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_STATICANALYZER_CORE_PATHSENSITIVE_EXPLODEDGRAPH_H 20 #define LLVM_CLANG_STATICANALYZER_CORE_PATHSENSITIVE_EXPLODEDGRAPH_H 21 22 #include "clang/AST/Decl.h" 23 #include "clang/Analysis/AnalysisContext.h" 24 #include "clang/Analysis/ProgramPoint.h" 25 #include "clang/Analysis/Support/BumpVector.h" 26 #include "clang/StaticAnalyzer/Core/PathSensitive/ProgramState.h" 27 #include "llvm/ADT/DepthFirstIterator.h" 28 #include "llvm/ADT/FoldingSet.h" 29 #include "llvm/ADT/GraphTraits.h" 30 #include "llvm/ADT/SmallPtrSet.h" 31 #include "llvm/ADT/SmallVector.h" 32 #include "llvm/Support/Allocator.h" 33 #include "llvm/Support/Casting.h" 34 #include <memory> 35 #include <utility> 36 #include <vector> 37 38 namespace clang { 39 40 class CFG; 41 42 namespace ento { 43 44 class 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 55 class 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 /// Efficiently stores a list of ExplodedNodes, or an optional flag. 65 /// 66 /// NodeGroup provides opaque storage for a list of ExplodedNodes, optimizing 67 /// for the case when there is only one node in the group. This is a fairly 68 /// common case in an ExplodedGraph, where most nodes have only one 69 /// predecessor and many have only one successor. It can also be used to 70 /// store a flag rather than a node list, which ExplodedNode uses to mark 71 /// whether a node is a sink. If the flag is set, the group is implicitly 72 /// empty and no nodes may be added. 73 class NodeGroup { 74 // Conceptually a discriminated union. If the low bit is set, the node is 75 // a sink. If the low bit is not set, the pointer refers to the storage 76 // for the nodes in the group. 77 // This is not a PointerIntPair in order to keep the storage type opaque. 78 uintptr_t P; 79 80 public: P(Flag)81 NodeGroup(bool Flag = false) : P(Flag) { 82 assert(getFlag() == Flag); 83 } 84 85 ExplodedNode * const *begin() const; 86 87 ExplodedNode * const *end() const; 88 89 unsigned size() const; 90 empty()91 bool empty() const { return P == 0 || getFlag() != 0; } 92 93 /// Adds a node to the list. 94 /// 95 /// The group must not have been created with its flag set. 96 void addNode(ExplodedNode *N, ExplodedGraph &G); 97 98 /// Replaces the single node in this group with a new node. 99 /// 100 /// Note that this should only be used when you know the group was not 101 /// created with its flag set, and that the group is empty or contains 102 /// only a single node. 103 void replaceNode(ExplodedNode *node); 104 105 /// Returns whether this group was created with its flag set. getFlag()106 bool getFlag() const { 107 return (P & 1); 108 } 109 }; 110 111 /// Location - The program location (within a function body) associated 112 /// with this node. 113 const ProgramPoint Location; 114 115 /// State - The state associated with this node. 116 ProgramStateRef State; 117 118 /// Preds - The predecessors of this node. 119 NodeGroup Preds; 120 121 /// Succs - The successors of this node. 122 NodeGroup Succs; 123 124 public: ExplodedNode(const ProgramPoint & loc,ProgramStateRef state,bool IsSink)125 explicit ExplodedNode(const ProgramPoint &loc, ProgramStateRef state, 126 bool IsSink) 127 : Location(loc), State(std::move(state)), Succs(IsSink) { 128 assert(isSink() == IsSink); 129 } 130 131 /// getLocation - Returns the edge associated with the given node. getLocation()132 ProgramPoint getLocation() const { return Location; } 133 getLocationContext()134 const LocationContext *getLocationContext() const { 135 return getLocation().getLocationContext(); 136 } 137 getStackFrame()138 const StackFrameContext *getStackFrame() const { 139 return getLocationContext()->getCurrentStackFrame(); 140 } 141 getCodeDecl()142 const Decl &getCodeDecl() const { return *getLocationContext()->getDecl(); } 143 getCFG()144 CFG &getCFG() const { return *getLocationContext()->getCFG(); } 145 getParentMap()146 ParentMap &getParentMap() const {return getLocationContext()->getParentMap();} 147 148 template <typename T> getAnalysis()149 T &getAnalysis() const { 150 return *getLocationContext()->getAnalysis<T>(); 151 } 152 getState()153 const ProgramStateRef &getState() const { return State; } 154 155 template <typename T> getLocationAs()156 Optional<T> getLocationAs() const LLVM_LVALUE_FUNCTION { 157 return Location.getAs<T>(); 158 } 159 Profile(llvm::FoldingSetNodeID & ID,const ProgramPoint & Loc,const ProgramStateRef & state,bool IsSink)160 static void Profile(llvm::FoldingSetNodeID &ID, 161 const ProgramPoint &Loc, 162 const ProgramStateRef &state, 163 bool IsSink) { 164 ID.Add(Loc); 165 ID.AddPointer(state.get()); 166 ID.AddBoolean(IsSink); 167 } 168 Profile(llvm::FoldingSetNodeID & ID)169 void Profile(llvm::FoldingSetNodeID& ID) const { 170 // We avoid copy constructors by not using accessors. 171 Profile(ID, Location, State, isSink()); 172 } 173 174 /// addPredeccessor - Adds a predecessor to the current node, and 175 /// in tandem add this node as a successor of the other node. 176 void addPredecessor(ExplodedNode *V, ExplodedGraph &G); 177 succ_size()178 unsigned succ_size() const { return Succs.size(); } pred_size()179 unsigned pred_size() const { return Preds.size(); } succ_empty()180 bool succ_empty() const { return Succs.empty(); } pred_empty()181 bool pred_empty() const { return Preds.empty(); } 182 isSink()183 bool isSink() const { return Succs.getFlag(); } 184 hasSinglePred()185 bool hasSinglePred() const { 186 return (pred_size() == 1); 187 } 188 getFirstPred()189 ExplodedNode *getFirstPred() { 190 return pred_empty() ? nullptr : *(pred_begin()); 191 } 192 getFirstPred()193 const ExplodedNode *getFirstPred() const { 194 return const_cast<ExplodedNode*>(this)->getFirstPred(); 195 } 196 getFirstSucc()197 const ExplodedNode *getFirstSucc() const { 198 return succ_empty() ? nullptr : *(succ_begin()); 199 } 200 201 // Iterators over successor and predecessor vertices. 202 typedef ExplodedNode* const * succ_iterator; 203 typedef const ExplodedNode* const * const_succ_iterator; 204 typedef ExplodedNode* const * pred_iterator; 205 typedef const ExplodedNode* const * const_pred_iterator; 206 pred_begin()207 pred_iterator pred_begin() { return Preds.begin(); } pred_end()208 pred_iterator pred_end() { return Preds.end(); } 209 pred_begin()210 const_pred_iterator pred_begin() const { 211 return const_cast<ExplodedNode*>(this)->pred_begin(); 212 } pred_end()213 const_pred_iterator pred_end() const { 214 return const_cast<ExplodedNode*>(this)->pred_end(); 215 } 216 succ_begin()217 succ_iterator succ_begin() { return Succs.begin(); } succ_end()218 succ_iterator succ_end() { return Succs.end(); } 219 succ_begin()220 const_succ_iterator succ_begin() const { 221 return const_cast<ExplodedNode*>(this)->succ_begin(); 222 } succ_end()223 const_succ_iterator succ_end() const { 224 return const_cast<ExplodedNode*>(this)->succ_end(); 225 } 226 227 // For debugging. 228 229 public: 230 231 class Auditor { 232 public: 233 virtual ~Auditor(); 234 virtual void AddEdge(ExplodedNode *Src, ExplodedNode *Dst) = 0; 235 }; 236 237 static void SetAuditor(Auditor* A); 238 239 private: replaceSuccessor(ExplodedNode * node)240 void replaceSuccessor(ExplodedNode *node) { Succs.replaceNode(node); } replacePredecessor(ExplodedNode * node)241 void replacePredecessor(ExplodedNode *node) { Preds.replaceNode(node); } 242 }; 243 244 typedef llvm::DenseMap<const ExplodedNode *, const ExplodedNode *> 245 InterExplodedGraphMap; 246 247 class ExplodedGraph { 248 protected: 249 friend class CoreEngine; 250 251 // Type definitions. 252 typedef std::vector<ExplodedNode *> NodeVector; 253 254 /// The roots of the simulation graph. Usually there will be only 255 /// one, but clients are free to establish multiple subgraphs within a single 256 /// SimulGraph. Moreover, these subgraphs can often merge when paths from 257 /// different roots reach the same state at the same program location. 258 NodeVector Roots; 259 260 /// The nodes in the simulation graph which have been 261 /// specially marked as the endpoint of an abstract simulation path. 262 NodeVector EndNodes; 263 264 /// Nodes - The nodes in the graph. 