ExplodedGraph.h revision d0b080664bc6514793351a2e2a87ce67214f5306 
1//=-- ExplodedGraph.h - Local, Path-Sens. "Exploded Graph" -*- 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 the template classes ExplodedNode and ExplodedGraph,
11//  which represent a path-sensitive, intra-procedural "exploded graph."
12//  See "Precise interprocedural dataflow analysis via graph reachability"
13//  by Reps, Horwitz, and Sagiv
14//  (http://portal.acm.org/citation.cfm?id=199462) for the definition of an
15//  exploded graph.
16//
17//===----------------------------------------------------------------------===//
18
19#ifndef LLVM_CLANG_GR_EXPLODEDGRAPH
20#define LLVM_CLANG_GR_EXPLODEDGRAPH
21
22#include "clang/Analysis/ProgramPoint.h"
23#include "clang/Analysis/AnalysisContext.h"
24#include "clang/AST/Decl.h"
25#include "llvm/ADT/SmallVector.h"
26#include "llvm/ADT/FoldingSet.h"
27#include "llvm/ADT/SmallPtrSet.h"
28#include "llvm/Support/Allocator.h"
29#include "llvm/ADT/OwningPtr.h"
30#include "llvm/ADT/GraphTraits.h"
31#include "llvm/ADT/DepthFirstIterator.h"
32#include "llvm/Support/Casting.h"
33#include "clang/Analysis/Support/BumpVector.h"
34#include "clang/StaticAnalyzer/Core/PathSensitive/ProgramState.h"
35
36namespace clang {
37
38class CFG;
39
40namespace ento {
41
42class ExplodedGraph;
43
44//===----------------------------------------------------------------------===//
45// ExplodedGraph "implementation" classes.  These classes are not typed to
46// contain a specific kind of state.  Typed-specialized versions are defined
47// on top of these classes.
48//===----------------------------------------------------------------------===//
49
50// ExplodedNode is not constified all over the engine because we need to add
51// successors to it at any time after creating it.
52
53class ExplodedNode : public llvm::FoldingSetNode {
54  friend class ExplodedGraph;
55  friend class CoreEngine;
56  friend class NodeBuilder;
57  friend class StmtNodeBuilder;
58  friend class BranchNodeBuilder;
59  friend class IndirectGotoNodeBuilder;
60  friend class SwitchNodeBuilder;
61  friend class EndOfFunctionNodeBuilder;
62
63  class NodeGroup {
64    enum { Size1 = 0x0, SizeOther = 0x1, AuxFlag = 0x2, Mask = 0x3 };
65    uintptr_t P;
66
67    unsigned getKind() const {
68      return P & 0x1;
69    }
70
71    void *getPtr() const {
72      assert (!getFlag());
73      return reinterpret_cast<void*>(P & ~Mask);
74    }
75
76    ExplodedNode *getNode() const {
77      return reinterpret_cast<ExplodedNode*>(getPtr());
78    }
79
80  public:
81    NodeGroup() : P(0) {}
82
83    ExplodedNode **begin() const;
84
85    ExplodedNode **end() const;
86
87    unsigned size() const;
88
89    bool empty() const { return (P & ~Mask) == 0; }
90
91    void addNode(ExplodedNode *N, ExplodedGraph &G);
92
93    void replaceNode(ExplodedNode *node);
94
95    void setFlag() {
96      assert(P == 0);
97      P = AuxFlag;
98    }
99
100    bool getFlag() const {
101      return P & AuxFlag ? true : false;
102    }
103  };
104
105  /// Location - The program location (within a function body) associated
106  ///  with this node.
107  const ProgramPoint Location;
108
109  /// State - The state associated with this node.
110  const ProgramState *State;
111
112  /// Preds - The predecessors of this node.
113  NodeGroup Preds;
114
115  /// Succs - The successors of this node.
116  NodeGroup Succs;
117
118public:
119
120  explicit ExplodedNode(const ProgramPoint &loc, const ProgramState *state)
121    : Location(loc), State(state) {
122    const_cast<ProgramState*>(State)->incrementReferenceCount();
123  }
124
125  ~ExplodedNode() {
126    const_cast<ProgramState*>(State)->decrementReferenceCount();
127  }
128
129  /// getLocation - Returns the edge associated with the given node.
