1 //===- CFG.h - Process LLVM structures as graphs ----------------*- C++ -*-===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file defines specializations of GraphTraits that allow Function and
11 // BasicBlock graphs to be treated as proper graphs for generic algorithms.
13 //===----------------------------------------------------------------------===//
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"
33 //===----------------------------------------------------------------------===//
34 // BasicBlock pred_iterator definition
35 //===----------------------------------------------------------------------===//
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*> {
41 std::iterator<std::forward_iterator_tag, Ptr, ptrdiff_t, Ptr*, Ptr*>;
42 using Self = PredIterator<Ptr, USE_iterator>;
45 inline void advancePastNonTerminators() {
46 // Loop to ignore non-terminator uses (for example BlockAddresses).
47 while (!It.atEnd() && !isa<TerminatorInst>(*It))
52 using pointer = typename super::pointer;
53 using reference = typename super::reference;
55 PredIterator() = default;
56 explicit inline PredIterator(Ptr *bb) : It(bb->user_begin()) {
57 advancePastNonTerminators();
59 inline PredIterator(Ptr *bb, bool) : It(bb->user_end()) {}
61 inline bool operator==(const Self& x) const { return It == x.It; }
62 inline bool operator!=(const Self& x) const { return !operator==(x); }
64 inline reference operator*() const {
65 assert(!It.atEnd() && "pred_iterator out of range!");
66 return cast<TerminatorInst>(*It)->getParent();
68 inline pointer *operator->() const { return &operator*(); }
70 inline Self& operator++() { // Preincrement
71 assert(!It.atEnd() && "pred_iterator out of range!");
72 ++It; advancePastNonTerminators();
76 inline Self operator++(int) { // Postincrement
77 Self tmp = *this; ++*this; return tmp;
80 /// getOperandNo - Return the operand number in the predecessor's
81 /// terminator of the successor.
82 unsigned getOperandNo() const {
83 return It.getOperandNo();
86 /// getUse - Return the operand Use in the predecessor's terminator
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>;
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);
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);
107 inline bool pred_empty(const BasicBlock *BB) {
108 return pred_begin(BB) == pred_end(BB);
110 inline pred_range predecessors(BasicBlock *BB) {
111 return pred_range(pred_begin(BB), pred_end(BB));
113 inline pred_const_range predecessors(const BasicBlock *BB) {
114 return pred_const_range(pred_begin(BB), pred_end(BB));
117 //===----------------------------------------------------------------------===//
118 // BasicBlock succ_iterator helpers
119 //===----------------------------------------------------------------------===//
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>;
128 inline succ_iterator succ_begin(BasicBlock *BB) {
129 return succ_iterator(BB->getTerminator());
131 inline succ_const_iterator succ_begin(const BasicBlock *BB) {
132 return succ_const_iterator(BB->getTerminator());
134 inline succ_iterator succ_end(BasicBlock *BB) {
135 return succ_iterator(BB->getTerminator(), true);
137 inline succ_const_iterator succ_end(const BasicBlock *BB) {
138 return succ_const_iterator(BB->getTerminator(), true);
140 inline bool succ_empty(const BasicBlock *BB) {
141 return succ_begin(BB) == succ_end(BB);
143 inline succ_range successors(BasicBlock *BB) {
144 return succ_range(succ_begin(BB), succ_end(BB));
146 inline succ_const_range successors(const BasicBlock *BB) {
147 return succ_const_range(succ_begin(BB), succ_end(BB));
150 template <typename T, typename U>
151 struct isPodLike<TerminatorInst::SuccIterator<T, U>> {
152 static const bool value = isPodLike<T>::value;
155 //===--------------------------------------------------------------------===//
156 // GraphTraits specializations for basic block graphs (CFGs)
157 //===--------------------------------------------------------------------===//
159 // Provide specializations of GraphTraits to be able to treat a function as a
160 // graph of basic blocks...
162 template <> struct GraphTraits<BasicBlock*> {
163 using NodeRef = BasicBlock *;
164 using ChildIteratorType = succ_iterator;
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); }
171 template <> struct GraphTraits<const BasicBlock*> {
172 using NodeRef = const BasicBlock *;
173 using ChildIteratorType = succ_const_iterator;
175 static NodeRef getEntryNode(const BasicBlock *BB) { return BB; }
177 static ChildIteratorType child_begin(NodeRef N) { return succ_begin(N); }
178 static ChildIteratorType child_end(NodeRef N) { return succ_end(N); }
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.
186 template <> struct GraphTraits<Inverse<BasicBlock*>> {
187 using NodeRef = BasicBlock *;
188 using ChildIteratorType = pred_iterator;
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); }
195 template <> struct GraphTraits<Inverse<const BasicBlock*>> {
196 using NodeRef = const BasicBlock *;
197 using ChildIteratorType = const_pred_iterator;
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); }
204 //===--------------------------------------------------------------------===//
205 // GraphTraits specializations for function basic block graphs (CFGs)
206 //===--------------------------------------------------------------------===//
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.
212 template <> struct GraphTraits<Function*> : public GraphTraits<BasicBlock*> {
213 static NodeRef getEntryNode(Function *F) { return &F->getEntryBlock(); }
215 // nodes_iterator/begin/end - Allow iteration over all nodes in the graph
216 using nodes_iterator = pointer_iterator<Function::iterator>;
218 static nodes_iterator nodes_begin(Function *F) {
219 return nodes_iterator(F->begin());
222 static nodes_iterator nodes_end(Function *F) {
223 return nodes_iterator(F->end());
226 static size_t size(Function *F) { return F->size(); }
228 template <> struct GraphTraits<const Function*> :
229 public GraphTraits<const BasicBlock*> {
230 static NodeRef getEntryNode(const Function *F) { return &F->getEntryBlock(); }
232 // nodes_iterator/begin/end - Allow iteration over all nodes in the graph
233 using nodes_iterator = pointer_iterator<Function::const_iterator>;
235 static nodes_iterator nodes_begin(const Function *F) {
236 return nodes_iterator(F->begin());
239 static nodes_iterator nodes_end(const Function *F) {
240 return nodes_iterator(F->end());
243 static size_t size(const Function *F) { return F->size(); }
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.
251 template <> struct GraphTraits<Inverse<Function*>> :
252 public GraphTraits<Inverse<BasicBlock*>> {
253 static NodeRef getEntryNode(Inverse<Function *> G) {
254 return &G.Graph->getEntryBlock();
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();
264 } // end namespace llvm
266 #endif // LLVM_IR_CFG_H