265 llvm::FoldingSet<ExplodedNode> Nodes; 266 267 /// BVC - Allocator and context for allocating nodes and their predecessor 268 /// and successor groups. 269 BumpVectorContext BVC; 270 271 /// NumNodes - The number of nodes in the graph. 272 unsigned NumNodes; 273 274 /// A list of recently allocated nodes that can potentially be recycled. 275 NodeVector ChangedNodes; 276 277 /// A list of nodes that can be reused. 278 NodeVector FreeNodes; 279 280 /// Determines how often nodes are reclaimed. 281 /// 282 /// If this is 0, nodes will never be reclaimed. 283 unsigned ReclaimNodeInterval; 284 285 /// Counter to determine when to reclaim nodes. 286 unsigned ReclaimCounter; 287 288 public: 289 290 /// \brief Retrieve the node associated with a (Location,State) pair, 291 /// where the 'Location' is a ProgramPoint in the CFG. If no node for 292 /// this pair exists, it is created. IsNew is set to true if 293 /// the node was freshly created. 294 ExplodedNode *getNode(const ProgramPoint &L, ProgramStateRef State, 295 bool IsSink = false, 296 bool* IsNew = nullptr); 297 298 /// \brief Create a node for a (Location, State) pair, 299 /// but don't store it for deduplication later. This 300 /// is useful when copying an already completed 301 /// ExplodedGraph for further processing. 302 ExplodedNode *createUncachedNode(const ProgramPoint &L, 303 ProgramStateRef State, 304 bool IsSink = false); 305 MakeEmptyGraph()306 std::unique_ptr<ExplodedGraph> MakeEmptyGraph() const { 307 return llvm::make_unique<ExplodedGraph>(); 308 } 309 310 /// addRoot - Add an untyped node to the set of roots. addRoot(ExplodedNode * V)311 ExplodedNode *addRoot(ExplodedNode *V) { 312 Roots.push_back(V); 313 return V; 314 } 315 316 /// addEndOfPath - Add an untyped node to the set of EOP nodes. addEndOfPath(ExplodedNode * V)317 ExplodedNode *addEndOfPath(ExplodedNode *V) { 318 EndNodes.push_back(V); 319 return V; 320 } 321 322 ExplodedGraph(); 323 324 ~ExplodedGraph(); 325 num_roots()326 unsigned num_roots() const { return Roots.size(); } num_eops()327 unsigned num_eops() const { return EndNodes.size(); } 328 empty()329 bool empty() const { return NumNodes == 0; } size()330 unsigned size() const { return NumNodes; } 331 reserve(unsigned NodeCount)332 void reserve(unsigned NodeCount) { Nodes.reserve(NodeCount); } 333 334 // Iterators. 335 typedef ExplodedNode NodeTy; 336 typedef llvm::FoldingSet<ExplodedNode> AllNodesTy; 337 typedef NodeVector::iterator roots_iterator; 338 typedef NodeVector::const_iterator const_roots_iterator; 339 typedef NodeVector::iterator eop_iterator; 340 typedef NodeVector::const_iterator const_eop_iterator; 341 typedef AllNodesTy::iterator node_iterator; 342 typedef AllNodesTy::const_iterator const_node_iterator; 343 nodes_begin()344 node_iterator nodes_begin() { return Nodes.begin(); } 345 nodes_end()346 node_iterator nodes_end() { return Nodes.end(); } 347 nodes_begin()348 const_node_iterator nodes_begin() const { return Nodes.begin(); } 349 nodes_end()350 const_node_iterator nodes_end() const { return Nodes.end(); } 351 roots_begin()352 roots_iterator roots_begin() { return Roots.begin(); } 353 roots_end()354 roots_iterator roots_end() { return Roots.end(); } 355 roots_begin()356 const_roots_iterator roots_begin() const { return Roots.begin(); } 357 roots_end()358 const_roots_iterator roots_end() const { return Roots.end(); } 359 eop_begin()360 eop_iterator eop_begin() { return EndNodes.begin(); } 361 eop_end()362 eop_iterator eop_end() { return EndNodes.end(); } 363 eop_begin()364 const_eop_iterator eop_begin() const { return EndNodes.begin(); } 365 eop_end()366 const_eop_iterator eop_end() const { return EndNodes.end(); } 367 getAllocator()368 llvm::BumpPtrAllocator & getAllocator() { return BVC.getAllocator(); } getNodeAllocator()369 BumpVectorContext &getNodeAllocator() { return BVC; } 370 371 typedef llvm::DenseMap<const ExplodedNode*, ExplodedNode*> NodeMap; 372 373 /// Creates a trimmed version of the graph that only contains paths leading 374 /// to the given nodes. 