ExplodedGraph.h revision 626719bd2c09e27fe7c182724a812d27f59e3819 
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#include <vector>
36
37namespace clang {
38
39class CFG;
40
41namespace ento {
42
43class ExplodedGraph;
44
45//===----------------------------------------------------------------------===//
46// ExplodedGraph "implementation" classes.  These classes are not typed to
47// contain a specific kind of state.  Typed-specialized versions are defined
48// on top of these classes.
49//===----------------------------------------------------------------------===//
50
51// ExplodedNode is not constified all over the engine because we need to add
52// successors to it at any time after creating it.
53
54class ExplodedNode : public llvm::FoldingSetNode {
55  friend class ExplodedGraph;
56  friend class CoreEngine;
57  friend class NodeBuilder;
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  ProgramStateRef 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, ProgramStateRef state,
121                        bool IsSink)
122    : Location(loc), State(state) {
123    if (IsSink)
124      Succs.setFlag();
125  }
126
127  ~ExplodedNode() {}
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  ProgramStateRef 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,
154                      ProgramStateRef state,
155                      bool IsSink) {
156    ID.Add(Loc);
157    ID.AddPointer(state.getPtr());
158    ID.AddBoolean(IsSink);
159  }
160
161  void Profile(llvm::FoldingSetNodeID& ID) const {
162    Profile(ID, getLocation(), getState(), isSink());
163  }
164
165  /// addPredeccessor - Adds a predecessor to the current node, and
166  ///  in tandem add this node as a successor of the other node.
167  void addPredecessor(ExplodedNode *V, ExplodedGraph &G);
168
169  unsigned succ_size() const { return Succs.size(); }
170  unsigned pred_size() const { return Preds.size(); }
171  bool succ_empty() const { return Succs.empty(); }
172  bool pred_empty() const { return Preds.empty(); }
173
174  bool isSink() const { return Succs.getFlag(); }
175
176  ExplodedNode *getFirstPred() {
177    return pred_empty() ? NULL : *(pred_begin());
178  }
179
180  const ExplodedNode *getFirstPred() const {
181    return const_cast<ExplodedNode*>(this)->getFirstPred();
182  }
183
184  // Iterators over successor and predecessor vertices.
185  typedef ExplodedNode**       succ_iterator;
186  typedef const ExplodedNode* const * const_succ_iterator;
187  typedef ExplodedNode**       pred_iterator;
188  typedef const ExplodedNode* const * const_pred_iterator;
189
190  pred_iterator pred_begin() { return Preds.begin(); }
191  pred_iterator pred_end() { return Preds.end(); }
192
193  const_pred_iterator pred_begin() const {
194    return const_cast<ExplodedNode*>(this)->pred_begin();
195  }
196  const_pred_iterator pred_end() const {
197    return const_cast<ExplodedNode*>(this)->pred_end();
198  }
199
200  succ_iterator succ_begin() { return Succs.begin(); }
201  succ_iterator succ_end() { return Succs.end(); }
202
203  const_succ_iterator succ_begin() const {
204    return const_cast<ExplodedNode*>(this)->succ_begin();
205  }
206  const_succ_iterator succ_end() const {
207    return const_cast<ExplodedNode*>(this)->succ_end();
208  }
209
210  // For debugging.
211
212public:
213
214  class Auditor {
215  public:
216    virtual ~Auditor();
217    virtual void AddEdge(ExplodedNode *Src, ExplodedNode *Dst) = 0;
218  };
219
220  static void SetAuditor(Auditor* A);
221
222private:
223  void replaceSuccessor(ExplodedNode *node) { Succs.replaceNode(node); }
224  void replacePredecessor(ExplodedNode *node) { Preds.replaceNode(node); }
225};
226
227// FIXME: Is this class necessary?
228class InterExplodedGraphMap {
229  virtual void anchor();
230  llvm::DenseMap<const ExplodedNode*, ExplodedNode*> M;
231  friend class ExplodedGraph;
232
233public:
234  ExplodedNode *getMappedNode(const ExplodedNode *N) const;
235
236  InterExplodedGraphMap() {}
237  virtual ~InterExplodedGraphMap() {}
238};
239
240class ExplodedGraph {
241protected:
242  friend class CoreEngine;
243
244  // Type definitions.
