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_range.h"
20#include "llvm/IR/Function.h"
21#include "llvm/IR/InstrTypes.h"
22
23namespace llvm {
24
25//===----------------------------------------------------------------------===//
26// BasicBlock pred_iterator definition
27//===----------------------------------------------------------------------===//
28
29template <class Ptr, class USE_iterator> // Predecessor Iterator
30class PredIterator : public std::iterator<std::forward_iterator_tag,
31                                          Ptr, ptrdiff_t, Ptr*, Ptr*> {
32  typedef std::iterator<std::forward_iterator_tag, Ptr, ptrdiff_t, Ptr*,
33                                                                    Ptr*> super;
34  typedef PredIterator<Ptr, USE_iterator> Self;
35  USE_iterator It;
36
37  inline void advancePastNonTerminators() {
38    // Loop to ignore non-terminator uses (for example BlockAddresses).
39    while (!It.atEnd() && !isa<TerminatorInst>(*It))
40      ++It;
41  }
42
43public:
44  typedef typename super::pointer pointer;
45  typedef typename super::reference reference;
46
47  PredIterator() {}
48  explicit inline PredIterator(Ptr *bb) : It(bb->user_begin()) {
49    advancePastNonTerminators();
50  }
51  inline PredIterator(Ptr *bb, bool) : It(bb->user_end()) {}
52
53  inline bool operator==(const Self& x) const { return It == x.It; }
54  inline bool operator!=(const Self& x) const { return !operator==(x); }
55
56  inline reference operator*() const {
57    assert(!It.atEnd() && "pred_iterator out of range!");
58    return cast<TerminatorInst>(*It)->getParent();
59  }
60  inline pointer *operator->() const { return &operator*(); }
61
62  inline Self& operator++() {   // Preincrement
63    assert(!It.atEnd() && "pred_iterator out of range!");
64    ++It; advancePastNonTerminators();
65    return *this;
66  }
67
68  inline Self operator++(int) { // Postincrement
69    Self tmp = *this; ++*this; return tmp;
70  }
71
72  /// getOperandNo - Return the operand number in the predecessor's
73  /// terminator of the successor.
74  unsigned getOperandNo() const {
75    return It.getOperandNo();
76  }
77
78  /// getUse - Return the operand Use in the predecessor's terminator
79  /// of the successor.
80  Use &getUse() const {
81    return It.getUse();
82  }
83};
84
85typedef PredIterator<BasicBlock, Value::user_iterator> pred_iterator;
86typedef PredIterator<const BasicBlock,
87                     Value::const_user_iterator> const_pred_iterator;
88typedef llvm::iterator_range<pred_iterator> pred_range;
89typedef llvm::iterator_range<const_pred_iterator> pred_const_range;
90
91inline pred_iterator pred_begin(BasicBlock *BB) { return pred_iterator(BB); }
92inline const_pred_iterator pred_begin(const BasicBlock *BB) {
93  return const_pred_iterator(BB);
94}
95inline pred_iterator pred_end(BasicBlock *BB) { return pred_iterator(BB, true);}
96inline const_pred_iterator pred_end(const BasicBlock *BB) {
97  return const_pred_iterator(BB, true);
98}
99inline bool pred_empty(const BasicBlock *BB) {
100  return pred_begin(BB) == pred_end(BB);
101}
102inline pred_range predecessors(BasicBlock *BB) {
103  return pred_range(pred_begin(BB), pred_end(BB));
104}
105inline pred_const_range predecessors(const BasicBlock *BB) {
106  return pred_const_range(pred_begin(BB), pred_end(BB));
107}
108
109//===----------------------------------------------------------------------===//
110// BasicBlock succ_iterator definition
111//===----------------------------------------------------------------------===//
112
113template <class Term_, class BB_>           // Successor Iterator
114class SuccIterator : public std::iterator<std::random_access_iterator_tag, BB_,
115                                          int, BB_ *, BB_ *> {
116  typedef std::iterator<std::random_access_iterator_tag, BB_, int, BB_ *, BB_ *>
117  super;
118
119public:
120  typedef typename super::pointer pointer;
121  typedef typename super::reference reference;
122
123private:
124  Term_ Term;
125  unsigned idx;
126  typedef SuccIterator<Term_, BB_> Self;
127
128  inline bool index_is_valid(int idx) {
129    return idx >= 0 && (unsigned) idx < Term->getNumSuccessors();
130  }
131
132  /// \brief Proxy object to allow write access in operator[]
133  class SuccessorProxy {
134    Self it;
135
136  public:
137    explicit SuccessorProxy(const Self &it) : it(it) {}
138
139    SuccessorProxy(const SuccessorProxy&) = default;
140
141    SuccessorProxy &operator=(SuccessorProxy r) {
142      *this = reference(r);
143      return *this;
144    }
145
146    SuccessorProxy &operator=(reference r) {
147      it.Term->setSuccessor(it.idx, r);
148      return *this;
149    }
150
151    operator reference() const { return *it; }
152  };
153
154public:
155  explicit inline SuccIterator(Term_ T) : Term(T), idx(0) {// begin iterator
156  }
157  inline SuccIterator(Term_ T, bool)                       // end iterator
158    : Term(T) {
159    if (Term)
160      idx = Term->getNumSuccessors();
161    else
162      // Term == NULL happens, if a basic block is not fully constructed and
163      // consequently getTerminator() returns NULL. In this case we construct a
164      // SuccIterator which describes a basic block that has zero successors.
