ExplodedGraph.h revision 683b70c70dc47532af1215e4b1566de9d47a3be5
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 /// Efficiently stores a list of ExplodedNodes, or an optional flag. 64 /// 65 /// NodeGroup provides opaque storage for a list of ExplodedNodes, optimizing 66 /// for the case when there is only one node in the group. This is a fairly 67 /// common case in an ExplodedGraph, where most nodes have only one 68 /// predecessor and many have only one successor. It can also be used to 69 /// store a flag rather than a node list, which ExplodedNode uses to mark 70 /// whether a node is a sink. If the flag is set, the group is implicitly 71 /// empty and no nodes may be added. 72 class NodeGroup { 73 // Conceptually a discriminated union. If the low bit is set, the node is 74 // a sink. If the low bit is not set, the pointer refers to the storage 75 // for the nodes in the group. 76 // This is not a PointerIntPair in order to keep the storage type opaque. 77 uintptr_t P; 78 79 public: 80 NodeGroup(bool Flag = false) : P(Flag) { 81 assert(getFlag() == Flag); 82 } 83 84 ExplodedNode * const *begin() const; 85 86 ExplodedNode * const *end() const; 87 88 unsigned size() const; 89 90 bool empty() const { return P == 0 || getFlag() != 0; } 91 92 /// Adds a node to the list. 93 /// 94 /// The group must not have been created with its flag set. 95 void addNode(ExplodedNode *N, ExplodedGraph &G); 96 97 /// Replaces the single node in this group with a new node. 98 /// 99 /// Note that this should only be used when you know the group was not 100 /// created with its flag set, and that the group is empty or contains 101 /// only a single node. 102 void replaceNode(ExplodedNode *node); 103 104 /// Returns whether this group was created with its flag set. 105 bool getFlag() const { 106 return (P & 1); 107 } 108 }; 109 110 /// Location - The program location (within a function body) associated 111 /// with this node. 112 const ProgramPoint Location; 113 114 /// State - The state associated with this node. 115 ProgramStateRef State; 116 117 /// Preds - The predecessors of this node. 118 NodeGroup Preds; 119 120 /// Succs - The successors of this node. 121 NodeGroup Succs; 122 123public: 124 125 explicit ExplodedNode(const ProgramPoint &loc, ProgramStateRef state, 126 bool IsSink) 127 : Location(loc), State(state), Succs(IsSink) { 128 assert(isSink() == IsSink); 129 } 130 131 ~ExplodedNode() {} 132 133 /// getLocation - Returns the edge associated with the given node. 134 ProgramPoint getLocation() const { return Location; } 135 136 const LocationContext *getLocationContext() const { 137 return getLocation().getLocationContext(); 138 } 139 140 const StackFrameContext *getStackFrame() const { 141 return getLocationContext()->getCurrentStackFrame(); 142 } 143 144 const Decl &getCodeDecl() const { return *getLocationContext()->getDecl(); } 145 146 CFG &getCFG() const { return *getLocationContext()->getCFG(); } 147 148 ParentMap &getParentMap() const {return getLocationContext()->getParentMap();} 149 150 template <typename T> 151 T &getAnalysis() const { 152 return *getLocationContext()->getAnalysis<T>(); 153 } 154 155 ProgramStateRef getState() const { return State; } 156 157 template <typename T> 158 const T* getLocationAs() const LLVM_LVALUE_FUNCTION { 159 return dyn_cast<T>(&Location); 160 } 161 162#if LLVM_HAS_RVALUE_REFERENCE_THIS 163 template <typename T> 164 void