1 //===- Store.h - Interface for maps from Locations to Values ----*- C++ -*-===// 2 // 3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 4 // See https://llvm.org/LICENSE.txt for license information. 5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 6 // 7 //===----------------------------------------------------------------------===// 8 // 9 // This file defined the types Store and StoreManager. 10 // 11 //===----------------------------------------------------------------------===// 12 13 #ifndef LLVM_CLANG_STATICANALYZER_CORE_PATHSENSITIVE_STORE_H 14 #define LLVM_CLANG_STATICANALYZER_CORE_PATHSENSITIVE_STORE_H 15 16 #include "clang/AST/Type.h" 17 #include "clang/StaticAnalyzer/Core/PathSensitive/MemRegion.h" 18 #include "clang/StaticAnalyzer/Core/PathSensitive/ProgramState_Fwd.h" 19 #include "clang/StaticAnalyzer/Core/PathSensitive/SValBuilder.h" 20 #include "clang/StaticAnalyzer/Core/PathSensitive/SVals.h" 21 #include "clang/StaticAnalyzer/Core/PathSensitive/StoreRef.h" 22 #include "clang/StaticAnalyzer/Core/PathSensitive/SymExpr.h" 23 #include "clang/Basic/LLVM.h" 24 #include "llvm/ADT/ArrayRef.h" 25 #include "llvm/ADT/DenseSet.h" 26 #include "llvm/ADT/Optional.h" 27 #include "llvm/ADT/SmallVector.h" 28 #include <cassert> 29 #include <cstdint> 30 #include <memory> 31 32 namespace clang { 33 34 class ASTContext; 35 class CastExpr; 36 class CompoundLiteralExpr; 37 class CXXBasePath; 38 class Decl; 39 class Expr; 40 class LocationContext; 41 class ObjCIvarDecl; 42 class StackFrameContext; 43 44 namespace ento { 45 46 class CallEvent; 47 class ProgramStateManager; 48 class ScanReachableSymbols; 49 class SymbolReaper; 50 51 using InvalidatedSymbols = llvm::DenseSet<SymbolRef>; 52 53 class StoreManager { 54 protected: 55 SValBuilder &svalBuilder; 56 ProgramStateManager &StateMgr; 57 58 /// MRMgr - Manages region objects associated with this StoreManager. 59 MemRegionManager &MRMgr; 60 ASTContext &Ctx; 61 62 StoreManager(ProgramStateManager &stateMgr); 63 64 public: 65 virtual ~StoreManager() = default; 66 67 /// Return the value bound to specified location in a given state. 68 /// \param[in] store The store in which to make the lookup. 69 /// \param[in] loc The symbolic memory location. 70 /// \param[in] T An optional type that provides a hint indicating the 71 /// expected type of the returned value. This is used if the value is 72 /// lazily computed. 73 /// \return The value bound to the location \c loc. 74 virtual SVal getBinding(Store store, Loc loc, QualType T = QualType()) = 0; 75 76 /// Return the default value bound to a region in a given store. The default 77 /// binding is the value of sub-regions that were not initialized separately 78 /// from their base region. For example, if the structure is zero-initialized 79 /// upon construction, this method retrieves the concrete zero value, even if 80 /// some or all fields were later overwritten manually. Default binding may be 81 /// an unknown, undefined, concrete, or symbolic value. 82 /// \param[in] store The store in which to make the lookup. 83 /// \param[in] R The region to find the default binding for. 84 /// \return The default value bound to the region in the store, if a default 85 /// binding exists. 86 virtual Optional<SVal> getDefaultBinding(Store store, const MemRegion *R) = 0; 87 88 /// Return the default value bound to a LazyCompoundVal. The default binding 89 /// is used to represent the value of any fields or elements within the 90 /// structure represented by the LazyCompoundVal which were not initialized 91 /// explicitly separately from the whole structure. Default binding may be an 92 /// unknown, undefined, concrete, or symbolic value. 93 /// \param[in] lcv The lazy compound value. 94 /// \return The default value bound to the LazyCompoundVal \c lcv, if a 95 /// default binding exists. 96 Optional<SVal> getDefaultBinding(nonloc::LazyCompoundVal lcv) { 97 return getDefaultBinding(lcv.getStore(), lcv.getRegion()); 98 } 99 100 /// Return a store with the specified value bound to the given location. 101 /// \param[in] store The store in which to make the binding. 102 /// \param[in] loc The symbolic memory location. 103 /// \param[in] val The value to bind to location \c loc. 104 /// \return A StoreRef object that contains the same 105 /// bindings as \c store with the addition of having the value specified 106 /// by \c val bound to the location given for \c loc. 107 virtual StoreRef Bind(Store store, Loc loc, SVal val) = 0; 108 109 /// Return a store with the specified value bound to all sub-regions of the 110 /// region. The region must not have previous bindings. If you need to 111 /// invalidate existing bindings, consider invalidateRegions(). 