CFG.h revision 5106140a50c28536dca1cbf02ade8de988cad537 
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  _USE_iterator It;
33public:
34  typedef PredIterator<_Ptr,_USE_iterator> _Self;
35  typedef typename super::pointer pointer;
36
37  inline void advancePastNonTerminators() {
38    // Loop to ignore non terminator uses (for example PHI nodes)...
39    while (!It.atEnd() && !isa<TerminatorInst>(*It))
40      ++It;
41  }
42
43  inline PredIterator(_Ptr *bb) : It(bb->use_begin()) {
44    advancePastNonTerminators();
45  }
46  inline PredIterator(_Ptr *bb, bool) : It(bb->use_end()) {}
47
48  inline bool operator==(const _Self& x) const { return It == x.It; }
49  inline bool operator!=(const _Self& x) const { return !operator==(x); }
50
51  inline pointer operator*() const {
52    assert(!It.atEnd() && "pred_iterator out of range!");
53    return cast<TerminatorInst>(*It)->getParent();
54  }
55  inline pointer *operator->() const { return &(operator*()); }
56
57  inline _Self& operator++() {   // Preincrement
58    assert(!It.atEnd() && "pred_iterator out of range!");
59    ++It; advancePastNonTerminators();
60    return *this;
61  }
62
63  inline _Self operator++(int) { // Postincrement
64    _Self tmp = *this; ++*this; return tmp;
65  }
66};
67
68typedef PredIterator<BasicBlock, Value::use_iterator> pred_iterator;
69typedef PredIterator<const BasicBlock,
70                     Value::use_const_iterator> pred_const_iterator;
71
72inline pred_iterator pred_begin(BasicBlock *BB) { return pred_iterator(BB); }
73inline pred_const_iterator pred_begin(const BasicBlock *BB) {
74  return pred_const_iterator(BB);
75}
76inline pred_iterator pred_end(BasicBlock *BB) { return pred_iterator(BB, true);}
77inline pred_const_iterator pred_end(const BasicBlock *BB) {
78  return pred_const_iterator(BB, true);
79}
80
81
82
83//===----------------------------------------------------------------------===//
84// BasicBlock succ_iterator definition
85//===----------------------------------------------------------------------===//
86
87template <class Term_, class BB_>           // Successor Iterator
88class SuccIterator : public std::iterator<std::bidirectional_iterator_tag,
89                                          BB_, ptrdiff_t> {
90  const Term_ Term;
91  unsigned idx;
92  typedef std::iterator<std::bidirectional_iterator_tag, BB_, ptrdiff_t> super;
93public:
94  typedef SuccIterator<Term_, BB_> _Self;
95  typedef typename super::pointer pointer;
96  // TODO: This can be random access iterator, only operator[] missing.
97
98  inline SuccIterator(Term_ T) : Term(T), idx(0) {         // begin iterator
99    assert(T && "getTerminator returned null!");
100  }
101  inline SuccIterator(Term_ T, bool)                       // end iterator
102    : Term(T), idx(Term->getNumSuccessors()) {
103    assert(T && "getTerminator returned null!");
104  }
105
106  inline const _Self &operator=(const _Self &I) {
107    assert(Term == I.Term &&"Cannot assign iterators to two different blocks!");
108    idx = I.idx;
109    return *this;
110  }
111
112  inline bool index_is_valid (int idx) {
113    return idx >= 0 && (unsigned) idx < Term->getNumSuccessors();
114  }
115
116  /// getSuccessorIndex - This is used to interface between code that wants to
117  /// operate on terminator instructions directly.
118  unsigned getSuccessorIndex() const { return idx; }
119
120  inline bool operator==(const _Self& x) const { return idx == x.idx; }
121  inline bool operator!=(const _Self& x) const { return !operator==(x); }
122
123  inline pointer operator*() const { return Term->getSuccessor(idx); }
124  inline pointer operator->() const { return operator*(); }
125
126  inline _Self& operator++() { ++idx; return *this; } // Preincrement
127
128  inline _Self operator++(int) { // Postincrement
129    _Self tmp = *this; ++*this; return tmp;
130  }
131
132  inline _Self& operator--() { --idx; return *this; }  // Predecrement
133  inline _Self operator--(int) { // Postdecrement
134    _Self tmp = *this; --*this; return tmp;
135  }
136
137  inline bool operator<(const _Self& x) const {
138    assert(Term == x.Term && "Cannot compare iterators of different blocks!");
139    return idx < x.idx;
140  }
141
142  inline bool operator<=(const _Self& x) const {
143    assert(Term == x.Term && "Cannot compare iterators of different blocks!");
144    return idx <= x.idx;
145  }
146  inline bool operator>=(const _Self& x) const {
147    assert(Term == x.Term && "Cannot compare iterators of different blocks!");
148    return idx >= x.idx;
149  }
150
151  inline bool operator>(const _Self& x) const {
152    return idx > x.idx;
153    assert(Term == x.Term && "Cannot compare iterators of different blocks!");
154  }
155
156  inline _Self& operator+=(int Right) {
157    unsigned new_idx = idx + Right;
158    assert(index_is_valid(new_idx) && "Iterator index out of bound");
159    idx = new_idx;
160    return *this;
161  }
162
163  inline _Self operator+(int Right) {
164    _Self tmp = *this;
165    tmp += Right;
166    return tmp;
167  }
168
169  inline _Self& operator-=(int Right) {
170    return operator+=(-Right);
171  }
172
173  inline _Self operator-(int Right) {
174    return operator+(-Right);
175  }
176
177  inline int operator-(const _Self& x) {
178    assert(Term == x.Term && "Cannot work on iterators of different blocks!");
179    int distance = idx - x.idx;
180    return distance;
181  }
182
183  // This works for read access, however write access is difficult as changes
184  // to Term are only possible with Term->setSuccessor(idx). Pointers that can
185  // be modified are not available.