130  ProgramPoint getLocation() const { return Location; }
131
132  const LocationContext *getLocationContext() const {
133    return getLocation().getLocationContext();
134  }
135
136  const Decl &getCodeDecl() const { return *getLocationContext()->getDecl(); }
137
138  CFG &getCFG() const { return *getLocationContext()->getCFG(); }
139
140  ParentMap &getParentMap() const {return getLocationContext()->getParentMap();}
141
142  template <typename T>
143  T &getAnalysis() const {
144    return *getLocationContext()->getAnalysis<T>();
145  }
146
147  const ProgramState *getState() const { return State; }
148
149  template <typename T>
150  const T* getLocationAs() const { return llvm::dyn_cast<T>(&Location); }
151
152  static void Profile(llvm::FoldingSetNodeID &ID,
153                      const ProgramPoint &Loc, const ProgramState *state) {
154    ID.Add(Loc);
155    ID.AddPointer(state);
156  }
157
158  void Profile(llvm::FoldingSetNodeID& ID) const {
159    Profile(ID, getLocation(), getState());
160  }
161
162  /// addPredeccessor - Adds a predecessor to the current node, and
163  ///  in tandem add this node as a successor of the other node.
164  void addPredecessor(ExplodedNode *V, ExplodedGraph &G);
165
166  unsigned succ_size() const { return Succs.size(); }
167  unsigned pred_size() const { return Preds.size(); }
168  bool succ_empty() const { return Succs.empty(); }
169  bool pred_empty() const { return Preds.empty(); }
170
171  bool isSink() const { return Succs.getFlag(); }
172  void markAsSink() { Succs.setFlag(); }
173
174  ExplodedNode *getFirstPred() {
175    return pred_empty() ? NULL : *(pred_begin());
176  }
177
178  const ExplodedNode *getFirstPred() const {
179    return const_cast<ExplodedNode*>(this)->getFirstPred();
180  }
181
182  // Iterators over successor and predecessor vertices.
183  typedef ExplodedNode**       succ_iterator;
184  typedef const ExplodedNode* const * const_succ_iterator;
185  typedef ExplodedNode**       pred_iterator;
186  typedef const ExplodedNode* const * const_pred_iterator;
187
188  pred_iterator pred_begin() { return Preds.begin(); }
189  pred_iterator pred_end() { return Preds.end(); }
190
191  const_pred_iterator pred_begin() const {
192    return const_cast<ExplodedNode*>(this)->pred_begin();
193  }
194  const_pred_iterator pred_end() const {
195    return const_cast<ExplodedNode*>(this)->pred_end();
196  }
197
198  succ_iterator succ_begin() { return Succs.begin(); }
199  succ_iterator succ_end() { return Succs.end(); }
200
201  const_succ_iterator succ_begin() const {
202    return const_cast<ExplodedNode*>(this)->succ_begin();
203  }
204  const_succ_iterator succ_end() const {
205    return const_cast<ExplodedNode*>(this)->succ_end();
206  }
207
208  // For debugging.
209
210public:
211
212  class Auditor {
213  public:
214    virtual ~Auditor();
215    virtual void AddEdge(ExplodedNode *Src, ExplodedNode *Dst) = 0;
216  };
217
218  static void SetAuditor(Auditor* A);
219
220private:
221  void replaceSuccessor(ExplodedNode *node) { Succs.replaceNode(node); }
222  void replacePredecessor(ExplodedNode *node) { Preds.replaceNode(node); }
223};
224
225// FIXME: Is this class necessary?
226class InterExplodedGraphMap {
227  llvm::DenseMap<const ExplodedNode*, ExplodedNode*> M;
228  friend class ExplodedGraph;
229
230public:
231  ExplodedNode *getMappedNode(const ExplodedNode *N) const;
232
233  InterExplodedGraphMap() {}
234  virtual ~InterExplodedGraphMap() {}
235};
236
237class ExplodedGraph {
238protected:
239  friend class CoreEngine;
240
241  // Type definitions.
