1 //===-- llvm/Support/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 //===----------------------------------------------------------------------===//
15 #ifndef LLVM_SUPPORT_CFG_H
16 #define LLVM_SUPPORT_CFG_H
18 #include "llvm/ADT/GraphTraits.h"
19 #include "llvm/Function.h"
20 #include "llvm/InstrTypes.h"
24 //===----------------------------------------------------------------------===//
25 // BasicBlock pred_iterator definition
26 //===----------------------------------------------------------------------===//
28 template <class Ptr, class USE_iterator> // Predecessor Iterator
29 class PredIterator : public std::iterator<std::forward_iterator_tag,
31 typedef std::iterator<std::forward_iterator_tag, Ptr, ptrdiff_t> super;
32 typedef PredIterator<Ptr, USE_iterator> Self;
35 inline void advancePastNonTerminators() {
36 // Loop to ignore non terminator uses (for example BlockAddresses).
37 while (!It.atEnd() && !isa<TerminatorInst>(*It))
42 typedef typename super::pointer pointer;
45 explicit inline PredIterator(Ptr *bb) : It(bb->use_begin()) {
46 advancePastNonTerminators();
48 inline PredIterator(Ptr *bb, bool) : It(bb->use_end()) {}
50 inline bool operator==(const Self& x) const { return It == x.It; }
51 inline bool operator!=(const Self& x) const { return !operator==(x); }
53 inline pointer operator*() const {
54 assert(!It.atEnd() && "pred_iterator out of range!");
55 return cast<TerminatorInst>(*It)->getParent();
57 inline pointer *operator->() const { return &operator*(); }
59 inline Self& operator++() { // Preincrement
60 assert(!It.atEnd() && "pred_iterator out of range!");
61 ++It; advancePastNonTerminators();
65 inline Self operator++(int) { // Postincrement
66 Self tmp = *this; ++*this; return tmp;
69 /// getOperandNo - Return the operand number in the predecessor's
70 /// terminator of the successor.
71 unsigned getOperandNo() const {
72 return It.getOperandNo();
76 typedef PredIterator<BasicBlock, Value::use_iterator> pred_iterator;
77 typedef PredIterator<const BasicBlock,
78 Value::const_use_iterator> const_pred_iterator;
80 inline pred_iterator pred_begin(BasicBlock *BB) { return pred_iterator(BB); }
81 inline const_pred_iterator pred_begin(const BasicBlock *BB) {
82 return const_pred_iterator(BB);
84 inline pred_iterator pred_end(BasicBlock *BB) { return pred_iterator(BB, true);}
85 inline const_pred_iterator pred_end(const BasicBlock *BB) {
86 return const_pred_iterator(BB, true);
91 //===----------------------------------------------------------------------===//
92 // BasicBlock succ_iterator definition
93 //===----------------------------------------------------------------------===//
95 template <class Term_, class BB_> // Successor Iterator
96 class SuccIterator : public std::iterator<std::bidirectional_iterator_tag,
100 typedef std::iterator<std::bidirectional_iterator_tag, BB_, ptrdiff_t> super;
101 typedef SuccIterator<Term_, BB_> Self;
103 inline bool index_is_valid(int idx) {
104 return idx >= 0 && (unsigned) idx < Term->getNumSuccessors();
108 typedef typename super::pointer pointer;
109 // TODO: This can be random access iterator, only operator[] missing.
111 explicit inline SuccIterator(Term_ T) : Term(T), idx(0) {// begin iterator
113 inline SuccIterator(Term_ T, bool) // end iterator
116 idx = Term->getNumSuccessors();
118 // Term == NULL happens, if a basic block is not fully constructed and
119 // consequently getTerminator() returns NULL. In this case we construct a
120 // SuccIterator which describes a basic block that has zero successors.
121 // Defining SuccIterator for incomplete and malformed CFGs is especially
122 // useful for debugging.
126 inline const Self &operator=(const Self &I) {
127 assert(Term == I.Term &&"Cannot assign iterators to two different blocks!");
132 /// getSuccessorIndex - This is used to interface between code that wants to
133 /// operate on terminator instructions directly.
134 unsigned getSuccessorIndex() const { return idx; }
136 inline bool operator==(const Self& x) const { return idx == x.idx; }
137 inline bool operator!=(const Self& x) const { return !operator==(x); }
139 inline pointer operator*() const { return Term->getSuccessor(idx); }
140 inline pointer operator->() const { return operator*(); }
142 inline Self& operator++() { ++idx; return *this; } // Preincrement
144 inline Self operator++(int) { // Postincrement
145 Self tmp = *this; ++*this; return tmp;
148 inline Self& operator--() { --idx; return *this; } // Predecrement
149 inline Self operator--(int) { // Postdecrement
150 Self tmp = *this; --*this; return tmp;
153 inline bool operator<(const Self& x) const {
154 assert(Term == x.Term && "Cannot compare iterators of different blocks!");
158 inline bool operator<=(const Self& x) const {
159 assert(Term == x.Term && "Cannot compare iterators of different blocks!");
162 inline bool operator>=(const Self& x) const {
163 assert(Term == x.Term && "Cannot compare iterators of different blocks!");
167 inline bool operator>(const Self& x) const {
168 assert(Term == x.Term && "Cannot compare iterators of different blocks!");
172 inline Self& operator+=(int Right) {
173 unsigned new_idx = idx + Right;
174 assert(index_is_valid(new_idx) && "Iterator index out of bound");
179 inline Self operator+(int Right) {
185 inline Self& operator-=(int Right) {
186 return operator+=(-Right);
189 inline Self operator-(int Right) {
190 return operator+(-Right);
193 inline int operator-(const Self& x) {
194 assert(Term == x.Term && "Cannot work on iterators of different blocks!");
195 int distance = idx - x.idx;
199 // This works for read access, however write access is difficult as changes
200 // to Term are only possible with Term->setSuccessor(idx). Pointers that can
201 // be modified are not available.
