ExplodedGraph.h revision 437ee81e54f39c2363d5fe0ea155604c28adc615 
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/ADT/DenseSet.h"
29#include "llvm/Support/Allocator.h"
30#include "llvm/ADT/OwningPtr.h"
31#include "llvm/ADT/GraphTraits.h"
32#include "llvm/ADT/DepthFirstIterator.h"
33#include "llvm/Support/Casting.h"
34#include "clang/Analysis/Support/BumpVector.h"
35#include "clang/StaticAnalyzer/Core/PathSensitive/ProgramState.h"
36#include <vector>
37
38namespace clang {
39
40class CFG;
41
42namespace ento {
43
44class ExplodedGraph;
45
46//===----------------------------------------------------------------------===//
47// ExplodedGraph "implementation" classes.  These classes are not typed to
48// contain a specific kind of state.  Typed-specialized versions are defined
49// on top of these classes.
50//===----------------------------------------------------------------------===//
51
52// ExplodedNode is not constified all over the engine because we need to add
53// successors to it at any time after creating it.
54
55class ExplodedNode : public llvm::FoldingSetNode {
56  friend class ExplodedGraph;
57  friend class CoreEngine;
58  friend class NodeBuilder;
59  friend class BranchNodeBuilder;
60  friend class IndirectGotoNodeBuilder;
61  friend class SwitchNodeBuilder;
62  friend class EndOfFunctionNodeBuilder;
63
64  class NodeGroup {
65    enum { Size1 = 0x0, SizeOther = 0x1, AuxFlag = 0x2, Mask = 0x3 };
66    uintptr_t P;
67
68    unsigned getKind() const {
69      return P & 0x1;
70    }
71
72    void *getPtr() const {
73      assert (!getFlag());
74      return reinterpret_cast<void*>(P & ~Mask);
75    }
76
77    ExplodedNode *getNode() const {
78      return reinterpret_cast<ExplodedNode*>(getPtr());
79    }
80
81  public:
82    NodeGroup() : P(0) {}
83
84    ExplodedNode **begin() const;
85
86    ExplodedNode **end() const;
87
88    unsigned size() const;
89
90    bool empty() const { return (P & ~Mask) == 0; }
91
92    void addNode(ExplodedNode *N, ExplodedGraph &G);
93
94    void replaceNode(ExplodedNode *node);
95
96    void setFlag() {
97      assert(P == 0);
98      P = AuxFlag;
99    }
100
101    bool getFlag() const {
102      return P & AuxFlag ? true : false;
103    }
104  };
105
106  /// Location - The program location (within a function body) associated
107  ///  with this node.
108  const ProgramPoint Location;
109
110  /// State - The state associated with this node.
111  ProgramStateRef State;
112
113  /// Preds - The predecessors of this node.
114  NodeGroup Preds;
115
116  /// Succs - The successors of this node.
117  NodeGroup Succs;
118
119public:
120
121  explicit ExplodedNode(const ProgramPoint &loc, ProgramStateRef state,
122                        bool IsSink)
123    : Location(loc), State(state) {
124    if (IsSink)
125      Succs.setFlag();
126  }
127
128  ~ExplodedNode() {}
129
130  /// getLocation - Returns the edge associated with the given node.
131  ProgramPoint getLocation() const { return Location; }
132
133  const LocationContext *getLocationContext() const {
134    return getLocation().getLocationContext();
135  }
136
137  const Decl &getCodeDecl() const { return *getLocationContext()->getDecl(); }
138
139  CFG &getCFG() const { return *getLocationContext()->getCFG(); }
140
141  ParentMap &getParentMap() const {return getLocationContext()->getParentMap();}
142
143  template <typename T>
144  T &getAnalysis() const {
145    return *getLocationContext()->getAnalysis<T>();
146  }
147
148  ProgramStateRef getState() const { return State; }
149
150  template <typename T>
151  const T* getLocationAs() const { return llvm::dyn_cast<T>(&Location); }
152
153  static void Profile(llvm::FoldingSetNodeID &ID,
154                      const ProgramPoint &Loc,
155                      ProgramStateRef state,
156                      bool IsSink) {
157    ID.Add(Loc);
158    ID.AddPointer(state.getPtr());
159    ID.AddBoolean(IsSink);
160  }
161
162  void Profile(llvm::FoldingSetNodeID& ID) const {
163    Profile(ID, getLocation(), getState(), isSink());
164  }
165
166  /// addPredeccessor - Adds a predecessor to the current node, and
167  ///  in tandem add this node as a successor of the other node.