245  typedef std::vector<ExplodedNode *> NodeVector;
246
247  /// 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  NodeVector Roots;
252
253  /// The nodes in the simulation graph which have been
254  /// specially marked as the endpoint of an abstract simulation path.
255  NodeVector 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  NodeVector ChangedNodes;
269
270  /// A list of nodes that can be reused.
271  NodeVector 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 NodeVector::iterator                roots_iterator;
319  typedef NodeVector::const_iterator          const_roots_iterator;
320  typedef NodeVector::iterator                eop_iterator;
321  typedef NodeVector::const_iterator          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
371private:
372  bool shouldCollect(const ExplodedNode *node);
373  void collectNode(ExplodedNode *node);
374};
375
376class ExplodedNodeSet {
377  typedef llvm::SmallPtrSet<ExplodedNode*,5> ImplTy;
378  ImplTy Impl;
379
380public:
381  ExplodedNodeSet(ExplodedNode *N) {
382    assert (N && !static_cast<ExplodedNode*>(N)->isSink());
383    Impl.insert(N);
384  }
385
386  ExplodedNodeSet() {}
387
388  inline void Add(ExplodedNode *N) {
389    if (N && !static_cast<ExplodedNode*>(N)->isSink()) Impl.insert(N);
390  }
391
392  typedef ImplTy::iterator       iterator;
393  typedef ImplTy::const_iterator const_iterator;
394
395  unsigned size() const { return Impl.size();  }
396  bool empty()    const { return Impl.empty(); }
397  bool erase(ExplodedNode *N) { return Impl.erase(N); }
398
399  void clear() { Impl.clear(); }
400  void insert(const ExplodedNodeSet &S) {
401    assert(&S != this);
402    if (empty())
403      Impl = S.Impl;
404    else
405      Impl.insert(S.begin(), S.end());
406  }
407
408  inline iterator begin() { return Impl.begin(); }
409  inline iterator end()   { return Impl.end();   }
410
411  inline const_iterator begin() const { return Impl.begin(); }
412  inline const_iterator end()   const { return Impl.end();   }
413};
414
415} // end GR namespace
416
417} // end clang namespace
418
419// GraphTraits
420
421namespace llvm {
422  template<> struct GraphTraits<clang::ento::ExplodedNode*> {
423    typedef clang::ento::ExplodedNode NodeType;
424    typedef NodeType::succ_iterator  ChildIteratorType;
425    typedef llvm::df_iterator<NodeType*>      nodes_iterator;
426
427    static inline NodeType* getEntryNode(NodeType* N) {
428      return N;
429    }
430
431    static inline ChildIteratorType child_begin(NodeType* N) {
432      return N->succ_begin();
433    }
434
435    static inline ChildIteratorType child_end(NodeType* N) {
436      return N->succ_end();
437    }
438
439    static inline nodes_iterator nodes_begin(NodeType* N) {
440      return df_begin(N);
441    }
442
443    static inline nodes_iterator nodes_end(NodeType* N) {
444      return df_end(N);
445    }
446  };
447
448  template<> struct GraphTraits<const clang::ento::ExplodedNode*> {
449    typedef const clang::ento::ExplodedNode NodeType;
450    typedef NodeType::const_succ_iterator   ChildIteratorType;
451    typedef llvm::df_iterator<NodeType*>       nodes_iterator;
452
453    static inline NodeType* getEntryNode(NodeType* N) {
454      return N;
455    }
456
457    static inline ChildIteratorType child_begin(NodeType* N) {
458      return N->succ_begin();
459    }
460
461    static inline ChildIteratorType child_end(NodeType* N) {
462      return N->succ_end();
463    }
464
465    static inline nodes_iterator nodes_begin(NodeType* N) {
466      return df_begin(N);
467    }
468
469    static inline nodes_iterator nodes_end(NodeType* N) {
470      return df_end(N);
471    }
472  };
473
474} // end llvm namespace
475
476#endif
477