186  //
187  // inline pointer operator[](int offset) {
188  //  _Self tmp = *this;
189  //  tmp += offset;
190  //  return tmp.operator*();
191  // }
192};
193
194typedef SuccIterator<TerminatorInst*, BasicBlock> succ_iterator;
195typedef SuccIterator<const TerminatorInst*,
196                     const BasicBlock> succ_const_iterator;
197
198inline succ_iterator succ_begin(BasicBlock *BB) {
199  return succ_iterator(BB->getTerminator());
200}
201inline succ_const_iterator succ_begin(const BasicBlock *BB) {
202  return succ_const_iterator(BB->getTerminator());
203}
204inline succ_iterator succ_end(BasicBlock *BB) {
205  return succ_iterator(BB->getTerminator(), true);
206}
207inline succ_const_iterator succ_end(const BasicBlock *BB) {
208  return succ_const_iterator(BB->getTerminator(), true);
209}
210
211
212
213//===--------------------------------------------------------------------===//
214// GraphTraits specializations for basic block graphs (CFGs)
215//===--------------------------------------------------------------------===//
216
217// Provide specializations of GraphTraits to be able to treat a function as a
218// graph of basic blocks...
219
220template <> struct GraphTraits<BasicBlock*> {
221  typedef BasicBlock NodeType;
222  typedef succ_iterator ChildIteratorType;
223
224  static NodeType *getEntryNode(BasicBlock *BB) { return BB; }
225  static inline ChildIteratorType child_begin(NodeType *N) {
226    return succ_begin(N);
227  }
228  static inline ChildIteratorType child_end(NodeType *N) {
229    return succ_end(N);
230  }
231};
232
233template <> struct GraphTraits<const BasicBlock*> {
234  typedef const BasicBlock NodeType;
235  typedef succ_const_iterator ChildIteratorType;
236
237  static NodeType *getEntryNode(const BasicBlock *BB) { return BB; }
238
239  static inline ChildIteratorType child_begin(NodeType *N) {
240    return succ_begin(N);
241  }
242  static inline ChildIteratorType child_end(NodeType *N) {
243    return succ_end(N);
244  }
245};
246
247// Provide specializations of GraphTraits to be able to treat a function as a
248// graph of basic blocks... and to walk it in inverse order.  Inverse order for
249// a function is considered to be when traversing the predecessor edges of a BB
250// instead of the successor edges.
251//
252template <> struct GraphTraits<Inverse<BasicBlock*> > {
253  typedef BasicBlock NodeType;
254  typedef pred_iterator ChildIteratorType;
255  static NodeType *getEntryNode(Inverse<BasicBlock *> G) { return G.Graph; }
256  static inline ChildIteratorType child_begin(NodeType *N) {
257    return pred_begin(N);
258  }
259  static inline ChildIteratorType child_end(NodeType *N) {
260    return pred_end(N);
261  }
262};
263
264template <> struct GraphTraits<Inverse<const BasicBlock*> > {
265  typedef const BasicBlock NodeType;
266  typedef pred_const_iterator ChildIteratorType;
267  static NodeType *getEntryNode(Inverse<const BasicBlock*> G) {
268    return G.Graph;
269  }
270  static inline ChildIteratorType child_begin(NodeType *N) {
271    return pred_begin(N);
272  }
273  static inline ChildIteratorType child_end(NodeType *N) {
274    return pred_end(N);
275  }
276};
277
278
279
280//===--------------------------------------------------------------------===//
281// GraphTraits specializations for function basic block graphs (CFGs)
282//===--------------------------------------------------------------------===//
283
284// Provide specializations of GraphTraits to be able to treat a function as a
285// graph of basic blocks... these are the same as the basic block iterators,
286// except that the root node is implicitly the first node of the function.
287//
288template <> struct GraphTraits<Function*> : public GraphTraits<BasicBlock*> {
289  static NodeType *getEntryNode(Function *F) { return &F->getEntryBlock(); }
290
291  // nodes_iterator/begin/end - Allow iteration over all nodes in the graph
292  typedef Function::iterator nodes_iterator;
293  static nodes_iterator nodes_begin(Function *F) { return F->begin(); }
294  static nodes_iterator nodes_end  (Function *F) { return F->end(); }
295};
296template <> struct GraphTraits<const Function*> :
297  public GraphTraits<const BasicBlock*> {
298  static NodeType *getEntryNode(const Function *F) {return &F->getEntryBlock();}
299
300  // nodes_iterator/begin/end - Allow iteration over all nodes in the graph
301  typedef Function::const_iterator nodes_iterator;
302  static nodes_iterator nodes_begin(const Function *F) { return F->begin(); }
303  static nodes_iterator nodes_end  (const Function *F) { return F->end(); }
304};
305
306
307// Provide specializations of GraphTraits to be able to treat a function as a
308// graph of basic blocks... and to walk it in inverse order.  Inverse order for
309// a function is considered to be when traversing the predecessor edges of a BB
310// instead of the successor edges.
311//
312template <> struct GraphTraits<Inverse<Function*> > :
313  public GraphTraits<Inverse<BasicBlock*> > {
314  static NodeType *getEntryNode(Inverse<Function*> G) {
315    return &G.Graph->getEntryBlock();
316  }
317};
318template <> struct GraphTraits<Inverse<const Function*> > :
319  public GraphTraits<Inverse<const BasicBlock*> > {
320  static NodeType *getEntryNode(Inverse<const Function *> G) {
321    return &G.Graph->getEntryBlock();
322  }
323};
324
325} // End llvm namespace
326
327#endif
328