ExplodedGraph.h revision 686775deca8b8685eb90801495880e3abdd844c2 
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/GRState.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 StmtNodeBuilder;
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  const GRState* 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, const GRState* state)
120    : Location(loc), State(state) {
121    const_cast<GRState*>(State)->incrementReferenceCount();
122  }
123
124  ~ExplodedNode() {
125    const_cast<GRState*>(State)->decrementReferenceCount();
126  }
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  LiveVariables &getLiveVariables() const {
142    return *getLocationContext()->getLiveVariables();
143  }
144
145  const GRState* getState() const { return State; }
146
147  template <typename T>
148  const T* getLocationAs() const { return llvm::dyn_cast<T>(&Location); }
149
150  static void Profile(llvm::FoldingSetNodeID &ID,
151                      const ProgramPoint& Loc, const GRState* state) {
152    ID.Add(Loc);
153    ID.AddPointer(state);
154  }
155
156  void Profile(llvm::FoldingSetNodeID& ID) const {
157    Profile(ID, getLocation(), getState());
158  }
159
160  /// addPredeccessor - Adds a predecessor to the current node, and
161  ///  in tandem add this node as a successor of the other node.
162  void addPredecessor(ExplodedNode* V, ExplodedGraph &G);
163
164  unsigned succ_size() const { return Succs.size(); }
165  unsigned pred_size() const { return Preds.size(); }
166  bool succ_empty() const { return Succs.empty(); }
167  bool pred_empty() const { return Preds.empty(); }
168
169  bool isSink() const { return Succs.getFlag(); }
170  void markAsSink() { Succs.setFlag(); }
171
172  ExplodedNode* getFirstPred() {
173    return pred_empty() ? NULL : *(pred_begin());
174  }
175
176  const ExplodedNode* getFirstPred() const {
177    return const_cast<ExplodedNode*>(this)->getFirstPred();
178  }
179
180  // Iterators over successor and predecessor vertices.
181  typedef ExplodedNode**       succ_iterator;
182  typedef const ExplodedNode* const * const_succ_iterator;
183  typedef ExplodedNode**       pred_iterator;
184  typedef const ExplodedNode* const * const_pred_iterator;
185
186  pred_iterator pred_begin() { return Preds.begin(); }
187  pred_iterator pred_end() { return Preds.end(); }
188
189  const_pred_iterator pred_begin() const {
190    return const_cast<ExplodedNode*>(this)->pred_begin();
191  }
192  const_pred_iterator pred_end() const {
193    return const_cast<ExplodedNode*>(this)->pred_end();
194  }
195
196  succ_iterator succ_begin() { return Succs.begin(); }
197  succ_iterator succ_end() { return Succs.end(); }
198
199  const_succ_iterator succ_begin() const {
200    return const_cast<ExplodedNode*>(this)->succ_begin();
201  }
202  const_succ_iterator succ_end() const {
203    return const_cast<ExplodedNode*>(this)->succ_end();
204  }
205
206  // For debugging.
207
208public:
209
210  class Auditor {
211  public:
212    virtual ~Auditor();
213    virtual void AddEdge(ExplodedNode* Src, ExplodedNode* Dst) = 0;
214  };
215
216  static void SetAuditor(Auditor* A);
217
218private:
219  void replaceSuccessor(ExplodedNode *node) { Succs.replaceNode(node); }
220  void replacePredecessor(ExplodedNode *node) { Preds.replaceNode(node); }
221};
222
223// FIXME: Is this class necessary?
224class InterExplodedGraphMap {
225  llvm::DenseMap<const ExplodedNode*, ExplodedNode*> M;
226  friend class ExplodedGraph;
227
228public:
229  ExplodedNode* getMappedNode(const ExplodedNode* N) const;
230
231  InterExplodedGraphMap() {}
232  virtual ~InterExplodedGraphMap() {}
233};
234
235class ExplodedGraph {
236protected:
237  friend class CoreEngine;
238
239  // Type definitions.
