ExplodedGraph.h revision b9b0f6fb6e113b5e6be3ed9754c4bf01186a17bf 
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    const_cast<ProgramState*>(State)->incrementReferenceCount();
123    if (IsSink)
124      Succs.setFlag();
125  }
126
127  ~ExplodedNode() {
128    const_cast<ProgramState*>(State)->decrementReferenceCount();
129  }
130
131  /// getLocation - Returns the edge associated with the given node.
132  ProgramPoint getLocation() const { return Location; }
133
134  const LocationContext *getLocationContext() const {
135    return getLocation().getLocationContext();
136  }
137
138  const Decl &getCodeDecl() const { return *getLocationContext()->getDecl(); }
139
140  CFG &getCFG() const { return *getLocationContext()->getCFG(); }
141
142  ParentMap &getParentMap() const {return getLocationContext()->getParentMap();}
143
144  template <typename T>
145  T &getAnalysis() const {
146    return *getLocationContext()->getAnalysis<T>();
147  }
148
149  ProgramStateRef getState() const { return State; }
150
151  template <typename T>
152  const T* getLocationAs() const { return llvm::dyn_cast<T>(&Location); }
153
154  static void Profile(llvm::FoldingSetNodeID &ID,
155                      const ProgramPoint &Loc,
156                      ProgramStateRef state,
157                      bool IsSink) {
158    ID.Add(Loc);
159    ID.AddPointer(state);
160    ID.AddBoolean(IsSink);
161  }
162
163  void Profile(llvm::FoldingSetNodeID& ID) const {
164    Profile(ID, getLocation(), getState(), isSink());
165  }
166
167  /// addPredeccessor - Adds a predecessor to the current node, and
168  ///  in tandem add this node as a successor of the other node.
169  void addPredecessor(ExplodedNode *V, ExplodedGraph &G);
170
171  unsigned succ_size() const { return Succs.size(); }
172  unsigned pred_size() const { return Preds.size(); }
173  bool succ_empty() const { return Succs.empty(); }
174  bool pred_empty() const { return Preds.empty(); }
175
176  bool isSink() const { return Succs.getFlag(); }
177
178  ExplodedNode *getFirstPred() {
179    return pred_empty() ? NULL : *(pred_begin());
180  }
181
182  const ExplodedNode *getFirstPred() const {
183    return const_cast<ExplodedNode*>(this)->getFirstPred();
184  }
185
186  // Iterators over successor and predecessor vertices.
187  typedef ExplodedNode**       succ_iterator;
188  typedef const ExplodedNode* const * const_succ_iterator;
189  typedef ExplodedNode**       pred_iterator;
190  typedef const ExplodedNode* const * const_pred_iterator;
191
192  pred_iterator pred_begin() { return Preds.begin(); }
193  pred_iterator pred_end() { return Preds.end(); }
194
195  const_pred_iterator pred_begin() const {
196    return const_cast<ExplodedNode*>(this)->pred_begin();
197  }
198  const_pred_iterator pred_end() const {
199    return const_cast<ExplodedNode*>(this)->pred_end();
200  }
201
202  succ_iterator succ_begin() { return Succs.begin(); }
203  succ_iterator succ_end() { return Succs.end(); }
204
205  const_succ_iterator succ_begin() const {
206    return const_cast<ExplodedNode*>(this)->succ_begin();
207  }
208  const_succ_iterator succ_end() const {
209    return const_cast<ExplodedNode*>(this)->succ_end();
210  }
211
212  // For debugging.
213
214public:
215
216  class Auditor {
217  public:
218    virtual ~Auditor();
219    virtual void AddEdge(ExplodedNode *Src, ExplodedNode *Dst) = 0;
220  };
221
222  static void SetAuditor(Auditor* A);
223
224private:
225  void replaceSuccessor(ExplodedNode *node) { Succs.replaceNode(node); }
226  void replacePredecessor(ExplodedNode *node) { Preds.replaceNode(node); }
227};
228
229// FIXME: Is this class necessary?
230class InterExplodedGraphMap {
231  virtual void anchor();
232  llvm::DenseMap<const ExplodedNode*, ExplodedNode*> M;
233  friend class ExplodedGraph;
234
235public:
236  ExplodedNode *getMappedNode(const ExplodedNode *N) const;
237
238  InterExplodedGraphMap() {}
239  virtual ~InterExplodedGraphMap() {}
240};
241
242class ExplodedGraph {
243protected:
244  friend class CoreEngine;
245
246  // Type definitions.