112 virtual StoreRef BindDefaultInitial(Store store, const MemRegion *R, 113 SVal V) = 0; 114 115 /// Return a store with in which all values within the given region are 116 /// reset to zero. This method is allowed to overwrite previous bindings. 117 virtual StoreRef BindDefaultZero(Store store, const MemRegion *R) = 0; 118 119 /// Create a new store with the specified binding removed. 120 /// \param ST the original store, that is the basis for the new store. 121 /// \param L the location whose binding should be removed. 122 virtual StoreRef killBinding(Store ST, Loc L) = 0; 123 124 /// getInitialStore - Returns the initial "empty" store representing the 125 /// value bindings upon entry to an analyzed function. 126 virtual StoreRef getInitialStore(const LocationContext *InitLoc) = 0; 127 128 /// getRegionManager - Returns the internal RegionManager object that is 129 /// used to query and manipulate MemRegion objects. 130 MemRegionManager& getRegionManager() { return MRMgr; } 131 132 SValBuilder& getSValBuilder() { return svalBuilder; } 133 134 virtual Loc getLValueVar(const VarDecl *VD, const LocationContext *LC) { 135 return svalBuilder.makeLoc(MRMgr.getVarRegion(VD, LC)); 136 } 137 138 Loc getLValueCompoundLiteral(const CompoundLiteralExpr *CL, 139 const LocationContext *LC) { 140 return loc::MemRegionVal(MRMgr.getCompoundLiteralRegion(CL, LC)); 141 } 142 143 virtual SVal getLValueIvar(const ObjCIvarDecl *decl, SVal base); 144 145 virtual SVal getLValueField(const FieldDecl *D, SVal Base) { 146 return getLValueFieldOrIvar(D, Base); 147 } 148 149 virtual SVal getLValueElement(QualType elementType, NonLoc offset, SVal Base); 150 151 // FIXME: This should soon be eliminated altogether; clients should deal with 152 // region extents directly. 153 virtual DefinedOrUnknownSVal getSizeInElements(ProgramStateRef state, 154 const MemRegion *region, 155 QualType EleTy) { 156 return UnknownVal(); 157 } 158 159 /// ArrayToPointer - Used by ExprEngine::VistCast to handle implicit 160 /// conversions between arrays and pointers. 161 virtual SVal ArrayToPointer(Loc Array, QualType ElementTy) = 0; 162 163 /// Evaluates a chain of derived-to-base casts through the path specified in 164 /// \p Cast. 165 SVal evalDerivedToBase(SVal Derived, const CastExpr *Cast); 166 167 /// Evaluates a chain of derived-to-base casts through the specified path. 168 SVal evalDerivedToBase(SVal Derived, const CXXBasePath &CastPath); 169 170 /// Evaluates a derived-to-base cast through a single level of derivation. 171 SVal evalDerivedToBase(SVal Derived, QualType DerivedPtrType, 172 bool IsVirtual); 173 174 /// Attempts to do a down cast. Used to model BaseToDerived and C++ 175 /// dynamic_cast. 176 /// The callback may result in the following 3 scenarios: 177 /// - Successful cast (ex: derived is subclass of base). 178 /// - Failed cast (ex: derived is definitely not a subclass of base). 179 /// The distinction of this case from the next one is necessary to model 180 /// dynamic_cast. 181 /// - We don't know (base is a symbolic region and we don't have 182 /// enough info to determine if the cast will succeed at run time). 183 /// The function returns an SVal representing the derived class; it's 184 /// valid only if Failed flag is set to false. 185 SVal attemptDownCast(SVal Base, QualType DerivedPtrType, bool &Failed); 186 187 const ElementRegion *GetElementZeroRegion(const SubRegion *R, QualType T); 188 189 /// castRegion - Used by ExprEngine::VisitCast to handle casts from 190 /// a MemRegion* to a specific location type. 'R' is the region being 191 /// casted and 'CastToTy' the result type of the cast. 192 const MemRegion *castRegion(const MemRegion *region, QualType CastToTy); 193 194 virtual StoreRef removeDeadBindings(Store store, const StackFrameContext *LCtx, 195 SymbolReaper &SymReaper) = 0; 196 197 virtual bool includedInBindings(Store store, 198 const MemRegion *region) const = 0; 199 200 /// If the StoreManager supports it, increment the reference count of 201 /// the specified Store object. 202 virtual void incrementReferenceCount(Store store) {} 203 204 /// If the StoreManager supports it, decrement the reference count of 205 /// the specified Store object. If the reference count hits 0, the memory 206 /// associated with the object is recycled. 207 virtual void decrementReferenceCount(Store store) {} 208 209 using InvalidatedRegions = SmallVector<const MemRegion *, 8>; 210 211 /// invalidateRegions - Clears out the specified regions from the store, 212 /// marking their values as unknown. Depending on the store, this may also 213 /// invalidate additional regions that may have changed based on accessing 214 /// the given regions. Optionally, invalidates non-static globals as well. 215 /// \param[in] store The initial store 216 /// \param[in] Values The values to invalidate. 