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  typedef PredIterator<Ptr, USE_iterator> Self;
33  USE_iterator It;
34
35  inline void advancePastNonTerminators() {
36    // Loop to ignore non terminator uses (for example BlockAddresses).
37    while (!It.atEnd() && !isa<TerminatorInst>(*It))
38      ++It;
39  }
40
41public:
42  typedef typename super::pointer pointer;
43
44  PredIterator() {}
45  explicit inline PredIterator(Ptr *bb) : It(bb->use_begin()) {
46    advancePastNonTerminators();
47  }
48  inline PredIterator(Ptr *bb, bool) : It(bb->use_end()) {}
49
50  inline bool operator==(const Self& x) const { return It == x.It; }
51  inline bool operator!=(const Self& x) const { return !operator==(x); }
52
53  inline pointer operator*() const {
54    assert(!It.atEnd() && "pred_iterator out of range!");
55    return cast<TerminatorInst>(*It)->getParent();
56  }
57  inline pointer *operator->() const { return &operator*(); }
58
59  inline Self& operator++() {   // Preincrement
60    assert(!It.atEnd() && "pred_iterator out of range!");
61    ++It; advancePastNonTerminators();
62    return *this;
63  }
64
65  inline Self operator++(int) { // Postincrement
66    Self tmp = *this; ++*this; return tmp;
67  }
68
69  /// getOperandNo - Return the operand number in the predecessor's
70  /// terminator of the successor.
71  unsigned getOperandNo() const {
72    return It.getOperandNo();
73  }
74};
75
76typedef PredIterator<BasicBlock, Value::use_iterator> pred_iterator;
77typedef PredIterator<const BasicBlock,
78                     Value::const_use_iterator> const_pred_iterator;
79
80inline pred_iterator pred_begin(BasicBlock *BB) { return pred_iterator(BB); }
81inline const_pred_iterator pred_begin(const BasicBlock *BB) {
82  return const_pred_iterator(BB);
83}
84inline pred_iterator pred_end(BasicBlock *BB) { return pred_iterator(BB, true);}
85inline const_pred_iterator pred_end(const BasicBlock *BB) {
86  return const_pred_iterator(BB, true);
87}
88
89
90
91//===----------------------------------------------------------------------===//
92// BasicBlock succ_iterator definition
93//===----------------------------------------------------------------------===//
94
95template <class Term_, class BB_>           // Successor Iterator
96class SuccIterator : public std::iterator<std::bidirectional_iterator_tag,
97                                          BB_, ptrdiff_t> {
98  const Term_ Term;
99  unsigned idx;
100  typedef std::iterator<std::bidirectional_iterator_tag, BB_, ptrdiff_t> super;
101  typedef SuccIterator<Term_, BB_> Self;
102
103  inline bool index_is_valid(int idx) {
104    return idx >= 0 && (unsigned) idx < Term->getNumSuccessors();
105  }
106
107public:
108  typedef typename super::pointer pointer;
109  // TODO: This can be random access iterator, only operator[] missing.
110
111  explicit inline SuccIterator(Term_ T) : Term(T), idx(0) {// begin iterator
112  }
113  inline SuccIterator(Term_ T, bool)                       // end iterator
114    : Term(T) {
115    if (Term)
116      idx = Term->getNumSuccessors();
117    else
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.
123      idx = 0;
124  }
125
126  inline const Self &operator=(const Self &I) {
127    assert(Term == I.Term &&"Cannot assign iterators to two different blocks!");
128    idx = I.idx;
129    return *this;
130  }
131
132  /// getSuccessorIndex - This is used to interface between code that wants to
133  /// operate on terminator instructions directly.
134  unsigned getSuccessorIndex() const { return idx; }
135
136  inline bool operator==(const Self& x) const { return idx == x.idx; }
137  inline bool operator!=(const Self& x) const { return !operator==(x); }
138
139  inline pointer operator*() const { return Term->getSuccessor(idx); }
140  inline pointer operator->() const { return operator*(); }
141
142  inline Self& operator++() { ++idx; return *this; } // Preincrement
143
144  inline Self operator++(int) { // Postincrement
145    Self tmp = *this; ++*this; return tmp;
146  }
147
148  inline Self& operator--() { --idx; return *this; }  // Predecrement
149  inline Self operator--(int) { // Postdecrement
150    Self tmp = *this; --*this; return tmp;
151  }
152
153  inline bool operator<(const Self& x) const {
154    assert(Term == x.Term && "Cannot compare iterators of different blocks!");
155    return idx < x.idx;
156  }
157
158  inline bool operator<=(const Self& x) const {
159    assert(Term == x.Term && "Cannot compare iterators of different blocks!");
160    return idx <= x.idx;
161  }
162  inline bool operator>=(const Self& x) const {
163    assert(Term == x.Term && "Cannot compare iterators of different blocks!");
164    return idx >= x.idx;
165  }
166
167  inline bool operator>(const Self& x) const {
168    assert(Term == x.Term && "Cannot compare iterators of different blocks!");
169    return idx > x.idx;
170  }
171
172  inline Self& operator+=(int Right) {
173    unsigned new_idx = idx + Right;
174    assert(index_is_valid(new_idx) && "Iterator index out of bound");
175    idx = new_idx;
176    return *this;
177  }
178
179  inline Self operator+(int Right) {
180    Self tmp = *this;
181    tmp += Right;
182    return tmp;
183  }
184
185  inline Self& operator-=(int Right) {
186    return operator+=(-Right);
187  }
188
189  inline Self operator-(int Right) {
190    return operator+(-Right);
191  }
192
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;
196    return distance;
197  }
198
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.