240  typedef SmallVector<ExplodedNode*,2>    RootsTy;
241  typedef SmallVector<ExplodedNode*,10>   EndNodesTy;
242
243  /// Roots - The roots of the simulation graph. Usually there will be only
244  /// one, but clients are free to establish multiple subgraphs within a single
245  /// SimulGraph. Moreover, these subgraphs can often merge when paths from
246  /// different roots reach the same state at the same program location.
247  RootsTy Roots;
248
249  /// EndNodes - The nodes in the simulation graph which have been
250  ///  specially marked as the endpoint of an abstract simulation path.
251  EndNodesTy EndNodes;
252
253  /// Nodes - The nodes in the graph.
254  llvm::FoldingSet<ExplodedNode> Nodes;
255
256  /// BVC - Allocator and context for allocating nodes and their predecessor
257  /// and successor groups.
258  BumpVectorContext BVC;
259
260  /// NumNodes - The number of nodes in the graph.
261  unsigned NumNodes;
262
263  /// A list of recently allocated nodes that can potentially be recycled.
264  void *recentlyAllocatedNodes;
265
266  /// A list of nodes that can be reused.
267  void *freeNodes;
268
269  /// A flag that indicates whether nodes should be recycled.
270  bool reclaimNodes;
271
272public:
273  /// getNode - Retrieve the node associated with a (Location,State) pair,
274  ///  where the 'Location' is a ProgramPoint in the CFG.  If no node for
275  ///  this pair exists, it is created.  IsNew is set to true if
276  ///  the node was freshly created.
277
278  ExplodedNode* getNode(const ProgramPoint& L, const GRState *State,
279                        bool* IsNew = 0);
280
281  ExplodedGraph* MakeEmptyGraph() const {
282    return new ExplodedGraph();
283  }
284
285  /// addRoot - Add an untyped node to the set of roots.
286  ExplodedNode* addRoot(ExplodedNode* V) {
287    Roots.push_back(V);
288    return V;
289  }
290
291  /// addEndOfPath - Add an untyped node to the set of EOP nodes.
292  ExplodedNode* addEndOfPath(ExplodedNode* V) {
293    EndNodes.push_back(V);
294    return V;
295  }
296
297  ExplodedGraph()
298    : NumNodes(0), recentlyAllocatedNodes(0),
299      freeNodes(0), reclaimNodes(false) {}
300
301  ~ExplodedGraph();
302
303  unsigned num_roots() const { return Roots.size(); }
304  unsigned num_eops() const { return EndNodes.size(); }
305
306  bool empty() const { return NumNodes == 0; }
307  unsigned size() const { return NumNodes; }
308
309  // Iterators.
310  typedef ExplodedNode                        NodeTy;
311  typedef llvm::FoldingSet<ExplodedNode>      AllNodesTy;
312  typedef NodeTy**                            roots_iterator;
313  typedef NodeTy* const *                     const_roots_iterator;
314  typedef NodeTy**                            eop_iterator;
315  typedef NodeTy* const *                     const_eop_iterator;
316  typedef AllNodesTy::iterator                node_iterator;
317  typedef AllNodesTy::const_iterator          const_node_iterator;
318
319  node_iterator nodes_begin() { return Nodes.begin(); }
320
321  node_iterator nodes_end() { return Nodes.end(); }
322
323  const_node_iterator nodes_begin() const { return Nodes.begin(); }
324
325  const_node_iterator nodes_end() const { return Nodes.end(); }
326
327  roots_iterator roots_begin() { return Roots.begin(); }
328
329  roots_iterator roots_end() { return Roots.end(); }
330
331  const_roots_iterator roots_begin() const { return Roots.begin(); }
332
333  const_roots_iterator roots_end() const { return Roots.end(); }
334
335  eop_iterator eop_begin() { return EndNodes.begin(); }
336
337  eop_iterator eop_end() { return EndNodes.end(); }
338
339  const_eop_iterator eop_begin() const { return EndNodes.begin(); }
340
341  const_eop_iterator eop_end() const { return EndNodes.end(); }
342
343  llvm::BumpPtrAllocator & getAllocator() { return BVC.getAllocator(); }
344  BumpVectorContext &getNodeAllocator() { return BVC; }
345
346  typedef llvm::DenseMap<const ExplodedNode*, ExplodedNode*> NodeMap;
347
348  std::pair<ExplodedGraph*, InterExplodedGraphMap*>
349  Trim(const NodeTy* const* NBeg, const NodeTy* const* NEnd,
350       llvm::DenseMap<const void*, const void*> *InverseMap = 0) const;
351
352  ExplodedGraph* TrimInternal(const ExplodedNode* const * NBeg,
353                              const ExplodedNode* const * NEnd,
354                              InterExplodedGraphMap *M,
355                    llvm::DenseMap<const void*, const void*> *InverseMap) const;
356
357  /// Enable tracking of recently allocated nodes for potential reclamation
358  /// when calling reclaimRecentlyAllocatedNodes().