getLocationAs() && LLVM_DELETED_FUNCTION; 165#endif 166 167 static void Profile(llvm::FoldingSetNodeID &ID, 168 const ProgramPoint &Loc, 169 const ProgramStateRef &state, 170 bool IsSink) { 171 ID.Add(Loc); 172 ID.AddPointer(state.getPtr()); 173 ID.AddBoolean(IsSink); 174 } 175 176 void Profile(llvm::FoldingSetNodeID& ID) const { 177 Profile(ID, getLocation(), getState(), isSink()); 178 } 179 180 /// addPredeccessor - Adds a predecessor to the current node, and 181 /// in tandem add this node as a successor of the other node. 182 void addPredecessor(ExplodedNode *V, ExplodedGraph &G); 183 184 unsigned succ_size() const { return Succs.size(); } 185 unsigned pred_size() const { return Preds.size(); } 186 bool succ_empty() const { return Succs.empty(); } 187 bool pred_empty() const { return Preds.empty(); } 188 189 bool isSink() const { return Succs.getFlag(); } 190 191 bool hasSinglePred() const { 192 return (pred_size() == 1); 193 } 194 195 ExplodedNode *getFirstPred() { 196 return pred_empty() ? NULL : *(pred_begin()); 197 } 198 199 const ExplodedNode *getFirstPred() const { 200 return const_cast<ExplodedNode*>(this)->getFirstPred(); 201 } 202 203 // Iterators over successor and predecessor vertices. 204 typedef ExplodedNode* const * succ_iterator; 205 typedef const ExplodedNode* const * const_succ_iterator; 206 typedef ExplodedNode* const * pred_iterator; 207 typedef const ExplodedNode* const * const_pred_iterator; 208 209 pred_iterator pred_begin() { return Preds.begin(); } 210 pred_iterator pred_end() { return Preds.end(); } 211 212 const_pred_iterator pred_begin() const { 213 return const_cast<ExplodedNode*>(this)->pred_begin(); 214 } 215 const_pred_iterator pred_end() const { 216 return const_cast<ExplodedNode*>(this)->pred_end(); 217 } 218 219 succ_iterator succ_begin() { return Succs.begin(); } 220 succ_iterator succ_end() { return Succs.end(); } 221 222 const_succ_iterator succ_begin() const { 223 return const_cast<ExplodedNode*>(this)->succ_begin(); 224 } 225 const_succ_iterator succ_end() const { 226 return const_cast<ExplodedNode*>(this)->succ_end(); 227 } 228 229 // For debugging. 230 231public: 232 233 class Auditor { 234 public: 235 virtual ~Auditor(); 236 virtual void AddEdge(ExplodedNode *Src, ExplodedNode *Dst) = 0; 237 }; 238 239 static void SetAuditor(Auditor* A); 240 241private: 242 void replaceSuccessor(ExplodedNode *node) { Succs.replaceNode(node); } 243 void replacePredecessor(ExplodedNode *node) { Preds.replaceNode(node); } 244}; 245 246// FIXME: Is this class necessary? 247class InterExplodedGraphMap { 248 virtual void anchor(); 249 llvm::DenseMap<const ExplodedNode*, ExplodedNode*> M; 250 friend class ExplodedGraph; 251 252public: 253 ExplodedNode *getMappedNode(const ExplodedNode *N) const; 254 255 InterExplodedGraphMap() {} 256 virtual ~InterExplodedGraphMap() {} 257}; 258 259class ExplodedGraph { 260protected: 261 friend class CoreEngine; 262 263 // Type definitions. 264 typedef std::vector<ExplodedNode *> NodeVector; 265 266 /// The roots of the simulation graph. Usually there will be only 267 /// one, but clients are free to establish multiple subgraphs within a single 268 /// SimulGraph. Moreover, these subgraphs can often merge when paths from 269 /// different roots reach the same state at the same program location. 