202  //
203  // inline pointer operator[](int offset) {
204  //  Self tmp = *this;
205  //  tmp += offset;
206  //  return tmp.operator*();
207  // }
208
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();
213  }
214};
215
216typedef SuccIterator<TerminatorInst*, BasicBlock> succ_iterator;
217typedef SuccIterator<const TerminatorInst*,
218                     const BasicBlock> succ_const_iterator;
219
220inline succ_iterator succ_begin(BasicBlock *BB) {
221  return succ_iterator(BB->getTerminator());
222}
223inline succ_const_iterator succ_begin(const BasicBlock *BB) {
224  return succ_const_iterator(BB->getTerminator());
225}
226inline succ_iterator succ_end(BasicBlock *BB) {
227  return succ_iterator(BB->getTerminator(), true);
228}
229inline succ_const_iterator succ_end(const BasicBlock *BB) {
230  return succ_const_iterator(BB->getTerminator(), true);
231}
232
233
234
235//===--------------------------------------------------------------------===//
236// GraphTraits specializations for basic block graphs (CFGs)
237//===--------------------------------------------------------------------===//
238
239// Provide specializations of GraphTraits to be able to treat a function as a
240// graph of basic blocks...
241
242template <> struct GraphTraits<BasicBlock*> {
243  typedef BasicBlock NodeType;
244  typedef succ_iterator ChildIteratorType;
245
246  static NodeType *getEntryNode(BasicBlock *BB) { return BB; }
247  static inline ChildIteratorType child_begin(NodeType *N) {
248    return succ_begin(N);
249  }
250  static inline ChildIteratorType child_end(NodeType *N) {
251    return succ_end(N);
252  }
253};
254
255template <> struct GraphTraits<const BasicBlock*> {
256  typedef const BasicBlock NodeType;
257  typedef succ_const_iterator ChildIteratorType;
258
259  static NodeType *getEntryNode(const BasicBlock *BB) { return BB; }
260
261  static inline ChildIteratorType child_begin(NodeType *N) {
262    return succ_begin(N);
263  }
264  static inline ChildIteratorType child_end(NodeType *N) {
265    return succ_end(N);
266  }
267};
268
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.
273//
274template <> 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);
280  }
281  static inline ChildIteratorType child_end(NodeType *N) {
282    return pred_end(N);
283  }
284};
285
286template <> struct GraphTraits<Inverse<const BasicBlock*> > {
287  typedef const BasicBlock NodeType;
288  typedef const_pred_iterator ChildIteratorType;
289  static NodeType *getEntryNode(Inverse<const BasicBlock*> G) {
290    return G.Graph;
291  }
292  static inline ChildIteratorType child_begin(NodeType *N) {
293    return pred_begin(N);
294  }
295  static inline ChildIteratorType child_end(NodeType *N) {
296    return pred_end(N);
297  }
298};
299
300
301
302//===--------------------------------------------------------------------===//
303// GraphTraits specializations for function basic block graphs (CFGs)
304//===--------------------------------------------------------------------===//
305
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.
309//
310template <> struct GraphTraits<Function*> : public GraphTraits<BasicBlock*> {
311  static NodeType *getEntryNode(Function *F) { return &F->getEntryBlock(); }
312
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};
318template <> struct GraphTraits<const Function*> :
319  public GraphTraits<const BasicBlock*> {
320  static NodeType *getEntryNode(const Function *F) {return &F->getEntryBlock();}
321
322  // nodes_iterator/begin/end - Allow iteration over all nodes in the graph
323  typedef Function::const_iterator nodes_iterator;
324  static nodes_iterator nodes_begin(const Function *F) { return F->begin(); }
325  static nodes_iterator nodes_end  (const Function *F) { return F->end(); }
326};
327
328
329// Provide specializations of GraphTraits to be able to treat a function as a
330// graph of basic blocks... and to walk it in inverse order.  Inverse order for
331// a function is considered to be when traversing the predecessor edges of a BB
332// instead of the successor edges.
333//
334template <> struct GraphTraits<Inverse<Function*> > :
335  public GraphTraits<Inverse<BasicBlock*> > {
336  static NodeType *getEntryNode(Inverse<Function*> G) {
337    return &G.Graph->getEntryBlock();
338  }
339};
340template <> struct GraphTraits<Inverse<const Function*> > :
341  public GraphTraits<Inverse<const BasicBlock*> > {
342  static NodeType *getEntryNode(Inverse<const Function *> G) {
343    return &G.Graph->getEntryBlock();
344  }
345};
346
347} // End llvm namespace
348
349#endif
350