168  void addPredecessor(ExplodedNode *V, ExplodedGraph &G);
169
170  unsigned succ_size() const { return Succs.size(); }
171  unsigned pred_size() const { return Preds.size(); }
172  bool succ_empty() const { return Succs.empty(); }
173  bool pred_empty() const { return Preds.empty(); }
174
175  bool isSink() const { return Succs.getFlag(); }
176
177  ExplodedNode *getFirstPred() {
178    return pred_empty() ? NULL : *(pred_begin());
179  }
180
181  const ExplodedNode *getFirstPred() const {
182    return const_cast<ExplodedNode*>(this)->getFirstPred();
183  }
184
185  // Iterators over successor and predecessor vertices.
186  typedef ExplodedNode**       succ_iterator;
187  typedef const ExplodedNode* const * const_succ_iterator;
188  typedef ExplodedNode**       pred_iterator;
189  typedef const ExplodedNode* const * const_pred_iterator;
190
191  pred_iterator pred_begin() { return Preds.begin(); }
192  pred_iterator pred_end() { return Preds.end(); }
193
194  const_pred_iterator pred_begin() const {
195    return const_cast<ExplodedNode*>(this)->pred_begin();
196  }
197  const_pred_iterator pred_end() const {
198    return const_cast<ExplodedNode*>(this)->pred_end();
199  }
200
201  succ_iterator succ_begin() { return Succs.begin(); }
202  succ_iterator succ_end() { return Succs.end(); }
203
204  const_succ_iterator succ_begin() const {
205    return const_cast<ExplodedNode*>(this)->succ_begin();
206  }
207  const_succ_iterator succ_end() const {
208    return const_cast<ExplodedNode*>(this)->succ_end();
209  }
210
211  // For debugging.
212
213public:
214
215  class Auditor {
216  public:
217    virtual ~Auditor();
218    virtual void AddEdge(ExplodedNode *Src, ExplodedNode *Dst) = 0;
219  };
220
221  static void SetAuditor(Auditor* A);
222
223private:
224  void replaceSuccessor(ExplodedNode *node) { Succs.replaceNode(node); }
225  void replacePredecessor(ExplodedNode *node) { Preds.replaceNode(node); }
226};
227
228// FIXME: Is this class necessary?
229class InterExplodedGraphMap {
230  virtual void anchor();
231  llvm::DenseMap<const ExplodedNode*, ExplodedNode*> M;
232  friend class ExplodedGraph;
233
234public:
235  ExplodedNode *getMappedNode(const ExplodedNode *N) const;
236
237  InterExplodedGraphMap() {}
238  virtual ~InterExplodedGraphMap() {}
239};
240
241class ExplodedGraph {
242protected:
243  friend class CoreEngine;
244  friend class ExplodedNode;
245
246  // Type definitions.
247  typedef std::vector<ExplodedNode *> NodeVector;
248
249  /// The roots of the simulation graph. Usually there will be only
250  /// one, but clients are free to establish multiple subgraphs within a single
251  /// SimulGraph. Moreover, these subgraphs can often merge when paths from
252  /// different roots reach the same state at the same program location.
253  NodeVector Roots;
254
255  /// The nodes in the simulation graph which have been
256  /// specially marked as the endpoint of an abstract simulation path.
257  NodeVector EndNodes;
258
259  /// Nodes - The nodes in the graph.