203 // inline pointer operator[](int offset) {
206 // return tmp.operator*();
209 /// Get the source BB of this iterator.
210 inline BB_ *getSource() {
211 assert(Term && "Source not available, if basic block was malformed");
212 return Term->getParent();
216 typedef SuccIterator<TerminatorInst*, BasicBlock> succ_iterator;
217 typedef SuccIterator<const TerminatorInst*,
218 const BasicBlock> succ_const_iterator;
220 inline succ_iterator succ_begin(BasicBlock *BB) {
221 return succ_iterator(BB->getTerminator());
223 inline succ_const_iterator succ_begin(const BasicBlock *BB) {
224 return succ_const_iterator(BB->getTerminator());
226 inline succ_iterator succ_end(BasicBlock *BB) {
227 return succ_iterator(BB->getTerminator(), true);
229 inline succ_const_iterator succ_end(const BasicBlock *BB) {
230 return succ_const_iterator(BB->getTerminator(), true);
235 //===--------------------------------------------------------------------===//
236 // GraphTraits specializations for basic block graphs (CFGs)
237 //===--------------------------------------------------------------------===//
239 // Provide specializations of GraphTraits to be able to treat a function as a
240 // graph of basic blocks...
242 template <> struct GraphTraits<BasicBlock*> {
243 typedef BasicBlock NodeType;
244 typedef succ_iterator ChildIteratorType;
246 static NodeType *getEntryNode(BasicBlock *BB) { return BB; }
247 static inline ChildIteratorType child_begin(NodeType *N) {
248 return succ_begin(N);
250 static inline ChildIteratorType child_end(NodeType *N) {
255 template <> struct GraphTraits<const BasicBlock*> {
256 typedef const BasicBlock NodeType;
257 typedef succ_const_iterator ChildIteratorType;
259 static NodeType *getEntryNode(const BasicBlock *BB) { return BB; }
261 static inline ChildIteratorType child_begin(NodeType *N) {
262 return succ_begin(N);
264 static inline ChildIteratorType child_end(NodeType *N) {
269 // Provide specializations of GraphTraits to be able to treat a function as a
270 // graph of basic blocks... and to walk it in inverse order. Inverse order for
271 // a function is considered to be when traversing the predecessor edges of a BB
272 // instead of the successor edges.
274 template <> struct GraphTraits<Inverse<BasicBlock*> > {
275 typedef BasicBlock NodeType;
276 typedef pred_iterator ChildIteratorType;
277 static NodeType *getEntryNode(Inverse<BasicBlock *> G) { return G.Graph; }
278 static inline ChildIteratorType child_begin(NodeType *N) {
279 return pred_begin(N);
281 static inline ChildIteratorType child_end(NodeType *N) {
286 template <> struct GraphTraits<Inverse<const BasicBlock*> > {
287 typedef const BasicBlock NodeType;
288 typedef const_pred_iterator ChildIteratorType;
289 static NodeType *getEntryNode(Inverse<const BasicBlock*> G) {
292 static inline ChildIteratorType child_begin(NodeType *N) {
293 return pred_begin(N);
295 static inline ChildIteratorType child_end(NodeType *N) {
302 //===--------------------------------------------------------------------===//
303 // GraphTraits specializations for function basic block graphs (CFGs)
304 //===--------------------------------------------------------------------===//
306 // Provide specializations of GraphTraits to be able to treat a function as a
307 // graph of basic blocks... these are the same as the basic block iterators,
308 // except that the root node is implicitly the first node of the function.
310 template <> struct GraphTraits<Function*> : public GraphTraits<BasicBlock*> {
311 static NodeType *getEntryNode(Function *F) { return &F->getEntryBlock(); }
313 // nodes_iterator/begin/end - Allow iteration over all nodes in the graph
314 typedef Function::iterator nodes_iterator;
315 static nodes_iterator nodes_begin(Function *F) { return F->begin(); }
316 static nodes_iterator nodes_end (Function *F) { return F->end(); }
317 static unsigned size (Function *F) { return F->size(); }
319 template <> struct GraphTraits<const Function*> :
320 public GraphTraits<const BasicBlock*> {
321 static NodeType *getEntryNode(const Function *F) {return &F->getEntryBlock();}
323 // nodes_iterator/begin/end - Allow iteration over all nodes in the graph
324 typedef Function::const_iterator nodes_iterator;
325 static nodes_iterator nodes_begin(const Function *F) { return F->begin(); }
326 static nodes_iterator nodes_end (const Function *F) { return F->end(); }
327 static unsigned size (const Function *F) { return F->size(); }
331 // Provide specializations of GraphTraits to be able to treat a function as a
332 // graph of basic blocks... and to walk it in inverse order. Inverse order for
333 // a function is considered to be when traversing the predecessor edges of a BB
334 // instead of the successor edges.
336 template <> struct GraphTraits<Inverse<Function*> > :
337 public GraphTraits<Inverse<BasicBlock*> > {
338 static NodeType *getEntryNode(Inverse<Function*> G) {
339 return &G.Graph->getEntryBlock();
342 template <> struct GraphTraits<Inverse<const Function*> > :
343 public GraphTraits<Inverse<const BasicBlock*> > {
344 static NodeType *getEntryNode(Inverse<const Function *> G) {
345 return &G.Graph->getEntryBlock();
349 } // End llvm namespace