217 /// \param[in] E The current statement being evaluated. Used to conjure 218 /// symbols to mark the values of invalidated regions. 219 /// \param[in] Count The current block count. Used to conjure 220 /// symbols to mark the values of invalidated regions. 221 /// \param[in] Call The call expression which will be used to determine which 222 /// globals should get invalidated. 223 /// \param[in,out] IS A set to fill with any symbols that are no longer 224 /// accessible. Pass \c NULL if this information will not be used. 225 /// \param[in] ITraits Information about invalidation for a particular 226 /// region/symbol. 227 /// \param[in,out] InvalidatedTopLevel A vector to fill with regions 228 //// explicitly being invalidated. Pass \c NULL if this 229 /// information will not be used. 230 /// \param[in,out] Invalidated A vector to fill with any regions being 231 /// invalidated. This should include any regions explicitly invalidated 232 /// even if they do not currently have bindings. Pass \c NULL if this 233 /// information will not be used. 234 virtual StoreRef invalidateRegions(Store store, 235 ArrayRef<SVal> Values, 236 const Expr *E, unsigned Count, 237 const LocationContext *LCtx, 238 const CallEvent *Call, 239 InvalidatedSymbols &IS, 240 RegionAndSymbolInvalidationTraits &ITraits, 241 InvalidatedRegions *InvalidatedTopLevel, 242 InvalidatedRegions *Invalidated) = 0; 243 244 /// enterStackFrame - Let the StoreManager to do something when execution 245 /// engine is about to execute into a callee. 246 StoreRef enterStackFrame(Store store, 247 const CallEvent &Call, 248 const StackFrameContext *CalleeCtx); 249 250 /// Finds the transitive closure of symbols within the given region. 251 /// 252 /// Returns false if the visitor aborted the scan. 253 virtual bool scanReachableSymbols(Store S, const MemRegion *R, 254 ScanReachableSymbols &Visitor) = 0; 255 256 virtual void printJson(raw_ostream &Out, Store S, const char *NL, 257 unsigned int Space, bool IsDot) const = 0; 258 259 class BindingsHandler { 260 public: 261 virtual ~BindingsHandler(); 262 263 /// \return whether the iteration should continue. 264 virtual bool HandleBinding(StoreManager& SMgr, Store store, 265 const MemRegion *region, SVal val) = 0; 266 }; 267 268 class FindUniqueBinding : public BindingsHandler { 269 SymbolRef Sym; 270 const MemRegion* Binding = nullptr; 271 bool First = true; 272 273 public: 274 FindUniqueBinding(SymbolRef sym) : Sym(sym) {} 275 276 explicit operator bool() { return First && Binding; } 277 278 bool HandleBinding(StoreManager& SMgr, Store store, const MemRegion* R, 279 SVal val) override; 280 const MemRegion *getRegion() { return Binding; } 281 }; 282 283 /// iterBindings - Iterate over the bindings in the Store. 284 virtual void iterBindings(Store store, BindingsHandler& f) = 0; 285 286 protected: 287 const ElementRegion *MakeElementRegion(const SubRegion *baseRegion, 288 QualType pointeeTy, 289 uint64_t index = 0); 290 291 /// CastRetrievedVal - Used by subclasses of StoreManager to implement 292 /// implicit casts that arise from loads from regions that are reinterpreted 293 /// as another region. 294 SVal CastRetrievedVal(SVal val, const TypedValueRegion *region, 295 QualType castTy); 296 297 private: 298 SVal getLValueFieldOrIvar(const Decl *decl, SVal base); 299 }; 300 301 inline StoreRef::StoreRef(Store store, StoreManager & smgr) 302 : store(store), mgr(smgr) { 303 if (store) 304 mgr.incrementReferenceCount(store); 305 } 306 307 inline StoreRef::StoreRef(const StoreRef &sr) 308 : store(sr.store), mgr(sr.mgr) 309 { 310 if (store) 311 mgr.incrementReferenceCount(store); 312 } 313 314 inline StoreRef::~StoreRef() { 315 if (store) 316 mgr.decrementReferenceCount(store); 317 } 318 319 inline StoreRef &StoreRef::operator=(StoreRef const &newStore) { 320 assert(&newStore.mgr == &mgr); 321 if (store != newStore.store) { 322 mgr.incrementReferenceCount(newStore.store); 323 mgr.decrementReferenceCount(store); 324 store = newStore.getStore(); 325 } 326 return *this; 327 } 328 329 // FIXME: Do we need to pass ProgramStateManager anymore? 330 std::unique_ptr<StoreManager> 331 CreateRegionStoreManager(ProgramStateManager &StMgr); 332 std::unique_ptr<StoreManager> 333 CreateFieldsOnlyRegionStoreManager(ProgramStateManager &StMgr); 334 335 } // namespace ento 336 337 } // namespace clang 338 339 #endif // LLVM_CLANG_STATICANALYZER_CORE_PATHSENSITIVE_STORE_H 340