260  llvm::FoldingSet<ExplodedNode> Nodes;
261
262  /// BVC - Allocator and context for allocating nodes and their predecessor
263  /// and successor groups.
264  BumpVectorContext BVC;
265
266  /// NumNodes - The number of nodes in the graph.
267  unsigned NumNodes;
268
269  /// A list of recently allocated nodes that can potentially be recycled.
270  llvm::DenseSet<ExplodedNode*> ChangedNodes;
271
272  /// A list of nodes that can be reused.
273  NodeVector FreeNodes;
274
275  /// A flag that indicates whether nodes should be recycled.
276  bool reclaimNodes;
277
278public:
279
280  /// \brief Retrieve the node associated with a (Location,State) pair,
281  ///  where the 'Location' is a ProgramPoint in the CFG.  If no node for
282  ///  this pair exists, it is created. IsNew is set to true if
283  ///  the node was freshly created.
284  ExplodedNode *getNode(const ProgramPoint &L, ProgramStateRef State,
285                        bool IsSink = false,
286                        bool* IsNew = 0);
287
288  ExplodedGraph* MakeEmptyGraph() const {
289    return new ExplodedGraph();
290  }
291
292  /// addRoot - Add an untyped node to the set of roots.
293  ExplodedNode *addRoot(ExplodedNode *V) {
294    Roots.push_back(V);
295    return V;
296  }
297
298  /// addEndOfPath - Add an untyped node to the set of EOP nodes.
299  ExplodedNode *addEndOfPath(ExplodedNode *V) {
300    EndNodes.push_back(V);
301    return V;
302  }
303
304  ExplodedGraph();
305
306  ~ExplodedGraph();
307
308  unsigned num_roots() const { return Roots.size(); }
309  unsigned num_eops() const { return EndNodes.size(); }
310
311  bool empty() const { return NumNodes == 0; }
312  unsigned size() const { return NumNodes; }
313
314  // Iterators.
315  typedef ExplodedNode                        NodeTy;
316  typedef llvm::FoldingSet<ExplodedNode>      AllNodesTy;
317  typedef NodeVector::iterator                roots_iterator;
318  typedef NodeVector::const_iterator          const_roots_iterator;
319  typedef NodeVector::iterator                eop_iterator;
320  typedef NodeVector::const_iterator          const_eop_iterator;
321  typedef AllNodesTy::iterator                node_iterator;
322  typedef AllNodesTy::const_iterator          const_node_iterator;
323
324  node_iterator nodes_begin() { return Nodes.begin(); }
325
326  node_iterator nodes_end() { return Nodes.end(); }
327
328  const_node_iterator nodes_begin() const { return Nodes.begin(); }
329
330  const_node_iterator nodes_end() const { return Nodes.end(); }
331
332  roots_iterator roots_begin() { return Roots.begin(); }
333
334  roots_iterator roots_end() { return Roots.end(); }
335
336  const_roots_iterator roots_begin() const { return Roots.begin(); }
337
338  const_roots_iterator roots_end() const { return Roots.end(); }
339
340  eop_iterator eop_begin() { return EndNodes.begin(); }
341
342  eop_iterator eop_end() { return EndNodes.end(); }
343
344  const_eop_iterator eop_begin() const { return EndNodes.begin(); }
345
346  const_eop_iterator eop_end() const { return EndNodes.end(); }
347
348  llvm::BumpPtrAllocator & getAllocator() { return BVC.getAllocator(); }
349  BumpVectorContext &getNodeAllocator() { return BVC; }
350
351  typedef llvm::DenseMap<const ExplodedNode*, ExplodedNode*> NodeMap;
352
353  std::pair<ExplodedGraph*, InterExplodedGraphMap*>
354  Trim(const NodeTy* const* NBeg, const NodeTy* const* NEnd,
355       llvm::DenseMap<const void*, const void*> *InverseMap = 0) const;
356
357  ExplodedGraph* TrimInternal(const ExplodedNode* const * NBeg,
358                              const ExplodedNode* const * NEnd,
359                              InterExplodedGraphMap *M,
360                    llvm::DenseMap<const void*, const void*> *InverseMap) const;
361
362  /// Enable tracking of recently allocated nodes for potential reclamation
363  /// when calling reclaimChangedNodes().
