summaryrefslogtreecommitdiff
path: root/include/llvm/Analysis/CallGraph.h
blob: 5225a89b7818202c1c73b01f5ab847a63df051f3 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
//===- CallGraph.h - Build a Module's call graph ----------------*- C++ -*-===//
//
//                     The LLVM Compiler Infrastructure
//
// This file was developed by the LLVM research group and is distributed under
// the University of Illinois Open Source License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This interface is used to build and manipulate a call graph, which is a very
// useful tool for interprocedural optimization.
//
// Every function in a module is represented as a node in the call graph.  The
// callgraph node keeps track of which functions the are called by the function
// corresponding to the node.
//
// A call graph may contain nodes where the function that they correspond to is
// null.  These 'external' nodes are used to represent control flow that is not
// represented (or analyzable) in the module.  In particular, this analysis
// builds one external node such that:
//   1. All functions in the module without internal linkage will have edges
//      from this external node, indicating that they could be called by
//      functions outside of the module.
//   2. All functions whose address is used for something more than a direct
//      call, for example being stored into a memory location will also have an
//      edge from this external node.  Since they may be called by an unknown
//      caller later, they must be tracked as such.
//
// There is a second external node added for calls that leave this module.
// Functions have a call edge to the external node iff:
//   1. The function is external, reflecting the fact that they could call
//      anything without internal linkage or that has its address taken.
//   2. The function contains an indirect function call.
//
// As an extension in the future, there may be multiple nodes with a null
// function.  These will be used when we can prove (through pointer analysis)
// that an indirect call site can call only a specific set of functions.
//
// Because of these properties, the CallGraph captures a conservative superset
// of all of the caller-callee relationships, which is useful for
// transformations.
//
// The CallGraph class also attempts to figure out what the root of the
// CallGraph is, which it currently does by looking for a function named 'main'.
// If no function named 'main' is found, the external node is used as the entry
// node, reflecting the fact that any function without internal linkage could
// be called into (which is common for libraries).
//
//===----------------------------------------------------------------------===//

#ifndef LLVM_ANALYSIS_CALLGRAPH_H
#define LLVM_ANALYSIS_CALLGRAPH_H

#include "llvm/ADT/GraphTraits.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/Pass.h"
#include "llvm/Support/CallSite.h"

namespace llvm {

class Function;
class Module;
class CallGraphNode;

//===----------------------------------------------------------------------===//
// CallGraph class definition
//
class CallGraph {
protected:
  Module *Mod;              // The module this call graph represents

  typedef std::map<const Function *, CallGraphNode *> FunctionMapTy;
  FunctionMapTy FunctionMap;    // Map from a function to its node

public:
  static const char ID; // Class identification, replacement for typeinfo
  //===---------------------------------------------------------------------
  // Accessors...
  //
  typedef FunctionMapTy::iterator iterator;
  typedef FunctionMapTy::const_iterator const_iterator;

  /// getModule - Return the module the call graph corresponds to.
  ///
  Module &getModule() const { return *Mod; }

  inline       iterator begin()       { return FunctionMap.begin(); }
  inline       iterator end()         { return FunctionMap.end();   }
  inline const_iterator begin() const { return FunctionMap.begin(); }
  inline const_iterator end()   const { return FunctionMap.end();   }

  // Subscripting operators, return the call graph node for the provided
  // function
  inline const CallGraphNode *operator[](const Function *F) const {
    const_iterator I = FunctionMap.find(F);
    assert(I != FunctionMap.end() && "Function not in callgraph!");
    return I->second;
  }
  inline CallGraphNode *operator[](const Function *F) {
    const_iterator I = FunctionMap.find(F);
    assert(I != FunctionMap.end() && "Function not in callgraph!");
    return I->second;
  }

  //Returns the CallGraphNode which is used to represent undetermined calls 
  // into the callgraph.  Override this if you want behavioural inheritance.
  virtual CallGraphNode* getExternalCallingNode() const { return 0; }
  
