ExplodedGraph.h revision 72e93068c9f2a2f05f5932cdd917c0d2961f11d9
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 BranchNodeBuilder;
58  friend class IndirectGotoNodeBuilder;
59  friend class SwitchNodeBuilder;
60  friend class EndOfFunctionNodeBuilder;
61
62  class NodeGroup {
63    enum { Size1 = 0x0, SizeOther = 0x1, AuxFlag = 0x2, Mask = 0x3 };
64    uintptr_t P;
65
66    unsigned getKind() const {
67      return P & 0x1;
68    }
69
70    void *getPtr() const {
71      assert (!getFlag());
72      return reinterpret_cast<void*>(P & ~Mask);
73    }
74
75    ExplodedNode *getNode() const {
76      return reinterpret_cast<ExplodedNode*>(getPtr());
77    }
78
79  public:
80    NodeGroup() : P(0) {}
81
82    ExplodedNode **begin() const;
83
84    ExplodedNode **end() const;
85
86    unsigned size() const;
87
88    bool empty() const { return (P & ~Mask) == 0; }
89
90    void addNode(ExplodedNode *N, ExplodedGraph &G);
91
92    void replaceNode(ExplodedNode *node);
93
94    void setFlag() {
95      assert(P == 0);
96      P = AuxFlag;
97    }
98
99    bool getFlag() const {
100      return P & AuxFlag ? true : false;
101    }
102  };
103
104  /// Location - The program location (within a function body) associated
105  ///  with this node.
106  const ProgramPoint Location;
107
108  /// State - The state associated with this node.
109  ProgramStateRef State;
110
111  /// Preds - The predecessors of this node.
112  NodeGroup Preds;
113
114  /// Succs - The successors of this node.
115  NodeGroup Succs;
116
117public:
118
119  explicit ExplodedNode(const ProgramPoint &loc, ProgramStateRef state,
120                        bool IsSink)
121    : Location(loc), State(state) {
122    if (IsSink)
123      Succs.setFlag();
124  }
125
126  ~ExplodedNode() {}
127
128  /// getLocation - Returns the edge associated with the given node.
129  ProgramPoint getLocation() const { return Location; }
130
131  const LocationContext *getLocationContext() const {
132    return getLocation().getLocationContext();
133  }
134
135  const Decl &getCodeDecl() const { return *getLocationContext()->getDecl(); }
136
137  CFG &getCFG() const { return *getLocationContext()->getCFG(); }
138
139  ParentMap &getParentMap() const {return getLocationContext()->getParentMap();}
140
141  template <typename T>
142  T &getAnalysis() const {
143    return *getLocationContext()->getAnalysis<T>();
144  }
145
146  ProgramStateRef getState() const { return State; }
147
148  template <typename T>
149  const T* getLocationAs() const { return llvm::dyn_cast<T>(&Location); }
150
151  static void Profile(llvm::FoldingSetNodeID &ID,
152                      const ProgramPoint &Loc,
153                      ProgramStateRef state,
154                      bool IsSink) {
155    ID.Add(Loc);
156    ID.AddPointer(state.getPtr());
157    ID.AddBoolean(IsSink);
158  }
159
160  void Profile(llvm::FoldingSetNodeID& ID) const {
161    Profile(ID, getLocation(), getState(), isSink());
162  }
163
164  /// addPredeccessor - Adds a predecessor to the current node, and
165  ///  in tandem add this node as a successor of the other node.
166  void addPredecessor(ExplodedNode *V, ExplodedGraph &G);
167
168  unsigned succ_size() const { return Succs.size(); }
169  unsigned pred_size() const { return Preds.size(); }
170  bool succ_empty() const { return Succs.empty(); }
171  bool pred_empty() const { return Preds.empty(); }
172
173  bool isSink() const { return Succs.getFlag(); }
174
175  ExplodedNode *getFirstPred() {
176    return pred_empty() ? NULL : *(pred_begin());
177  }
178
179  const ExplodedNode *getFirstPred() const {
180    return const_cast<ExplodedNode*>(this)->getFirstPred();
181  }
182
183  // Iterators over successor and predecessor vertices.
184  typedef ExplodedNode**       succ_iterator;
185  typedef const ExplodedNode* const * const_succ_iterator;
186  typedef ExplodedNode**       pred_iterator;
187  typedef const ExplodedNode* const * const_pred_iterator;
188
189  pred_iterator pred_begin() { return Preds.begin(); }
190  pred_iterator pred_end() { return Preds.end(); }
191
192  const_pred_iterator pred_begin() const {
193    return const_cast<ExplodedNode*>(this)->pred_begin();
194  }
195  const_pred_iterator pred_end() const {
196    return const_cast<ExplodedNode*>(this)->pred_end();
197  }
198
199  succ_iterator succ_begin() { return Succs.begin(); }
200  succ_iterator succ_end() { return Succs.end(); }
201
202  const_succ_iterator succ_begin() const {
203    return const_cast<ExplodedNode*>(this)->succ_begin();
204  }
205  const_succ_iterator succ_end() const {
206    return const_cast<ExplodedNode*>(this)->succ_end();
207  }
208
209  // For debugging.