270 NodeVector Roots; 271 272 /// The nodes in the simulation graph which have been 273 /// specially marked as the endpoint of an abstract simulation path. 274 NodeVector EndNodes; 275 276 /// Nodes - The nodes in the graph. 277 llvm::FoldingSet<ExplodedNode> Nodes; 278 279 /// BVC - Allocator and context for allocating nodes and their predecessor 280 /// and successor groups. 281 BumpVectorContext BVC; 282 283 /// NumNodes - The number of nodes in the graph. 284 unsigned NumNodes; 285 286 /// A list of recently allocated nodes that can potentially be recycled. 287 NodeVector ChangedNodes; 288 289 /// A list of nodes that can be reused. 290 NodeVector FreeNodes; 291 292 /// Determines how often nodes are reclaimed. 293 /// 294 /// If this is 0, nodes will never be reclaimed. 295 unsigned ReclaimNodeInterval; 296 297 /// Counter to determine when to reclaim nodes. 298 unsigned ReclaimCounter; 299 300public: 301 302 /// \brief Retrieve the node associated with a (Location,State) pair, 303 /// where the 'Location' is a ProgramPoint in the CFG. If no node for 304 /// this pair exists, it is created. IsNew is set to true if 305 /// the node was freshly created. 306 ExplodedNode *getNode(const ProgramPoint &L, ProgramStateRef State, 307 bool IsSink = false, 308 bool* IsNew = 0); 309 310 ExplodedGraph* MakeEmptyGraph() const { 311 return new ExplodedGraph(); 312 } 313 314 /// addRoot - Add an untyped node to the set of roots. 315 ExplodedNode *addRoot(ExplodedNode *V) { 316 Roots.push_back(V); 317 return V; 318 } 319 320 /// addEndOfPath - Add an untyped node to the set of EOP nodes. 321 ExplodedNode *addEndOfPath(ExplodedNode *V) { 322 EndNodes.push_back(V); 323 return V; 324 } 325 326 ExplodedGraph(); 327 328 ~ExplodedGraph(); 329 330 unsigned num_roots() const { return Roots.size(); } 331 unsigned num_eops() const { return EndNodes.size(); } 332 333 bool empty() const { return NumNodes == 0; } 334 unsigned size() const { return NumNodes; } 335 336 // Iterators. 337 typedef ExplodedNode NodeTy; 338 typedef llvm::FoldingSet<ExplodedNode> AllNodesTy; 339 typedef NodeVector::iterator roots_iterator; 340 typedef NodeVector::const_iterator const_roots_iterator; 341 typedef NodeVector::iterator eop_iterator; 342 typedef NodeVector::const_iterator const_eop_iterator; 343 typedef AllNodesTy::iterator node_iterator; 344 typedef AllNodesTy::const_iterator const_node_iterator; 345 346 node_iterator nodes_begin() { return Nodes.begin(); } 347 348 node_iterator nodes_end() { return Nodes.end(); } 349 350 const_node_iterator nodes_begin() const { return Nodes.begin(); } 351 352 const_node_iterator nodes_end() const { return Nodes.end(); } 353 354 roots_iterator roots_begin() { return Roots.begin(); } 355 356 roots_iterator roots_end() { return Roots.end(); } 357 358 const_roots_iterator roots_begin() const { return Roots.begin(); } 359 360 const_roots_iterator roots_end() const { return Roots.end(); } 361 362 eop_iterator eop_begin() { return EndNodes.begin(); } 363 364 eop_iterator eop_end() { return EndNodes.end(); } 365 366 const_eop_iterator eop_begin() const { return EndNodes.begin(); } 367 368 const_eop_iterator eop_end() const { return EndNodes.end(); } 369 370 llvm::BumpPtrAllocator & getAllocator() { return BVC.getAllocator(); } 371 BumpVectorContext &getNodeAllocator() { return BVC; } 372 373 typedef llvm::DenseMap<const ExplodedNode*, ExplodedNode*> NodeMap; 374 375 std::pair<ExplodedGraph*, InterExplodedGraphMap*> 376 Trim(const NodeTy* const* NBeg, const NodeTy* const* NEnd, 377 llvm::DenseMap<const void*, const void*> *InverseMap = 0) const; 378 379 ExplodedGraph* TrimInternal(const ExplodedNode* const * NBeg, 380 const ExplodedNode* const * NEnd, 381 InterExplodedGraphMap *M, 382 llvm::DenseMap<const void*, const void*> *InverseMap) const; 383 384 /// Enable tracking of recently allocated nodes for potential reclamation 385 /// when calling reclaimRecentlyAllocatedNodes(). 