  //Return the root/main method in the module, or some other root node, such
  // as the externalcallingnode.  Overload these if you behavioural 
  // inheritance.
  virtual CallGraphNode* getRoot() { return 0; }
  virtual const CallGraphNode* getRoot() const { return 0; }
  
  //===---------------------------------------------------------------------
  // Functions to keep a call graph up to date with a function that has been
  // modified.
  //

  /// removeFunctionFromModule - Unlink the function from this module, returning
  /// it.  Because this removes the function from the module, the call graph
  /// node is destroyed.  This is only valid if the function does not call any
  /// other functions (ie, there are no edges in it's CGN).  The easiest way to
  /// do this is to dropAllReferences before calling this.
  ///
  Function *removeFunctionFromModule(CallGraphNode *CGN);
  Function *removeFunctionFromModule(Function *F) {
    return removeFunctionFromModule((*this)[F]);
  }

  /// changeFunction - This method changes the function associated with this
  /// CallGraphNode, for use by transformations that need to change the
  /// prototype of a Function (thus they must create a new Function and move the
  /// old code over).
  void changeFunction(Function *OldF, Function *NewF);

  /// getOrInsertFunction - This method is identical to calling operator[], but
  /// it will insert a new CallGraphNode for the specified function if one does
  /// not already exist.
  CallGraphNode *getOrInsertFunction(const Function *F);
  
  //===---------------------------------------------------------------------
  // Pass infrastructure interface glue code...
  //
protected:
  CallGraph() {}
  
public:
  virtual ~CallGraph() { destroy(); }

  /// initialize - Call this method before calling other methods, 
  /// re/initializes the state of the CallGraph.
  ///
  void initialize(Module &M);

  virtual void print(std::ostream &o, const Module *M) const;
  void print(std::ostream *o, const Module *M) const { if (o) print(*o, M); }
  void dump() const;
  
  // stub - dummy function, just ignore it
  static int stub;
protected:

  // destroy - Release memory for the call graph
  virtual void destroy();
};

//===----------------------------------------------------------------------===//
// CallGraphNode class definition
//
class CallGraphNode {
  Function *F;
  typedef std::pair<CallSite,CallGraphNode*> CallRecord;
  std::vector<CallRecord> CalledFunctions;

  CallGraphNode(const CallGraphNode &);           // Do not implement
public:
  //===---------------------------------------------------------------------
  // Accessor methods...
  //

  typedef std::vector<CallRecord>::iterator iterator;
  typedef std::vector<CallRecord>::const_iterator const_iterator;

  // getFunction - Return the function that this call graph node represents...
  Function *getFunction() const { return F; }

  inline iterator begin() { return CalledFunctions.begin(); }
  inline iterator end()   { return CalledFunctions.end();   }
  inline const_iterator begin() const { return CalledFunctions.begin(); }
  inline const_iterator end()   const { return CalledFunctions.end();   }
  inline unsigned size() const { return CalledFunctions.size(); }

  // Subscripting operator - Return the i'th called function...
  //
  CallGraphNode *operator[](unsigned i) const {
    return CalledFunctions[i].second;
  }

  /// dump - Print out this call graph node.
  ///
  void dump() const;
  void print(std::ostream &OS) const;
  void print(std::ostream *OS) const { if (OS) print(*OS); }

  //===---------------------------------------------------------------------
  // Methods to keep a call graph up to date with a function that has been
  // modified
  //

  /// removeAllCalledFunctions - As the name implies, this removes all edges
  /// from this CallGraphNode to any functions it calls.
  void removeAllCalledFunctions() {
    CalledFunctions.clear();
  }

  /// addCalledFunction add a function to the list of functions called by this
  /// one.
  void addCalledFunction(CallSite CS, CallGraphNode *M) {
    CalledFunctions.push_back(std::make_pair(CS, M));
  }