165      // Defining SuccIterator for incomplete and malformed CFGs is especially
166      // useful for debugging.
167      idx = 0;
168  }
169
170  /// getSuccessorIndex - This is used to interface between code that wants to
171  /// operate on terminator instructions directly.
172  unsigned getSuccessorIndex() const { return idx; }
173
174  inline bool operator==(const Self& x) const { return idx == x.idx; }
175  inline bool operator!=(const Self& x) const { return !operator==(x); }
176
177  inline reference operator*() const { return Term->getSuccessor(idx); }
178  inline pointer operator->() const { return operator*(); }
179
180  inline Self& operator++() { ++idx; return *this; } // Preincrement
181
182  inline Self operator++(int) { // Postincrement
183    Self tmp = *this; ++*this; return tmp;
184  }
185
186  inline Self& operator--() { --idx; return *this; }  // Predecrement
187  inline Self operator--(int) { // Postdecrement
188    Self tmp = *this; --*this; return tmp;
189  }
190
191  inline bool operator<(const Self& x) const {
192    assert(Term == x.Term && "Cannot compare iterators of different blocks!");
193    return idx < x.idx;
194  }
195
196  inline bool operator<=(const Self& x) const {
197    assert(Term == x.Term && "Cannot compare iterators of different blocks!");
198    return idx <= x.idx;
199  }
200  inline bool operator>=(const Self& x) const {
201    assert(Term == x.Term && "Cannot compare iterators of different blocks!");
202    return idx >= x.idx;
203  }
204
205  inline bool operator>(const Self& x) const {
206    assert(Term == x.Term && "Cannot compare iterators of different blocks!");
207    return idx > x.idx;
208  }
209
210  inline Self& operator+=(int Right) {
211    unsigned new_idx = idx + Right;
212    assert(index_is_valid(new_idx) && "Iterator index out of bound");
213    idx = new_idx;
214    return *this;
215  }
216
217  inline Self operator+(int Right) const {
218    Self tmp = *this;
219    tmp += Right;
220    return tmp;
221  }
222
223  inline Self& operator-=(int Right) {
224    return operator+=(-Right);
225  }
226
227  inline Self operator-(int Right) const {
228    return operator+(-Right);
229  }
230
231  inline int operator-(const Self& x) const {
232    assert(Term == x.Term && "Cannot work on iterators of different blocks!");
233    int distance = idx - x.idx;
234    return distance;
235  }
236
237  inline SuccessorProxy operator[](int offset) {
238   Self tmp = *this;
239   tmp += offset;
240   return SuccessorProxy(tmp);
241  }
242
243  /// Get the source BB of this iterator.
244  inline BB_ *getSource() {
245    assert(Term && "Source not available, if basic block was malformed");
246    return Term->getParent();
247  }
248};
249
250typedef SuccIterator<TerminatorInst*, BasicBlock> succ_iterator;
251typedef SuccIterator<const TerminatorInst*,
252                     const BasicBlock> succ_const_iterator;
253typedef llvm::iterator_range<succ_iterator> succ_range;
254typedef llvm::iterator_range<succ_const_iterator> succ_const_range;
255
256inline succ_iterator succ_begin(BasicBlock *BB) {
257  return succ_iterator(BB->getTerminator());
258}
259inline succ_const_iterator succ_begin(const BasicBlock *BB) {
260  return succ_const_iterator(BB->getTerminator());
261}
262inline succ_iterator succ_end(BasicBlock *BB) {
263  return succ_iterator(BB->getTerminator(), true);
264}
265inline succ_const_iterator succ_end(const BasicBlock *BB) {
266  return succ_const_iterator(BB->getTerminator(), true);
267}
268inline bool succ_empty(const BasicBlock *BB) {
269  return succ_begin(BB) == succ_end(BB);
270}
271inline succ_range successors(BasicBlock *BB) {
272  return succ_range(succ_begin(BB), succ_end(BB));
273}
274inline succ_const_range successors(const BasicBlock *BB) {
275  return succ_const_range(succ_begin(BB), succ_end(BB));
276}
277
278
279template <typename T, typename U> struct isPodLike<SuccIterator<T, U> > {
280  static const bool value = isPodLike<T>::value;
281};
282
283
284
285//===--------------------------------------------------------------------===//
286// GraphTraits specializations for basic block graphs (CFGs)
287//===--------------------------------------------------------------------===//
288
289// Provide specializations of GraphTraits to be able to treat a function as a
290// graph of basic blocks...