364  void enableNodeReclamation() { reclaimNodes = true; }
365
366  /// Reclaim "uninteresting" nodes created since the last time this method
367  /// was called.
368  void reclaimChangedNodes();
369
370private:
371  bool shouldCollect(const ExplodedNode *node);
372  void collectNode(ExplodedNode *node);
373};
374
375class ExplodedNodeSet {
376  typedef llvm::SmallPtrSet<ExplodedNode*,5> ImplTy;
377  ImplTy Impl;
378
379public:
380  ExplodedNodeSet(ExplodedNode *N) {
381    assert (N && !static_cast<ExplodedNode*>(N)->isSink());
382    Impl.insert(N);
383  }
384
385  ExplodedNodeSet() {}
386
387  inline void Add(ExplodedNode *N) {
388    if (N && !static_cast<ExplodedNode*>(N)->isSink()) Impl.insert(N);
389  }
390
391  typedef ImplTy::iterator       iterator;
392  typedef ImplTy::const_iterator const_iterator;
393
394  unsigned size() const { return Impl.size();  }
395  bool empty()    const { return Impl.empty(); }
396  bool erase(ExplodedNode *N) { return Impl.erase(N); }
397
398  void clear() { Impl.clear(); }
399  void insert(const ExplodedNodeSet &S) {
400    assert(&S != this);
401    if (empty())
402      Impl = S.Impl;
403    else
404      Impl.insert(S.begin(), S.end());
405  }
406
407  inline iterator begin() { return Impl.begin(); }
408  inline iterator end()   { return Impl.end();   }
409
410  inline const_iterator begin() const { return Impl.begin(); }
411  inline const_iterator end()   const { return Impl.end();   }
412};
413
414} // end GR namespace
415
416} // end clang namespace
417
418// GraphTraits
419
420namespace llvm {
421  template<> struct GraphTraits<clang::ento::ExplodedNode*> {
422    typedef clang::ento::ExplodedNode NodeType;
423    typedef NodeType::succ_iterator  ChildIteratorType;
424    typedef llvm::df_iterator<NodeType*>      nodes_iterator;
425
426    static inline NodeType* getEntryNode(NodeType* N) {
427      return N;
428    }
429
430    static inline ChildIteratorType child_begin(NodeType* N) {
431      return N->succ_begin();
432    }
433
434    static inline ChildIteratorType child_end(NodeType* N) {
435      return N->succ_end();
436    }
437
438    static inline nodes_iterator nodes_begin(NodeType* N) {
439      return df_begin(N);
440    }
441
442    static inline nodes_iterator nodes_end(NodeType* N) {
443      return df_end(N);
444    }
445  };
446
447  template<> struct GraphTraits<const clang::ento::ExplodedNode*> {
448    typedef const clang::ento::ExplodedNode NodeType;
449    typedef NodeType::const_succ_iterator   ChildIteratorType;
450    typedef llvm::df_iterator<NodeType*>       nodes_iterator;
451
452    static inline NodeType* getEntryNode(NodeType* N) {
453      return N;
454    }
455
456    static inline ChildIteratorType child_begin(NodeType* N) {
457      return N->succ_begin();
458    }
459
460    static inline ChildIteratorType child_end(NodeType* N) {
461      return N->succ_end();
462    }
463
464    static inline nodes_iterator nodes_begin(NodeType* N) {
465      return df_begin(N);
466    }
467
468    static inline nodes_iterator nodes_end(NodeType* N) {
469      return df_end(N);
470    }
471  };
472
473} // end llvm namespace
474
475#endif
476