210
211public:
212
213  class Auditor {
214  public:
215    virtual ~Auditor();
216    virtual void AddEdge(ExplodedNode *Src, ExplodedNode *Dst) = 0;
217  };
218
219  static void SetAuditor(Auditor* A);
220
221private:
222  void replaceSuccessor(ExplodedNode *node) { Succs.replaceNode(node); }
223  void replacePredecessor(ExplodedNode *node) { Preds.replaceNode(node); }
224};
225
226// FIXME: Is this class necessary?
227class InterExplodedGraphMap {
228  virtual void anchor();
229  llvm::DenseMap<const ExplodedNode*, ExplodedNode*> M;
230  friend class ExplodedGraph;
231
232public:
233  ExplodedNode *getMappedNode(const ExplodedNode *N) const;
234
235  InterExplodedGraphMap() {}
236  virtual ~InterExplodedGraphMap() {}
237};
238
239class ExplodedGraph {
240protected:
241  friend class CoreEngine;
242
243  // Type definitions.
244  typedef SmallVector<ExplodedNode*,2>    RootsTy;
245  typedef SmallVector<ExplodedNode*,10>   EndNodesTy;
246
247  /// Roots - The roots of the simulation graph. Usually there will be only
248  /// one, but clients are free to establish multiple subgraphs within a single
249  /// SimulGraph. Moreover, these subgraphs can often merge when paths from
250  /// different roots reach the same state at the same program location.
251  RootsTy Roots;
252
253  /// EndNodes - The nodes in the simulation graph which have been
254  ///  specially marked as the endpoint of an abstract simulation path.
255  EndNodesTy EndNodes;
256
257  /// Nodes - The nodes in the graph.
258  llvm::FoldingSet<ExplodedNode> Nodes;
259
260  /// BVC - Allocator and context for allocating nodes and their predecessor
261  /// and successor groups.
262  BumpVectorContext BVC;
263
264  /// NumNodes - The number of nodes in the graph.
265  unsigned NumNodes;
266
267  /// A list of recently allocated nodes that can potentially be recycled.
268  void *recentlyAllocatedNodes;
269
270  /// A list of nodes that can be reused.
271  void *freeNodes;
272
273  /// A flag that indicates whether nodes should be recycled.
274  bool reclaimNodes;
275
276  /// Counter to determine when to reclaim nodes.
277  unsigned reclaimCounter;
278
279public:
280
281  /// \brief Retrieve the node associated with a (Location,State) pair,
282  ///  where the 'Location' is a ProgramPoint in the CFG.  If no node for
283  ///  this pair exists, it is created. IsNew is set to true if
284  ///  the node was freshly created.
285  ExplodedNode *getNode(const ProgramPoint &L, ProgramStateRef State,
286                        bool IsSink = false,
287                        bool* IsNew = 0);
288
289  ExplodedGraph* MakeEmptyGraph() const {
290    return new ExplodedGraph();
291  }
292
293  /// addRoot - Add an untyped node to the set of roots.
294  ExplodedNode *addRoot(ExplodedNode *V) {
295    Roots.push_back(V);
296    return V;
297  }
298
299  /// addEndOfPath - Add an untyped node to the set of EOP nodes.
300  ExplodedNode *addEndOfPath(ExplodedNode *V) {
301    EndNodes.push_back(V);
302    return V;
303  }
304
305  ExplodedGraph();
306
307  ~ExplodedGraph();
308
309  unsigned num_roots() const { return Roots.size(); }
310  unsigned num_eops() const { return EndNodes.size(); }
311
312  bool empty() const { return NumNodes == 0; }
313  unsigned size() const { return NumNodes; }
314
315  // Iterators.