242  typedef SmallVector<ExplodedNode*,2>    RootsTy;
243  typedef SmallVector<ExplodedNode*,10>   EndNodesTy;
244
245  /// Roots - The roots of the simulation graph. Usually there will be only
246  /// one, but clients are free to establish multiple subgraphs within a single
247  /// SimulGraph. Moreover, these subgraphs can often merge when paths from
248  /// different roots reach the same state at the same program location.
249  RootsTy Roots;
250
251  /// EndNodes - The nodes in the simulation graph which have been
252  ///  specially marked as the endpoint of an abstract simulation path.
253  EndNodesTy EndNodes;
254
255  /// Nodes - The nodes in the graph.
256  llvm::FoldingSet<ExplodedNode> Nodes;
257
258  /// BVC - Allocator and context for allocating nodes and their predecessor
259  /// and successor groups.
260  BumpVectorContext BVC;
261
262  /// NumNodes - The number of nodes in the graph.
263  unsigned NumNodes;
264
265  /// A list of recently allocated nodes that can potentially be recycled.
266  void *recentlyAllocatedNodes;
267
268  /// A list of nodes that can be reused.
269  void *freeNodes;
270
271  /// A flag that indicates whether nodes should be recycled.
272  bool reclaimNodes;
273
274public:
275  /// getNode - Retrieve the node associated with a (Location,State) pair,
276  ///  where the 'Location' is a ProgramPoint in the CFG.  If no node for
277  ///  this pair exists, it is created.  IsNew is set to true if
278  ///  the node was freshly created.
279
280  ExplodedNode *getNode(const ProgramPoint &L, const ProgramState *State,
281                        bool* IsNew = 0);
282
283  ExplodedGraph* MakeEmptyGraph() const {
284    return new ExplodedGraph();
285  }
286
287  /// addRoot - Add an untyped node to the set of roots.
288  ExplodedNode *addRoot(ExplodedNode *V) {
289    Roots.push_back(V);
290    return V;
291  }
292
293  /// addEndOfPath - Add an untyped node to the set of EOP nodes.
294  ExplodedNode *addEndOfPath(ExplodedNode *V) {
295    EndNodes.push_back(V);
296    return V;
297  }
298
299  ExplodedGraph()
300    : NumNodes(0), recentlyAllocatedNodes(0),
301      freeNodes(0), reclaimNodes(false) {}
302
303  ~ExplodedGraph();
304
305  unsigned num_roots() const { return Roots.size(); }
306  unsigned num_eops() const { return EndNodes.size(); }
307
308  bool empty() const { return NumNodes == 0; }
309  unsigned size() const { return NumNodes; }
310
311  // Iterators.
312  typedef ExplodedNode                        NodeTy;
313  typedef llvm::FoldingSet<ExplodedNode>      AllNodesTy;
314  typedef NodeTy**                            roots_iterator;
315  typedef NodeTy* const *                     const_roots_iterator;
316  typedef NodeTy**                            eop_iterator;
317  typedef NodeTy* const *                     const_eop_iterator;
318  typedef AllNodesTy::iterator                node_iterator;
319  typedef AllNodesTy::const_iterator          const_node_iterator;
320
321  node_iterator nodes_begin() { return Nodes.begin(); }
322
323  node_iterator nodes_end() { return Nodes.end(); }
324
325  const_node_iterator nodes_begin() const { return Nodes.begin(); }
326
327  const_node_iterator nodes_end() const { return Nodes.end(); }
328
329  roots_iterator roots_begin() { return Roots.begin(); }
330
331  roots_iterator roots_end() { return Roots.end(); }
332
333  const_roots_iterator roots_begin() const { return Roots.begin(); }
334
335  const_roots_iterator roots_end() const { return Roots.end(); }
336
337  eop_iterator eop_begin() { return EndNodes.begin(); }
338
339  eop_iterator eop_end() { return EndNodes.end(); }
340
341  const_eop_iterator eop_begin() const { return EndNodes.begin(); }
342
343  const_eop_iterator eop_end() const { return EndNodes.end(); }
344
345  llvm::BumpPtrAllocator & getAllocator() { return BVC.getAllocator(); }
346  BumpVectorContext &getNodeAllocator() { return BVC; }
347
348  typedef llvm::DenseMap<const ExplodedNode*, ExplodedNode*> NodeMap;
349
350  std::pair<ExplodedGraph*, InterExplodedGraphMap*>
351  Trim(const NodeTy* const* NBeg, const NodeTy* const* NEnd,
352       llvm::DenseMap<const void*, const void*> *InverseMap = 0) const;
353
354  ExplodedGraph* TrimInternal(const ExplodedNode* const * NBeg,
355                              const ExplodedNode* const * NEnd,
356                              InterExplodedGraphMap *M,
357                    llvm::DenseMap<const void*, const void*> *InverseMap) const;
358
359  /// Enable tracking of recently allocated nodes for potential reclamation
360  /// when calling reclaimRecentlyAllocatedNodes().