375 /// 376 /// \param Nodes The nodes which must appear in the final graph. Presumably 377 /// these are end-of-path nodes (i.e. they have no successors). 378 /// \param[out] ForwardMap A optional map from nodes in this graph to nodes in 379 /// the returned graph. 380 /// \param[out] InverseMap An optional map from nodes in the returned graph to 381 /// nodes in this graph. 382 /// \returns The trimmed graph 383 std::unique_ptr<ExplodedGraph> 384 trim(ArrayRef<const NodeTy *> Nodes, 385 InterExplodedGraphMap *ForwardMap = nullptr, 386 InterExplodedGraphMap *InverseMap = nullptr) const; 387 388 /// Enable tracking of recently allocated nodes for potential reclamation 389 /// when calling reclaimRecentlyAllocatedNodes(). enableNodeReclamation(unsigned Interval)390 void enableNodeReclamation(unsigned Interval) { 391 ReclaimCounter = ReclaimNodeInterval = Interval; 392 } 393 394 /// Reclaim "uninteresting" nodes created since the last time this method 395 /// was called. 396 void reclaimRecentlyAllocatedNodes(); 397 398 /// \brief Returns true if nodes for the given expression kind are always 399 /// kept around. 400 static bool isInterestingLValueExpr(const Expr *Ex); 401 402 private: 403 bool shouldCollect(const ExplodedNode *node); 404 void collectNode(ExplodedNode *node); 405 }; 406 407 class ExplodedNodeSet { 408 typedef llvm::SmallPtrSet<ExplodedNode*,5> ImplTy; 409 ImplTy Impl; 410 411 public: ExplodedNodeSet(ExplodedNode * N)412 ExplodedNodeSet(ExplodedNode *N) { 413 assert (N && !static_cast<ExplodedNode*>(N)->isSink()); 414 Impl.insert(N); 415 } 416 ExplodedNodeSet()417 ExplodedNodeSet() {} 418 Add(ExplodedNode * N)419 inline void Add(ExplodedNode *N) { 420 if (N && !static_cast<ExplodedNode*>(N)->isSink()) Impl.insert(N); 421 } 422 423 typedef ImplTy::iterator iterator; 424 typedef ImplTy::const_iterator const_iterator; 425 size()426 unsigned size() const { return Impl.size(); } empty()427 bool empty() const { return Impl.empty(); } erase(ExplodedNode * N)428 bool erase(ExplodedNode *N) { return Impl.erase(N); } 429 clear()430 void clear() { Impl.clear(); } insert(const ExplodedNodeSet & S)431 void insert(const ExplodedNodeSet &S) { 432 assert(&S != this); 433 if (empty()) 434 Impl = S.Impl; 435 else 436 Impl.insert(S.begin(), S.end()); 437 } 438 begin()439 inline iterator begin() { return Impl.begin(); } end()440 inline iterator end() { return Impl.end(); } 441 begin()442 inline const_iterator begin() const { return Impl.begin(); } end()443 inline const_iterator end() const { return Impl.end(); } 444 }; 445 446 } // end GR namespace 447 448 } // end clang namespace 449 450 // GraphTraits 451 452 namespace llvm { 453 template<> struct GraphTraits<clang::ento::ExplodedNode*> { 454 typedef clang::ento::ExplodedNode NodeType; 455 typedef NodeType::succ_iterator ChildIteratorType; 456 typedef llvm::df_iterator<NodeType*> nodes_iterator; 457 458 static inline NodeType* getEntryNode(NodeType* N) { 459 return N; 460 } 461 462 static inline ChildIteratorType child_begin(NodeType* N) { 463 return N->succ_begin(); 464 } 465 466 static inline ChildIteratorType child_end(NodeType* N) { 467 return N->succ_end(); 468 } 469 470 static inline nodes_iterator nodes_begin(NodeType* N) { 471 return df_begin(N); 472 } 473 474 static inline nodes_iterator nodes_end(NodeType* N) { 475 return df_end(N); 476 } 477 }; 478 479 template<> struct GraphTraits<const clang::ento::ExplodedNode*> { 480 typedef const clang::ento::ExplodedNode NodeType; 481 typedef NodeType::const_succ_iterator ChildIteratorType; 482 typedef llvm::df_iterator<NodeType*> nodes_iterator; 483 484 static inline NodeType* getEntryNode(NodeType* N) { 485 return N; 486 } 487 488 static inline ChildIteratorType child_begin(NodeType* N) { 489 return N->succ_begin(); 490 } 491 492 static inline ChildIteratorType child_end(NodeType* N) { 493 return N->succ_end(); 494 } 495 496 static inline nodes_iterator nodes_begin(NodeType* N) { 497 return df_begin(N); 498 } 499 500 static inline nodes_iterator nodes_end(NodeType* N) { 501 return df_end(N); 502 } 503 }; 504 505 } // end llvm namespace 506 507 #endif 508