CFG.h revision 43d1fd449f1a0ac9d9dafa0b9569bb6b2e976198 
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#include "llvm/ADT/iterator.h"
22
23namespace llvm {
24
25//===--------------------------------------------------------------------===//
26// BasicBlock pred_iterator definition
27//===--------------------------------------------------------------------===//
28
29template <class _Ptr,  class _USE_iterator> // Predecessor Iterator
30class PredIterator : public forward_iterator<_Ptr, ptrdiff_t> {
31  typedef forward_iterator<_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 bidirectional_iterator<BB_, ptrdiff_t> {
89  const Term_ Term;
90  unsigned idx;
91  typedef bidirectional_iterator<BB_, ptrdiff_t> super;
92public:
93  typedef SuccIterator<Term_, BB_> _Self;
94  typedef typename super::pointer pointer;
95  // TODO: This can be random access iterator, need operator+ and stuff tho
96
97  inline SuccIterator(Term_ T) : Term(T), idx(0) {         // begin iterator
98    assert(T && "getTerminator returned null!");
99  }
100  inline SuccIterator(Term_ T, bool)                       // end iterator
101    : Term(T), idx(Term->getNumSuccessors()) {
102    assert(T && "getTerminator returned null!");
103  }
104
105  inline const _Self &operator=(const _Self &I) {
106    assert(Term == I.Term &&"Cannot assign iterators to two different blocks!");
107    idx = I.idx;
108    return *this;
109  }
110
111  /// getSuccessorIndex - This is used to interface between code that wants to
112  /// operate on terminator instructions directly.
113  unsigned getSuccessorIndex() const { return idx; }
114
115  inline bool operator==(const _Self& x) const { return idx == x.idx; }
116  inline bool operator!=(const _Self& x) const { return !operator==(x); }
117
118  inline pointer operator*() const { return Term->getSuccessor(idx); }
119  inline pointer operator->() const { return operator*(); }
120
121  inline _Self& operator++() { ++idx; return *this; } // Preincrement
122  inline _Self operator++(int) { // Postincrement
123    _Self tmp = *this; ++*this; return tmp;
124  }
125
126  inline _Self& operator--() { --idx; return *this; }  // Predecrement
127  inline _Self operator--(int) { // Postdecrement
128    _Self tmp = *this; --*this; return tmp;
129  }
130};
131
132typedef SuccIterator<TerminatorInst*, BasicBlock> succ_iterator;
133typedef SuccIterator<const TerminatorInst*,
134                     const BasicBlock> succ_const_iterator;
135
136inline succ_iterator succ_begin(BasicBlock *BB) {
137  return succ_iterator(BB->getTerminator());
138}
139inline succ_const_iterator succ_begin(const BasicBlock *BB) {
140  return succ_const_iterator(BB->getTerminator());
141}
142inline succ_iterator succ_end(BasicBlock *BB) {
143  return succ_iterator(BB->getTerminator(), true);
144}
145inline succ_const_iterator succ_end(const BasicBlock *BB) {
146  return succ_const_iterator(BB->getTerminator(), true);
147}
148
149
150
151//===--------------------------------------------------------------------===//
152// GraphTraits specializations for basic block graphs (CFGs)
153//===--------------------------------------------------------------------===//
154
155// Provide specializations of GraphTraits to be able to treat a function as a
156// graph of basic blocks...
157
158template <> struct GraphTraits<BasicBlock*> {
159  typedef BasicBlock NodeType;
160  typedef succ_iterator ChildIteratorType;
161
162  static NodeType *getEntryNode(BasicBlock *BB) { return BB; }
163  static inline ChildIteratorType child_begin(NodeType *N) {
164    return succ_begin(N);
165  }
166  static inline ChildIteratorType child_end(NodeType *N) {
167    return succ_end(N);
168  }
169};
170
171template <> struct GraphTraits<const BasicBlock*> {
172  typedef const BasicBlock NodeType;
173  typedef succ_const_iterator ChildIteratorType;
174
175  static NodeType *getEntryNode(const BasicBlock *BB) { return BB; }
176
177  static inline ChildIteratorType child_begin(NodeType *N) {
178    return succ_begin(N);
179  }
180  static inline ChildIteratorType child_end(NodeType *N) {
181    return succ_end(N);
182  }
183};
184
185// Provide specializations of GraphTraits to be able to treat a function as a
186// graph of basic blocks... and to walk it in inverse order.  Inverse order for
187// a function is considered to be when traversing the predecessor edges of a BB
188// instead of the successor edges.
189//
190template <> struct GraphTraits<Inverse<BasicBlock*> > {
191  typedef BasicBlock NodeType;
192  typedef pred_iterator ChildIteratorType;
193  static NodeType *getEntryNode(Inverse<BasicBlock *> G) { return G.Graph; }
194  static inline ChildIteratorType child_begin(NodeType *N) {
195    return pred_begin(N);
196  }
197  static inline ChildIteratorType child_end(NodeType *N) {
198    return pred_end(N);
199  }
200};
201
202template <> struct GraphTraits<Inverse<const BasicBlock*> > {
203  typedef const BasicBlock NodeType;
204  typedef pred_const_iterator ChildIteratorType;
205  static NodeType *getEntryNode(Inverse<const BasicBlock*> G) {
206    return G.Graph;
207  }
208  static inline ChildIteratorType child_begin(NodeType *N) {
209    return pred_begin(N);
210  }
211  static inline ChildIteratorType child_end(NodeType *N) {
212    return pred_end(N);
213  }
214};
215
216
217
218//===--------------------------------------------------------------------===//
219// GraphTraits specializations for function basic block graphs (CFGs)
220//===--------------------------------------------------------------------===//
221
222// Provide specializations of GraphTraits to be able to treat a function as a
223// graph of basic blocks... these are the same as the basic block iterators,
224// except that the root node is implicitly the first node of the function.
225//
226template <> struct GraphTraits<Function*> : public GraphTraits<BasicBlock*> {
227  static NodeType *getEntryNode(Function *F) { return &F->getEntryBlock(); }
228
229  // nodes_iterator/begin/end - Allow iteration over all nodes in the graph
230  typedef Function::iterator nodes_iterator;
231  static nodes_iterator nodes_begin(Function *F) { return F->begin(); }
232  static nodes_iterator nodes_end  (Function *F) { return F->end(); }
233};
234template <> struct GraphTraits<const Function*> :
235  public GraphTraits<const BasicBlock*> {
236  static NodeType *getEntryNode(const Function *F) {return &F->getEntryBlock();}
237
238  // nodes_iterator/begin/end - Allow iteration over all nodes in the graph
239  typedef Function::const_iterator nodes_iterator;
240  static nodes_iterator nodes_begin(const Function *F) { return F->begin(); }
241  static nodes_iterator nodes_end  (const Function *F) { return F->end(); }
242};
243
244
245// Provide specializations of GraphTraits to be able to treat a function as a
246// graph of basic blocks... and to walk it in inverse order.  Inverse order for
247// a function is considered to be when traversing the predecessor edges of a BB
248// instead of the successor edges.
249//
250template <> struct GraphTraits<Inverse<Function*> > :
251  public GraphTraits<Inverse<BasicBlock*> > {
252  static NodeType *getEntryNode(Inverse<Function*> G) {
253    return &G.Graph->getEntryBlock();
254  }
255};
256template <> struct GraphTraits<Inverse<const Function*> > :
257  public GraphTraits<Inverse<const BasicBlock*> > {
258  static NodeType *getEntryNode(Inverse<const Function *> G) {
259    return &G.Graph->getEntryBlock();
260  }
261};
262
263} // End llvm namespace
264
265#endif
266