361  void enableNodeReclamation() { reclaimNodes = true; }
362
363  /// Reclaim "uninteresting" nodes created since the last time this method
364  /// was called.
365  void reclaimRecentlyAllocatedNodes();
366};
367
368class ExplodedNodeSet {
369  typedef llvm::SmallPtrSet<ExplodedNode*,5> ImplTy;
370  ImplTy Impl;
371
372public:
373  ExplodedNodeSet(ExplodedNode *N) {
374    assert (N && !static_cast<ExplodedNode*>(N)->isSink());
375    Impl.insert(N);
376  }
377
378  ExplodedNodeSet() {}
379
380  inline void Add(ExplodedNode *N) {
381    if (N && !static_cast<ExplodedNode*>(N)->isSink()) Impl.insert(N);
382  }
383
384  typedef ImplTy::iterator       iterator;
385  typedef ImplTy::const_iterator const_iterator;
386
387  unsigned size() const { return Impl.size();  }
388  bool empty()    const { return Impl.empty(); }
389
390  void clear() { Impl.clear(); }
391  void insert(const ExplodedNodeSet &S) {
392    if (empty())
393      Impl = S.Impl;
394    else
395      Impl.insert(S.begin(), S.end());
396  }
397
398  inline iterator begin() { return Impl.begin(); }
399  inline iterator end()   { return Impl.end();   }
400
401  inline const_iterator begin() const { return Impl.begin(); }
402  inline const_iterator end()   const { return Impl.end();   }
403};
404
405} // end GR namespace
406
407} // end clang namespace
408
409// GraphTraits
410
411namespace llvm {
412  template<> struct GraphTraits<clang::ento::ExplodedNode*> {
413    typedef clang::ento::ExplodedNode NodeType;
414    typedef NodeType::succ_iterator  ChildIteratorType;
415    typedef llvm::df_iterator<NodeType*>      nodes_iterator;
416
417    static inline NodeType* getEntryNode(NodeType* N) {
418      return N;
419    }
420
421    static inline ChildIteratorType child_begin(NodeType* N) {
422      return N->succ_begin();
423    }
424
425    static inline ChildIteratorType child_end(NodeType* N) {
426      return N->succ_end();
427    }
428
429    static inline nodes_iterator nodes_begin(NodeType* N) {
430      return df_begin(N);
431    }
432
433    static inline nodes_iterator nodes_end(NodeType* N) {
434      return df_end(N);
435    }
436  };
437
438  template<> struct GraphTraits<const clang::ento::ExplodedNode*> {
439    typedef const clang::ento::ExplodedNode NodeType;
440    typedef NodeType::const_succ_iterator   ChildIteratorType;
441    typedef llvm::df_iterator<NodeType*>       nodes_iterator;
442
443    static inline NodeType* getEntryNode(NodeType* N) {
444      return N;
445    }
446
447    static inline ChildIteratorType child_begin(NodeType* N) {
448      return N->succ_begin();
449    }
450
451    static inline ChildIteratorType child_end(NodeType* N) {
452      return N->succ_end();
453    }
454
455    static inline nodes_iterator nodes_begin(NodeType* N) {
456      return df_begin(N);
457    }
458
459    static inline nodes_iterator nodes_end(NodeType* N) {
460      return df_end(N);
461    }
462  };
463
464} // end llvm namespace
465
466#endif
467