CFG.h revision 3889a2cb05c36f30050941679d5fd55d45e6a3ed 
1//===-- llvm/Support/CFG.h - Process LLVM structures as graphs ---*- C++ -*--=//
2//
3// This file defines specializations of GraphTraits that allow Function and
4// BasicBlock graphs to be treated as proper graphs for generic algorithms.
5//
6//===----------------------------------------------------------------------===//
7
8#ifndef LLVM_CFG_H
9#define LLVM_CFG_H
10
11#include "Support/GraphTraits.h"
12#include "llvm/Function.h"
13#include "llvm/InstrTypes.h"
14#include "Support/iterator"
15
16//===--------------------------------------------------------------------===//
17// BasicBlock pred_iterator definition
18//===--------------------------------------------------------------------===//
19
20template <class _Ptr,  class _USE_iterator> // Predecessor Iterator
21class PredIterator : public bidirectional_iterator<_Ptr, ptrdiff_t> {
22  typedef bidirectional_iterator<_Ptr, ptrdiff_t> super;
23  _Ptr *BB;
24  _USE_iterator It;
25public:
26  typedef PredIterator<_Ptr,_USE_iterator> _Self;
27  typedef typename super::pointer pointer;
28
29  inline void advancePastConstants() {
30    // Loop to ignore non terminator uses (for example PHI nodes)...
31    while (It != BB->use_end() && !isa<TerminatorInst>(*It))
32      ++It;
33  }
34
35  inline PredIterator(_Ptr *bb) : BB(bb), It(bb->use_begin()) {
36    advancePastConstants();
37  }
38  inline PredIterator(_Ptr *bb, bool) : BB(bb), It(bb->use_end()) {}
39
40  inline bool operator==(const _Self& x) const { return It == x.It; }
41  inline bool operator!=(const _Self& x) const { return !operator==(x); }
42
43  inline pointer operator*() const {
44    assert(It != BB->use_end() && "pred_iterator out of range!");
45    return cast<TerminatorInst>(*It)->getParent();
46  }
47  inline pointer *operator->() const { return &(operator*()); }
48
49  inline _Self& operator++() {   // Preincrement
50    assert(It != BB->use_end() && "pred_iterator out of range!");
51    ++It; advancePastConstants();
52    return *this;
53  }
54
55  inline _Self operator++(int) { // Postincrement
56    _Self tmp = *this; ++*this; return tmp;
57  }
58
59  inline _Self& operator--() { --It; return *this; }  // Predecrement
60  inline _Self operator--(int) { // Postdecrement
61    _Self tmp = *this; --*this; return tmp;
62  }
63};
64
65typedef PredIterator<BasicBlock, Value::use_iterator> pred_iterator;
66typedef PredIterator<const BasicBlock,
67                     Value::use_const_iterator> pred_const_iterator;
68
69inline pred_iterator pred_begin(BasicBlock *BB) { return pred_iterator(BB); }
70inline pred_const_iterator pred_begin(const BasicBlock *BB) {
71  return pred_const_iterator(BB);
72}
73inline pred_iterator pred_end(BasicBlock *BB) { return pred_iterator(BB, true);}
74inline pred_const_iterator pred_end(const BasicBlock *BB) {
75  return pred_const_iterator(BB, true);
76}
77
78
79
80//===--------------------------------------------------------------------===//
81// BasicBlock succ_iterator definition
82//===--------------------------------------------------------------------===//
83
84template <class _Term, class _BB>           // Successor Iterator
85class SuccIterator : public bidirectional_iterator<_BB, ptrdiff_t> {
86  const _Term Term;
87  unsigned idx;
88  typedef bidirectional_iterator<_BB, ptrdiff_t> super;
89public:
90  typedef SuccIterator<_Term, _BB> _Self;
91  typedef typename super::pointer pointer;
92  // TODO: This can be random access iterator, need operator+ and stuff tho
93
94  inline SuccIterator(_Term T) : Term(T), idx(0) {         // begin iterator
95    assert(T && "getTerminator returned null!");
96  }
97  inline SuccIterator(_Term T, bool)                       // end iterator
98    : Term(T), idx(Term->getNumSuccessors()) {
99    assert(T && "getTerminator returned null!");
100  }
101
102  inline const _Self &operator=(const _Self &I) {
103    assert(Term == I.Term &&"Cannot assign iterators to two different blocks!");
104    idx = I.idx;
105    return *this;
106  }
107
108  inline bool operator==(const _Self& x) const { return idx == x.idx; }
109  inline bool operator!=(const _Self& x) const { return !operator==(x); }
110
111  inline pointer operator*() const { return Term->getSuccessor(idx); }
112  inline pointer operator->() const { return operator*(); }
113
114  inline _Self& operator++() { ++idx; return *this; } // Preincrement
115  inline _Self operator++(int) { // Postincrement
116    _Self tmp = *this; ++*this; return tmp;
117  }
118
119  inline _Self& operator--() { --idx; return *this; }  // Predecrement
120  inline _Self operator--(int) { // Postdecrement
121    _Self tmp = *this; --*this; return tmp;
122  }
123};
124
125typedef SuccIterator<TerminatorInst*, BasicBlock> succ_iterator;
126typedef SuccIterator<const TerminatorInst*,
127                     const BasicBlock> succ_const_iterator;
128
129inline succ_iterator succ_begin(BasicBlock *BB) {
130  return succ_iterator(BB->getTerminator());
131}
132inline succ_const_iterator succ_begin(const BasicBlock *BB) {
133  return succ_const_iterator(BB->getTerminator());
134}
135inline succ_iterator succ_end(BasicBlock *BB) {
136  return succ_iterator(BB->getTerminator(), true);
137}
138inline succ_const_iterator succ_end(const BasicBlock *BB) {
139  return succ_const_iterator(BB->getTerminator(), true);
140}
141
142
143
144//===--------------------------------------------------------------------===//
145// GraphTraits specializations for basic block graphs (CFGs)
146//===--------------------------------------------------------------------===//
147
148// Provide specializations of GraphTraits to be able to treat a function as a
149// graph of basic blocks...
