminator()); 130 } 131 inline succ_const_iterator succ_begin(const BasicBlock *BB) { 132 return succ_const_iterator(BB->getTerminator()); 133 } 134 inline succ_iterator succ_end(BasicBlock *BB) { 135 return succ_iterator(BB->getTerminator(), true); 136 } 137 inline succ_const_iterator succ_end(const BasicBlock *BB) { 138 return succ_const_iterator(BB->getTerminator(), true); 139 } 140 inline bool succ_empty(const BasicBlock *BB) { 141 return succ_begin(BB) == succ_end(BB); 142 } 143 inline succ_range successors(BasicBlock *BB) { 144 return succ_range(succ_begin(BB), succ_end(BB)); 145 } 146 inline succ_const_range successors(const BasicBlock *BB) { 147 return succ_const_range(succ_begin(BB), succ_end(BB)); 148 } 149 150 template <typename T, typename U> 151 struct isPodLike<TerminatorInst::SuccIterator<T, U>> { 152 static const bool value = isPodLike<T>::value; 153 }; 154 155 //===--------------------------------------------------------------------===// 156 // GraphTraits specializations for basic block graphs (CFGs) 157 //===--------------------------------------------------------------------===// 158 159 // Provide specializations of GraphTraits to be able to treat a function as a 160 // graph of basic blocks... 161 162 template <> struct GraphTraits<BasicBlock*> { 163 using NodeRef = BasicBlock *; 164 using ChildIteratorType = succ_iterator; 165 166 static NodeRef getEntryNode(BasicBlock *BB) { return BB; } 167 static ChildIteratorType child_begin(NodeRef N) { return succ_begin(N); } 168 static ChildIteratorType child_end(NodeRef N) { return succ_end(N); } 169 }; 170 171 template <> struct GraphTraits<const BasicBlock*> { 172 using NodeRef = const BasicBlock *; 173 using ChildIteratorType = succ_const_iterator; 174 175 static NodeRef getEntryNode(const BasicBlock *BB) { return BB; } 176 177 static ChildIteratorType child_begin(NodeRef N) { return succ_begin(N); } 178 static ChildIteratorType child_end(NodeRef N) { return succ_end(N); } 179 }; 180 181 // Provide specializations of GraphTraits to be able to treat a function as a 182 // graph of basic blocks... and to walk it in inverse order. Inverse order for 183 // a function is considered to be when traversing the predecessor edges of a BB 184 // instead of the successor edges. 185 // 186 template <> struct GraphTraits<Inverse<BasicBlock*>> { 187 using NodeRef = BasicBlock *; 188 using ChildIteratorType = pred_iterator; 189 190 static NodeRef getEntryNode(Inverse<BasicBlock *> G) { return G.Graph; } 191 static ChildIteratorType child_begin(NodeRef N) { return pred_begin(N); } 192 static ChildIteratorType child_end(NodeRef N) { return pred_end(N); } 193 }; 194 195 template <> struct GraphTraits<Inverse<const BasicBlock*>> { 196 using NodeRef = const BasicBlock *; 197 using ChildIteratorType = const_pred_iterator; 198 199 static NodeRef getEntryNode(Inverse<const BasicBlock *> G) { return G.Graph; } 200 static ChildIteratorType child_begin(NodeRef N) { return pred_begin(N); } 201 static ChildIteratorType child_end(NodeRef N) { return pred_end(N); } 202 }; 203 204 //===--------------------------------------------------------------------===// 205 // GraphTraits specializations for function basic block graphs (CFGs) 206 //===--------------------------------------------------------------------===// 207 208 // Provide specializations of GraphTraits to be able to treat a function as a 209 // graph of basic blocks... these are the same as the basic block iterators, 210 // except that the root node is implicitly the first node of the function. 211 // 212 template <> struct GraphTraits<Function*> : public GraphTraits<BasicBlock*> { 213 static NodeRef getEntryNode(Function *F) { return &F->getEntryBlock(); } 214 215 // nodes_iterator/begin/end - Allow iteration over all nodes in the graph 216 using nodes_iterator = pointer_iterator<Function::iterator>; 217 218 static nodes_iterator nodes_begin(Function *F) { 219 return nodes_iterator(F->begin()); 220 } 221 222 static nodes_iterator nodes_end(Function *F) { 223 return nodes_iterator(F->end()); 224 } 225 226 static size_t size(Function *F) { return F->size(); } 227 }; 228 template <> struct GraphTraits<const Function*> : 229 public GraphTraits<const BasicBlock*> { 230 static NodeRef getEntryNode(const Function *F) { return &F->getEntryBlock(); } 231 232 // nodes_iterator/begin/end - Allow iteration over all nodes in the graph 233 using nodes_iterator = pointer_iterator<Function::const_iterator>; 234 235 static nodes_iterator nodes_begin(const Function *F) { 236 return nodes_iterator(F->begin()); 237 } 238 239 static nodes_iterator nodes_end(const Function *F) { 240 return nodes_iterator(F->end()); 241 } 242 243 static size_t size(const Function *F) { return F->size(); } 244 }; 245 246 // Provide specializations of GraphTraits to be able to treat a function as a 247 // graph of basic blocks... and to walk it in inverse order. Inverse order for 248 // a function is considered to be when traversing the predecessor edges of a BB 249 // instead of the successor edges. 250 // 251 template <> struct GraphTraits<Inverse<Function*>> : 252 public GraphTraits<Inverse<BasicBlock*>> { 253 static NodeRef getEntryNode(Inverse<Function *> G) { 254 return &G.Graph->getEntryBlock(); 255 } 256 }; 257 template <> struct GraphTraits<Inverse<const Function*>> : 258 public GraphTraits<Inverse<const BasicBlock*>> { 259 static NodeRef getEntryNode(Inverse<const Function *> G) { 260 return &G.Graph->getEntryBlock(); 261 } 262 }; 263 264 } // end namespace llvm 265 266 #endif // LLVM_IR_CFG_H 267