316  typedef ExplodedNode                        NodeTy;
317  typedef llvm::FoldingSet<ExplodedNode>      AllNodesTy;
318  typedef NodeTy**                            roots_iterator;
319  typedef NodeTy* const *                     const_roots_iterator;
320  typedef NodeTy**                            eop_iterator;
321  typedef NodeTy* const *                     const_eop_iterator;
322  typedef AllNodesTy::iterator                node_iterator;
323  typedef AllNodesTy::const_iterator          const_node_iterator;
324
325  node_iterator nodes_begin() { return Nodes.begin(); }
326
327  node_iterator nodes_end() { return Nodes.end(); }
328
329  const_node_iterator nodes_begin() const { return Nodes.begin(); }
330
331  const_node_iterator nodes_end() const { return Nodes.end(); }
332
333  roots_iterator roots_begin() { return Roots.begin(); }
334
335  roots_iterator roots_end() { return Roots.end(); }
336
337  const_roots_iterator roots_begin() const { return Roots.begin(); }
338
339  const_roots_iterator roots_end() const { return Roots.end(); }
340
341  eop_iterator eop_begin() { return EndNodes.begin(); }
342
343  eop_iterator eop_end() { return EndNodes.end(); }
344
345  const_eop_iterator eop_begin() const { return EndNodes.begin(); }
346
347  const_eop_iterator eop_end() const { return EndNodes.end(); }
348
349  llvm::BumpPtrAllocator & getAllocator() { return BVC.getAllocator(); }
350  BumpVectorContext &getNodeAllocator() { return BVC; }
351
352  typedef llvm::DenseMap<const ExplodedNode*, ExplodedNode*> NodeMap;
353
354  std::pair<ExplodedGraph*, InterExplodedGraphMap*>
355  Trim(const NodeTy* const* NBeg, const NodeTy* const* NEnd,
356       llvm::DenseMap<const void*, const void*> *InverseMap = 0) const;
357
358  ExplodedGraph* TrimInternal(const ExplodedNode* const * NBeg,
359                              const ExplodedNode* const * NEnd,
360                              InterExplodedGraphMap *M,
361                    llvm::DenseMap<const void*, const void*> *InverseMap) const;
362
363  /// Enable tracking of recently allocated nodes for potential reclamation
364  /// when calling reclaimRecentlyAllocatedNodes().
365  void enableNodeReclamation() { reclaimNodes = true; }
366
367  /// Reclaim "uninteresting" nodes created since the last time this method
368  /// was called.
369  void reclaimRecentlyAllocatedNodes();
370};
371
372class ExplodedNodeSet {
373  typedef llvm::SmallPtrSet<ExplodedNode*,5> ImplTy;
374  ImplTy Impl;
375
376public:
377  ExplodedNodeSet(ExplodedNode *N) {
378    assert (N && !static_cast<ExplodedNode*>(N)->isSink());
379    Impl.insert(N);
380  }
381
382  ExplodedNodeSet() {}
383
384  inline void Add(ExplodedNode *N) {
385    if (N && !static_cast<ExplodedNode*>(N)->isSink()) Impl.insert(N);
386  }
387
388  typedef ImplTy::iterator       iterator;
389  typedef ImplTy::const_iterator const_iterator;
390
391  unsigned size() const { return Impl.size();  }
392  bool empty()    const { return Impl.empty(); }
393  bool erase(ExplodedNode *N) { return Impl.erase(N); }
394
395  void clear() { Impl.clear(); }
396  void insert(const ExplodedNodeSet &S) {
397    assert(&S != this);
398    if (empty())
399      Impl = S.Impl;
400    else
401      Impl.insert(S.begin(), S.end());
402  }
403
404  inline iterator begin() { return Impl.begin(); }
405  inline iterator end()   { return Impl.end();   }
406
407  inline const_iterator begin() const { return Impl.begin(); }
408  inline const_iterator end()   const { return Impl.end();   }
409};
410
411} // end GR namespace
412
413} // end clang namespace
414
415// GraphTraits
416
417namespace llvm {
418  template<> struct GraphTraits<clang::ento::ExplodedNode*> {
419    typedef clang::ento::ExplodedNode NodeType;
420    typedef NodeType::succ_iterator  ChildIteratorType;
421    typedef llvm::df_iterator<NodeType*>      nodes_iterator;
422
423    static inline NodeType* getEntryNode(NodeType* N) {
424      return N;
425    }
426
427    static inline ChildIteratorType child_begin(NodeType* N) {
428      return N->succ_begin();
429    }
430
431    static inline ChildIteratorType child_end(NodeType* N) {
432      return N->succ_end();
433    }
434
435    static inline nodes_iterator nodes_begin(NodeType* N) {
436      return df_begin(N);
437    }
438
439    static inline nodes_iterator nodes_end(NodeType* N) {
440      return df_end(N);
441    }
442  };
443
444  template<> struct GraphTraits<const clang::ento::ExplodedNode*> {
445    typedef const clang::ento::ExplodedNode NodeType;
446    typedef NodeType::const_succ_iterator   ChildIteratorType;
447    typedef llvm::df_iterator<NodeType*>       nodes_iterator;
448
449    static inline NodeType* getEntryNode(NodeType* N) {
450      return N;
451    }
452
453    static inline ChildIteratorType child_begin(NodeType* N) {
454      return N->succ_begin();
455    }
456
457    static inline ChildIteratorType child_end(NodeType* N) {
458      return N->succ_end();
459    }
460
461    static inline nodes_iterator nodes_begin(NodeType* N) {
462      return df_begin(N);
463    }
464
465    static inline nodes_iterator nodes_end(NodeType* N) {
466      return df_end(N);
467    }
468  };
469
470} // end llvm namespace
471
472#endif
473