ExplodedGraph.h revision 309124
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 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 /// 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: 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 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. 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 124public: 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. 132 ProgramPoint getLocation() const { return Location; } 133 134 const LocationContext *getLocationContext() const { 135 return getLocation().getLocationContext(); 136 } 137 138 const StackFrameContext *getStackFrame() const { 139 return getLocationContext()->getCurrentStackFrame(); 140 } 141 142 const Decl &getCodeDecl() const { return *getLocationContext()->getDecl(); } 143 144 CFG &getCFG() const { return *getLocationContext()->getCFG(); } 145 146 ParentMap &getParentMap() const {return getLocationContext()->getParentMap();} 147 148 template <typename T> 149 T &getAnalysis() const { 150 return *getLocationContext()->getAnalysis<T>(); 151 } 152 153 const ProgramStateRef &getState() const { return State; } 154 155 template <typename T> 156 Optional<T> getLocationAs() const LLVM_LVALUE_FUNCTION { 157 return Location.getAs<T>(); 158 } 159 160 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 } 168 169 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); 177 178 unsigned succ_size() const { return Succs.size(); } 179 unsigned pred_size() const { return Preds.size(); } 180 bool succ_empty() const { return Succs.empty(); } 181 bool pred_empty() const { return Preds.empty(); } 182 183 bool isSink() const { return Succs.getFlag(); } 184 185 bool hasSinglePred() const { 186 return (pred_size() == 1); 187 } 188 189 ExplodedNode *getFirstPred() { 190 return pred_empty() ? nullptr : *(pred_begin()); 191 } 192 193 const ExplodedNode *getFirstPred() const { 194 return const_cast<ExplodedNode*>(this)->getFirstPred(); 195 } 196 197 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; 206 207 pred_iterator pred_begin() { return Preds.begin(); } 208 pred_iterator pred_end() { return Preds.end(); } 209 210 const_pred_iterator pred_begin() const { 211 return const_cast<ExplodedNode*>(this)->pred_begin(); 212 } 213 const_pred_iterator pred_end() const { 214 return const_cast<ExplodedNode*>(this)->pred_end(); 215 } 216 217 succ_iterator succ_begin() { return Succs.begin(); } 218 succ_iterator succ_end() { return Succs.end(); } 219 220 const_succ_iterator succ_begin() const { 221 return const_cast<ExplodedNode*>(this)->succ_begin(); 222 } 223 const_succ_iterator succ_end() const { 224 return const_cast<ExplodedNode*>(this)->succ_end(); 225 } 226 227 // For debugging. 228 229public: 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 239private: 240 void replaceSuccessor(ExplodedNode *node) { Succs.replaceNode(node); } 241 void replacePredecessor(ExplodedNode *node) { Preds.replaceNode(node); } 242}; 243 244typedef llvm::DenseMap<const ExplodedNode *, const ExplodedNode *> 245 InterExplodedGraphMap; 246 247class ExplodedGraph { 248protected: 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 288public: 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); 305 306 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. 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. 317 ExplodedNode *addEndOfPath(ExplodedNode *V) { 318 EndNodes.push_back(V); 319 return V; 320 } 321 322 ExplodedGraph(); 323 324 ~ExplodedGraph(); 325 326 unsigned num_roots() const { return Roots.size(); } 327 unsigned num_eops() const { return EndNodes.size(); } 328 329 bool empty() const { return NumNodes == 0; } 330 unsigned size() const { return NumNodes; } 331 332 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; 343 344 node_iterator nodes_begin() { return Nodes.begin(); } 345 346 node_iterator nodes_end() { return Nodes.end(); } 347 348 const_node_iterator nodes_begin() const { return Nodes.begin(); } 349 350 const_node_iterator nodes_end() const { return Nodes.end(); } 351 352 roots_iterator roots_begin() { return Roots.begin(); } 353 354 roots_iterator roots_end() { return Roots.end(); } 355 356 const_roots_iterator roots_begin() const { return Roots.begin(); } 357 358 const_roots_iterator roots_end() const { return Roots.end(); } 359 360 eop_iterator eop_begin() { return EndNodes.begin(); } 361 362 eop_iterator eop_end() { return EndNodes.end(); } 363 364 const_eop_iterator eop_begin() const { return EndNodes.begin(); } 365 366 const_eop_iterator eop_end() const { return EndNodes.end(); } 367 368 llvm::BumpPtrAllocator & getAllocator() { return BVC.getAllocator(); } 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(). 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 402private: 403 bool shouldCollect(const ExplodedNode *node); 404 void collectNode(ExplodedNode *node); 405}; 406 407class ExplodedNodeSet { 408 typedef llvm::SmallPtrSet<ExplodedNode*,5> ImplTy; 409 ImplTy Impl; 410 411public: 412 ExplodedNodeSet(ExplodedNode *N) { 413 assert (N && !static_cast<ExplodedNode*>(N)->isSink()); 414 Impl.insert(N); 415 } 416 417 ExplodedNodeSet() {} 418 419 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; 425 426 unsigned size() const { return Impl.size(); } 427 bool empty() const { return Impl.empty(); } 428 bool erase(ExplodedNode *N) { return Impl.erase(N); } 429 430 void clear() { Impl.clear(); } 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 } 438 439 inline iterator begin() { return Impl.begin(); } 440 inline iterator end() { return Impl.end(); } 441 442 inline const_iterator begin() const { return Impl.begin(); } 443 inline const_iterator end() const { return Impl.end(); } 444}; 445 446} // end GR namespace 447 448} // end clang namespace 449 450// GraphTraits 451 452namespace llvm { 453 template<> struct GraphTraits<clang::ento::ExplodedNode*> { 454 typedef clang::ento::ExplodedNode NodeType; 455 typedef clang::ento::ExplodedNode *NodeRef; 456 typedef NodeType::succ_iterator ChildIteratorType; 457 typedef llvm::df_iterator<NodeType*> nodes_iterator; 458 459 static inline NodeType* getEntryNode(NodeType* N) { 460 return N; 461 } 462 463 static inline ChildIteratorType child_begin(NodeType* N) { 464 return N->succ_begin(); 465 } 466 467 static inline ChildIteratorType child_end(NodeType* N) { 468 return N->succ_end(); 469 } 470 471 static inline nodes_iterator nodes_begin(NodeType* N) { 472 return df_begin(N); 473 } 474 475 static inline nodes_iterator nodes_end(NodeType* N) { 476 return df_end(N); 477 } 478 }; 479 480 template<> struct GraphTraits<const clang::ento::ExplodedNode*> { 481 typedef const clang::ento::ExplodedNode NodeType; 482 typedef const clang::ento::ExplodedNode *NodeRef; 483 typedef NodeType::const_succ_iterator ChildIteratorType; 484 typedef llvm::df_iterator<NodeType*> nodes_iterator; 485 486 static inline NodeType* getEntryNode(NodeType* N) { 487 return N; 488 } 489 490 static inline ChildIteratorType child_begin(NodeType* N) { 491 return N->succ_begin(); 492 } 493 494 static inline ChildIteratorType child_end(NodeType* N) { 495 return N->succ_end(); 496 } 497 498 static inline nodes_iterator nodes_begin(NodeType* N) { 499 return df_begin(N); 500 } 501 502 static inline nodes_iterator nodes_end(NodeType* N) { 503 return df_end(N); 504 } 505 }; 506 507} // end llvm namespace 508 509#endif 510