150
151template <> struct GraphTraits<BasicBlock*> {
152  typedef BasicBlock NodeType;
153  typedef succ_iterator ChildIteratorType;
154
155  static NodeType *getEntryNode(BasicBlock *BB) { return BB; }
156  static inline ChildIteratorType child_begin(NodeType *N) {
157    return succ_begin(N);
158  }
159  static inline ChildIteratorType child_end(NodeType *N) {
160    return succ_end(N);
161  }
162};
163
164template <> struct GraphTraits<const BasicBlock*> {
165  typedef const BasicBlock NodeType;
166  typedef succ_const_iterator ChildIteratorType;
167
168  static NodeType *getEntryNode(const BasicBlock *BB) { return BB; }
169
170  static inline ChildIteratorType child_begin(NodeType *N) {
171    return succ_begin(N);
172  }
173  static inline ChildIteratorType child_end(NodeType *N) {
174    return succ_end(N);
175  }
176};
177
178// Provide specializations of GraphTraits to be able to treat a function as a
179// graph of basic blocks... and to walk it in inverse order.  Inverse order for
180// a function is considered to be when traversing the predecessor edges of a BB
181// instead of the successor edges.
182//
183template <> struct GraphTraits<Inverse<BasicBlock*> > {
184  typedef BasicBlock NodeType;
185  typedef pred_iterator ChildIteratorType;
186  static NodeType *getEntryNode(Inverse<BasicBlock *> G) { return G.Graph; }
187  static inline ChildIteratorType child_begin(NodeType *N) {
188    return pred_begin(N);
189  }
190  static inline ChildIteratorType child_end(NodeType *N) {
191    return pred_end(N);
192  }
193};
194
195template <> struct GraphTraits<Inverse<const BasicBlock*> > {
196  typedef const BasicBlock NodeType;
197  typedef pred_const_iterator ChildIteratorType;
198  static NodeType *getEntryNode(Inverse<const BasicBlock*> G) {
199    return G.Graph;
200  }
201  static inline ChildIteratorType child_begin(NodeType *N) {
202    return pred_begin(N);
203  }
204  static inline ChildIteratorType child_end(NodeType *N) {
205    return pred_end(N);
206  }
207};
208
209
210
211//===--------------------------------------------------------------------===//
212// GraphTraits specializations for function basic block graphs (CFGs)
213//===--------------------------------------------------------------------===//
214
215// Provide specializations of GraphTraits to be able to treat a function as a
216// graph of basic blocks... these are the same as the basic block iterators,
217// except that the root node is implicitly the first node of the function.
218//
219template <> struct GraphTraits<Function*> : public GraphTraits<BasicBlock*> {
220  static NodeType *getEntryNode(Function *F) { return &F->getEntryNode(); }
221
222  // nodes_iterator/begin/end - Allow iteration over all nodes in the graph
223  typedef Function::iterator nodes_iterator;
224  static nodes_iterator nodes_begin(Function *F) { return F->begin(); }
225  static nodes_iterator nodes_end  (Function *F) { return F->end(); }
226};
227template <> struct GraphTraits<const Function*> :
228  public GraphTraits<const BasicBlock*> {
229  static NodeType *getEntryNode(const Function *F) { return &F->getEntryNode();}
230
231  // nodes_iterator/begin/end - Allow iteration over all nodes in the graph
232  typedef Function::const_iterator nodes_iterator;
233  static nodes_iterator nodes_begin(const Function *F) { return F->begin(); }
234  static nodes_iterator nodes_end  (const Function *F) { return F->end(); }
235};
236
237
238// Provide specializations of GraphTraits to be able to treat a function as a
239// graph of basic blocks... and to walk it in inverse order.  Inverse order for
240// a function is considered to be when traversing the predecessor edges of a BB
241// instead of the successor edges.
242//
243template <> struct GraphTraits<Inverse<Function*> > :
244  public GraphTraits<Inverse<BasicBlock*> > {
245  static NodeType *getEntryNode(Inverse<Function*> G) {
246    return &G.Graph->getEntryNode();
247  }
248};
249template <> struct GraphTraits<Inverse<const Function*> > :
250  public GraphTraits<Inverse<const BasicBlock*> > {
251  static NodeType *getEntryNode(Inverse<const Function *> G) {
252    return &G.Graph->getEntryNode();
253  }
254};
255
256#endif
257