  /// removeCallEdgeTo - This method removes a *single* edge to the specified
  /// callee function.  Note that this method takes linear time, so it should be
  /// used sparingly.
  void removeCallEdgeTo(CallGraphNode *Callee);

  /// removeAnyCallEdgeTo - This method removes any call edges from this node to
  /// the specified callee function.  This takes more time to execute than
  /// removeCallEdgeTo, so it should not be used unless necessary.
  void removeAnyCallEdgeTo(CallGraphNode *Callee);

  friend class CallGraph;

  // CallGraphNode ctor - Create a node for the specified function.
  inline CallGraphNode(Function *f) : F(f) {}
};

//===----------------------------------------------------------------------===//
// GraphTraits specializations for call graphs so that they can be treated as
// graphs by the generic graph algorithms.
//

// Provide graph traits for tranversing call graphs using standard graph
// traversals.
template <> struct GraphTraits<CallGraphNode*> {
  typedef CallGraphNode NodeType;

  typedef std::pair<CallSite, CallGraphNode*> CGNPairTy;
  typedef std::pointer_to_unary_function<CGNPairTy, CallGraphNode*> CGNDerefFun;
  
  static NodeType *getEntryNode(CallGraphNode *CGN) { return CGN; }
  
  typedef mapped_iterator<NodeType::iterator, CGNDerefFun> ChildIteratorType;
  
  static inline ChildIteratorType child_begin(NodeType *N) {
    return map_iterator(N->begin(), CGNDerefFun(CGNDeref));
  }
  static inline ChildIteratorType child_end  (NodeType *N) {
    return map_iterator(N->end(), CGNDerefFun(CGNDeref));
  }
  
  static CallGraphNode *CGNDeref(CGNPairTy P) {
    return P.second;
  }
  
};

template <> struct GraphTraits<const CallGraphNode*> {
  typedef const CallGraphNode NodeType;
  typedef NodeType::const_iterator ChildIteratorType;

  static NodeType *getEntryNode(const CallGraphNode *CGN) { return CGN; }
  static inline ChildIteratorType child_begin(NodeType *N) { return N->begin();}
  static inline ChildIteratorType child_end  (NodeType *N) { return N->end(); }
};

template<> struct GraphTraits<CallGraph*> : public GraphTraits<CallGraphNode*> {
  static NodeType *getEntryNode(CallGraph *CGN) {
    return CGN->getExternalCallingNode();  // Start at the external node!
  }
  typedef std::pair<const Function*, CallGraphNode*> PairTy;
  typedef std::pointer_to_unary_function<PairTy, CallGraphNode&> DerefFun;

  // nodes_iterator/begin/end - Allow iteration over all nodes in the graph
  typedef mapped_iterator<CallGraph::iterator, DerefFun> nodes_iterator;
  static nodes_iterator nodes_begin(CallGraph *CG) {
    return map_iterator(CG->begin(), DerefFun(CGdereference));
  }
  static nodes_iterator nodes_end  (CallGraph *CG) {
    return map_iterator(CG->end(), DerefFun(CGdereference));
  }

  static CallGraphNode &CGdereference(PairTy P) {
    return *P.second;
  }
};

template<> struct GraphTraits<const CallGraph*> :
  public GraphTraits<const CallGraphNode*> {
  static NodeType *getEntryNode(const CallGraph *CGN) {
    return CGN->getExternalCallingNode();
  }
  // nodes_iterator/begin/end - Allow iteration over all nodes in the graph
  typedef CallGraph::const_iterator nodes_iterator;
  static nodes_iterator nodes_begin(const CallGraph *CG) { return CG->begin(); }
  static nodes_iterator nodes_end  (const CallGraph *CG) { return CG->end(); }
};

} // End llvm namespace

// Make sure that any clients of this file link in CallGraph.cpp
FORCE_DEFINING_FILE_TO_BE_LINKED(CallGraph)

#endif