247  typedef SmallVector<ExplodedNode*,2>    RootsTy;
248  typedef SmallVector<ExplodedNode*,10>   EndNodesTy;
249
250  /// Roots - The roots of the simulation graph. Usually there will be only
251  /// one, but clients are free to establish multiple subgraphs within a single
252  /// SimulGraph. Moreover, these subgraphs can often merge when paths from
253  /// different roots reach the same state at the same program location.
254  RootsTy Roots;
255
256  /// EndNodes - The nodes in the simulation graph which have been
257  ///  specially marked as the endpoint of an abstract simulation path.
258  EndNodesTy EndNodes;
259
260  /// Nodes - The nodes in the graph.
261  llvm::FoldingSet<ExplodedNode> Nodes;
262
263  /// BVC - Allocator and context for allocating nodes and their predecessor
264  /// and successor groups.
265  BumpVectorContext BVC;
266
267  /// NumNodes - The number of nodes in the graph.
268  unsigned NumNodes;
269
270  /// A list of recently allocated nodes that can potentially be recycled.
271  void *recentlyAllocatedNodes;
272
273  /// A list of nodes that can be reused.
274  void *freeNodes;
275
276  /// A flag that indicates whether nodes should be recycled.
277  bool reclaimNodes;
278
279  /// Counter to determine when to reclaim nodes.
280  unsigned reclaimCounter;
281
282public:
283
284  /// \brief Retrieve the node associated with a (Location,State) pair,
285  ///  where the 'Location' is a ProgramPoint in the CFG.  If no node for
286  ///  this pair exists, it is created. IsNew is set to true if
287  ///  the node was freshly created.
288  ExplodedNode *getNode(const ProgramPoint &L, ProgramStateRef State,
289                        bool IsSink = false,
290                        bool* IsNew = 0);
291
292  ExplodedGraph* MakeEmptyGraph() const {
293    return new ExplodedGraph();
294  }
295
296  /// addRoot - Add an untyped node to the set of roots.
297  ExplodedNode *addRoot(ExplodedNode *V) {
298    Roots.push_back(V);
299    return V;
300  }
301
302  /// addEndOfPath - Add an untyped node to the set of EOP nodes.
303  ExplodedNode *addEndOfPath(ExplodedNode *V) {
304    EndNodes.push_back(V);
305    return V;
306  }
307
308  ExplodedGraph();
309
310  ~ExplodedGraph();
311
312  unsigned num_roots() const { return Roots.size(); }
313  unsigned num_eops() const { return EndNodes.size(); }
314
315  bool empty() const { return NumNodes == 0; }
316  unsigned size() const { return NumNodes; }
317
318  // Iterators.
319  typedef ExplodedNode                        NodeTy;
320  typedef llvm::FoldingSet<ExplodedNode>      AllNodesTy;
321  typedef NodeTy**                            roots_iterator;
322  typedef NodeTy* const *                     const_roots_iterator;
323  typedef NodeTy**                            eop_iterator;
324  typedef NodeTy* const *                     const_eop_iterator;
325  typedef AllNodesTy::iterator                node_iterator;
326  typedef AllNodesTy::const_iterator          const_node_iterator;
327
328  node_iterator nodes_begin() { return Nodes.begin(); }
329
330  node_iterator nodes_end() { return Nodes.end(); }
331
332  const_node_iterator nodes_begin() const { return Nodes.begin(); }
333
334  const_node_iterator nodes_end() const { return Nodes.end(); }
335
336  roots_iterator roots_begin() { return Roots.begin(); }
337
338  roots_iterator roots_end() { return Roots.end(); }
339
340  const_roots_iterator roots_begin() const { return Roots.begin(); }
341
342  const_roots_iterator roots_end() const { return Roots.end(); }
343
344  eop_iterator eop_begin() { return EndNodes.begin(); }
345
346  eop_iterator eop_end() { return EndNodes.end(); }
347
348  const_eop_iterator eop_begin() const { return EndNodes.begin(); }
349
350  const_eop_iterator eop_end() const { return EndNodes.end(); }
351
352  llvm::BumpPtrAllocator & getAllocator() { return BVC.getAllocator(); }
353  BumpVectorContext &getNodeAllocator() { return BVC; }
354
355  typedef llvm::DenseMap<const ExplodedNode*, ExplodedNode*> NodeMap;
356
357  std::pair<ExplodedGraph*, InterExplodedGraphMap*>
358  Trim(const NodeTy* const* NBeg, const NodeTy* const* NEnd,
359       llvm::DenseMap<const void*, const void*> *InverseMap = 0) const;
360
361  ExplodedGraph* TrimInternal(const ExplodedNode* const * NBeg,
362                              const ExplodedNode* const * NEnd,
363                              InterExplodedGraphMap *M,
364                    llvm::DenseMap<const void*, const void*> *InverseMap) const;
365
366  /// Enable tracking of recently allocated nodes for potential reclamation
367  /// when calling reclaimRecentlyAllocatedNodes().