291
292template <> struct GraphTraits<BasicBlock*> {
293  typedef BasicBlock NodeType;
294  typedef succ_iterator ChildIteratorType;
295
296  static NodeType *getEntryNode(BasicBlock *BB) { return BB; }
297  static inline ChildIteratorType child_begin(NodeType *N) {
298    return succ_begin(N);
299  }
300  static inline ChildIteratorType child_end(NodeType *N) {
301    return succ_end(N);
302  }
303};
304
305template <> struct GraphTraits<const BasicBlock*> {
306  typedef const BasicBlock NodeType;
307  typedef succ_const_iterator ChildIteratorType;
308
309  static NodeType *getEntryNode(const BasicBlock *BB) { return BB; }
310
311  static inline ChildIteratorType child_begin(NodeType *N) {
312    return succ_begin(N);
313  }
314  static inline ChildIteratorType child_end(NodeType *N) {
315    return succ_end(N);
316  }
317};
318
319// Provide specializations of GraphTraits to be able to treat a function as a
320// graph of basic blocks... and to walk it in inverse order.  Inverse order for
321// a function is considered to be when traversing the predecessor edges of a BB
322// instead of the successor edges.
323//
324template <> struct GraphTraits<Inverse<BasicBlock*> > {
325  typedef BasicBlock NodeType;
326  typedef pred_iterator ChildIteratorType;
327  static NodeType *getEntryNode(Inverse<BasicBlock *> G) { return G.Graph; }
328  static inline ChildIteratorType child_begin(NodeType *N) {
329    return pred_begin(N);
330  }
331  static inline ChildIteratorType child_end(NodeType *N) {
332    return pred_end(N);
333  }
334};
335
336template <> struct GraphTraits<Inverse<const BasicBlock*> > {
337  typedef const BasicBlock NodeType;
338  typedef const_pred_iterator ChildIteratorType;
339  static NodeType *getEntryNode(Inverse<const BasicBlock*> G) {
340    return G.Graph;
341  }
342  static inline ChildIteratorType child_begin(NodeType *N) {
343    return pred_begin(N);
344  }
345  static inline ChildIteratorType child_end(NodeType *N) {
346    return pred_end(N);
347  }
348};
349
350
351
352//===--------------------------------------------------------------------===//
353// GraphTraits specializations for function basic block graphs (CFGs)
354//===--------------------------------------------------------------------===//
355
356// Provide specializations of GraphTraits to be able to treat a function as a
357// graph of basic blocks... these are the same as the basic block iterators,
358// except that the root node is implicitly the first node of the function.
359//
360template <> struct GraphTraits<Function*> : public GraphTraits<BasicBlock*> {
361  static NodeType *getEntryNode(Function *F) { return &F->getEntryBlock(); }
362
363  // nodes_iterator/begin/end - Allow iteration over all nodes in the graph
364  typedef Function::iterator nodes_iterator;
365  static nodes_iterator nodes_begin(Function *F) { return F->begin(); }
366  static nodes_iterator nodes_end  (Function *F) { return F->end(); }
367  static size_t         size       (Function *F) { return F->size(); }
368};
369template <> struct GraphTraits<const Function*> :
370  public GraphTraits<const BasicBlock*> {
371  static NodeType *getEntryNode(const Function *F) {return &F->getEntryBlock();}
372
373  // nodes_iterator/begin/end - Allow iteration over all nodes in the graph
374  typedef Function::const_iterator nodes_iterator;
375  static nodes_iterator nodes_begin(const Function *F) { return F->begin(); }
376  static nodes_iterator nodes_end  (const Function *F) { return F->end(); }
377  static size_t         size       (const Function *F) { return F->size(); }
378};
379
380
381// Provide specializations of GraphTraits to be able to treat a function as a
382// graph of basic blocks... and to walk it in inverse order.  Inverse order for
383// a function is considered to be when traversing the predecessor edges of a BB
384// instead of the successor edges.
385//
386template <> struct GraphTraits<Inverse<Function*> > :
387  public GraphTraits<Inverse<BasicBlock*> > {
388  static NodeType *getEntryNode(Inverse<Function*> G) {
389    return &G.Graph->getEntryBlock();
390  }
391};
392template <> struct GraphTraits<Inverse<const Function*> > :
393  public GraphTraits<Inverse<const BasicBlock*> > {
394  static NodeType *getEntryNode(Inverse<const Function *> G) {
395    return &G.Graph->getEntryBlock();
396  }
397};
398
399} // End llvm namespace
400
401#endif
402