359  void enableNodeReclamation() { reclaimNodes = true; }
360
361  /// Reclaim "uninteresting" nodes created since the last time this method
362  /// was called.
363  void reclaimRecentlyAllocatedNodes();
364};
365
366class ExplodedNodeSet {
367  typedef llvm::SmallPtrSet<ExplodedNode*,5> ImplTy;
368  ImplTy Impl;
369
370public:
371  ExplodedNodeSet(ExplodedNode* N) {
372    assert (N && !static_cast<ExplodedNode*>(N)->isSink());
373    Impl.insert(N);
374  }
375
376  ExplodedNodeSet() {}
377
378  inline void Add(ExplodedNode* N) {
379    if (N && !static_cast<ExplodedNode*>(N)->isSink()) Impl.insert(N);
380  }
381
382  ExplodedNodeSet& operator=(const ExplodedNodeSet &X) {
383    Impl = X.Impl;
384    return *this;
385  }
386
387  typedef ImplTy::iterator       iterator;
388  typedef ImplTy::const_iterator const_iterator;
389
390  unsigned size() const { return Impl.size();  }
391  bool empty()    const { return Impl.empty(); }
392
393  void clear() { Impl.clear(); }
394  void insert(const ExplodedNodeSet &S) {
395    if (empty())
396      Impl = S.Impl;
397    else
398      Impl.insert(S.begin(), S.end());
399  }
400
401  inline iterator begin() { return Impl.begin(); }
402  inline iterator end()   { return Impl.end();   }
403
404  inline const_iterator begin() const { return Impl.begin(); }
405  inline const_iterator end()   const { return Impl.end();   }
406};
407
408} // end GR namespace
409
410} // end clang namespace
411
412// GraphTraits
413
414namespace llvm {
415  template<> struct GraphTraits<clang::ento::ExplodedNode*> {
416    typedef clang::ento::ExplodedNode NodeType;
417    typedef NodeType::succ_iterator  ChildIteratorType;
418    typedef llvm::df_iterator<NodeType*>      nodes_iterator;
419
420    static inline NodeType* getEntryNode(NodeType* N) {
421      return N;
422    }
423
424    static inline ChildIteratorType child_begin(NodeType* N) {
425      return N->succ_begin();
426    }
427
428    static inline ChildIteratorType child_end(NodeType* N) {
429      return N->succ_end();
430    }
431
432    static inline nodes_iterator nodes_begin(NodeType* N) {
433      return df_begin(N);
434    }
435
436    static inline nodes_iterator nodes_end(NodeType* N) {
437      return df_end(N);
438    }
439  };
440
441  template<> struct GraphTraits<const clang::ento::ExplodedNode*> {
442    typedef const clang::ento::ExplodedNode NodeType;
443    typedef NodeType::const_succ_iterator   ChildIteratorType;
444    typedef llvm::df_iterator<NodeType*>       nodes_iterator;
445
446    static inline NodeType* getEntryNode(NodeType* N) {
447      return N;
448    }
449
450    static inline ChildIteratorType child_begin(NodeType* N) {
451      return N->succ_begin();
452    }
453
454    static inline ChildIteratorType child_end(NodeType* N) {
455      return N->succ_end();
456    }
457
458    static inline nodes_iterator nodes_begin(NodeType* N) {
459      return df_begin(N);
460    }
461
462    static inline nodes_iterator nodes_end(NodeType* N) {
463      return df_end(N);
464    }
465  };
466
467} // end llvm namespace
468
469#endif
470