368  void enableNodeReclamation() { reclaimNodes = true; }
369
370  /// Reclaim "uninteresting" nodes created since the last time this method
371  /// was called.
372  void reclaimRecentlyAllocatedNodes();
373
374private:
375  bool shouldCollect(const ExplodedNode *node);
376  void collectNode(ExplodedNode *node);
377};
378
379class ExplodedNodeSet {
380  typedef llvm::SmallPtrSet<ExplodedNode*,5> ImplTy;
381  ImplTy Impl;
382
383public:
384  ExplodedNodeSet(ExplodedNode *N) {
385    assert (N && !static_cast<ExplodedNode*>(N)->isSink());
386    Impl.insert(N);
387  }
388
389  ExplodedNodeSet() {}
390
391  inline void Add(ExplodedNode *N) {
392    if (N && !static_cast<ExplodedNode*>(N)->isSink()) Impl.insert(N);
393  }
394
395  typedef ImplTy::iterator       iterator;
396  typedef ImplTy::const_iterator const_iterator;
397
398  unsigned size() const { return Impl.size();  }
399  bool empty()    const { return Impl.empty(); }
400  bool erase(ExplodedNode *N) { return Impl.erase(N); }
401
402  void clear() { Impl.clear(); }
403  void insert(const ExplodedNodeSet &S) {
404    assert(&S != this);
405    if (empty())
406      Impl = S.Impl;
407    else
408      Impl.insert(S.begin(), S.end());
409  }
410
411  inline iterator begin() { return Impl.begin(); }
412  inline iterator end()   { return Impl.end();   }
413
414  inline const_iterator begin() const { return Impl.begin(); }
415  inline const_iterator end()   const { return Impl.end();   }
416};
417
418} // end GR namespace
419
420} // end clang namespace
421
422// GraphTraits
423
424namespace llvm {
425  template<> struct GraphTraits<clang::ento::ExplodedNode*> {
426    typedef clang::ento::ExplodedNode NodeType;
427    typedef NodeType::succ_iterator  ChildIteratorType;
428    typedef llvm::df_iterator<NodeType*>      nodes_iterator;
429
430    static inline NodeType* getEntryNode(NodeType* N) {
431      return N;
432    }
433
434    static inline ChildIteratorType child_begin(NodeType* N) {
435      return N->succ_begin();
436    }
437
438    static inline ChildIteratorType child_end(NodeType* N) {
439      return N->succ_end();
440    }
441
442    static inline nodes_iterator nodes_begin(NodeType* N) {
443      return df_begin(N);
444    }
445
446    static inline nodes_iterator nodes_end(NodeType* N) {
447      return df_end(N);
448    }
449  };
450
451  template<> struct GraphTraits<const clang::ento::ExplodedNode*> {
452    typedef const clang::ento::ExplodedNode NodeType;
453    typedef NodeType::const_succ_iterator   ChildIteratorType;
454    typedef llvm::df_iterator<NodeType*>       nodes_iterator;
455
456    static inline NodeType* getEntryNode(NodeType* N) {
457      return N;
458    }
459
460    static inline ChildIteratorType child_begin(NodeType* N) {
461      return N->succ_begin();
462    }
463
464    static inline ChildIteratorType child_end(NodeType* N) {
465      return N->succ_end();
466    }
467
468    static inline nodes_iterator nodes_begin(NodeType* N) {
469      return df_begin(N);
470    }
471
472    static inline nodes_iterator nodes_end(NodeType* N) {
473      return df_end(N);
474    }
475  };
476
477} // end llvm namespace
478
479#endif
480