386 void enableNodeReclamation(unsigned Interval) { 387 ReclaimCounter = ReclaimNodeInterval = Interval; 388 } 389 390 /// Reclaim "uninteresting" nodes created since the last time this method 391 /// was called. 392 void reclaimRecentlyAllocatedNodes(); 393 394private: 395 bool shouldCollect(const ExplodedNode *node); 396 void collectNode(ExplodedNode *node); 397}; 398 399class ExplodedNodeSet { 400 typedef llvm::SmallPtrSet<ExplodedNode*,5> ImplTy; 401 ImplTy Impl; 402 403public: 404 ExplodedNodeSet(ExplodedNode *N) { 405 assert (N && !static_cast<ExplodedNode*>(N)->isSink()); 406 Impl.insert(N); 407 } 408 409 ExplodedNodeSet() {} 410 411 inline void Add(ExplodedNode *N) { 412 if (N && !static_cast<ExplodedNode*>(N)->isSink()) Impl.insert(N); 413 } 414 415 typedef ImplTy::iterator iterator; 416 typedef ImplTy::const_iterator const_iterator; 417 418 unsigned size() const { return Impl.size(); } 419 bool empty() const { return Impl.empty(); } 420 bool erase(ExplodedNode *N) { return Impl.erase(N); } 421 422 void clear() { Impl.clear(); } 423 void insert(const ExplodedNodeSet &S) { 424 assert(&S != this); 425 if (empty()) 426 Impl = S.Impl; 427 else 428 Impl.insert(S.begin(), S.end()); 429 } 430 431 inline iterator begin() { return Impl.begin(); } 432 inline iterator end() { return Impl.end(); } 433 434 inline const_iterator begin() const { return Impl.begin(); } 435 inline const_iterator end() const { return Impl.end(); } 436}; 437 438} // end GR namespace 439 440} // end clang namespace 441 442// GraphTraits 443 444namespace llvm { 445 template<> struct GraphTraits<clang::ento::ExplodedNode*> { 446 typedef clang::ento::ExplodedNode NodeType; 447 typedef NodeType::succ_iterator ChildIteratorType; 448 typedef llvm::df_iterator<NodeType*> nodes_iterator; 449 450 static inline NodeType* getEntryNode(NodeType* N) { 451 return N; 452 } 453 454 static inline ChildIteratorType child_begin(NodeType* N) { 455 return N->succ_begin(); 456 } 457 458 static inline ChildIteratorType child_end(NodeType* N) { 459 return N->succ_end(); 460 } 461 462 static inline nodes_iterator nodes_begin(NodeType* N) { 463 return df_begin(N); 464 } 465 466 static inline nodes_iterator nodes_end(NodeType* N) { 467 return df_end(N); 468 } 469 }; 470 471 template<> struct GraphTraits<const clang::ento::ExplodedNode*> { 472 typedef const clang::ento::ExplodedNode NodeType; 473 typedef NodeType::const_succ_iterator ChildIteratorType; 474 typedef llvm::df_iterator<NodeType*> nodes_iterator; 475 476 static inline NodeType* getEntryNode(NodeType* N) { 477 return N; 478 } 479 480 static inline ChildIteratorType child_begin(NodeType* N) { 481 return N->succ_begin(); 482 } 483 484 static inline ChildIteratorType child_end(NodeType* N) { 485 return N->succ_end(); 486 } 487 488 static inline nodes_iterator nodes_begin(NodeType* N) { 489 return df_begin(N); 490 } 491 492 static inline nodes_iterator nodes_end(NodeType* N) { 493 return df_end(N); 494 } 495 }; 496 497} // end llvm namespace 498 499#endif 500