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/SmallVector.h" 27 #include <cassert> 28 #include <cstdint> 29 #include <memory> 30 #include <optional> 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 std::optional<SVal> getDefaultBinding(Store store, 87 const MemRegion *R) = 0; 88 89 /// Return the default value bound to a LazyCompoundVal. The default binding 90 /// is used to represent the value of any fields or elements within the 91 /// structure represented by the LazyCompoundVal which were not initialized 92 /// explicitly separately from the whole structure. Default binding may be an 93 /// unknown, undefined, concrete, or symbolic value. 94 /// \param[in] lcv The lazy compound value. 95 /// \return The default value bound to the LazyCompoundVal \c lcv, if a 96 /// default binding exists. 97 std::optional<SVal> getDefaultBinding(nonloc::LazyCompoundVal lcv) { 98 return getDefaultBinding(lcv.getStore(), lcv.getRegion()); 99 } 100 101 /// Return a store with the specified value bound to the given location. 102 /// \param[in] store The store in which to make the binding. 103 /// \param[in] loc The symbolic memory location. 104 /// \param[in] val The value to bind to location \c loc. 105 /// \return A StoreRef object that contains the same 106 /// bindings as \c store with the addition of having the value specified 107 /// by \c val bound to the location given for \c loc. 108 virtual StoreRef Bind(Store store, Loc loc, SVal val) = 0; 109 110 /// Return a store with the specified value bound to all sub-regions of the 111 /// region. The region must not have previous bindings. If you need to 112 /// invalidate existing bindings, consider invalidateRegions(). 113 virtual StoreRef BindDefaultInitial(Store store, const MemRegion *R, 114 SVal V) = 0; 115 116 /// Return a store with in which all values within the given region are 117 /// reset to zero. This method is allowed to overwrite previous bindings. 118 virtual StoreRef BindDefaultZero(Store store, const MemRegion *R) = 0; 119 120 /// Create a new store with the specified binding removed. 121 /// \param ST the original store, that is the basis for the new store. 122 /// \param L the location whose binding should be removed. 123 virtual StoreRef killBinding(Store ST, Loc L) = 0; 124 125 /// getInitialStore - Returns the initial "empty" store representing the 126 /// value bindings upon entry to an analyzed function. 127 virtual StoreRef getInitialStore(const LocationContext *InitLoc) = 0; 128 129 /// getRegionManager - Returns the internal RegionManager object that is 130 /// used to query and manipulate MemRegion objects. 131 MemRegionManager& getRegionManager() { return MRMgr; } 132 133 SValBuilder& getSValBuilder() { return svalBuilder; } 134 135 virtual Loc getLValueVar(const VarDecl *VD, const LocationContext *LC) { 136 return svalBuilder.makeLoc(MRMgr.getVarRegion(VD, LC)); 137 } 138 139 Loc getLValueCompoundLiteral(const CompoundLiteralExpr *CL, 140 const LocationContext *LC) { 141 return loc::MemRegionVal(MRMgr.getCompoundLiteralRegion(CL, LC)); 142 } 143 144 virtual SVal getLValueIvar(const ObjCIvarDecl *decl, SVal base); 145 146 virtual SVal getLValueField(const FieldDecl *D, SVal Base) { 147 return getLValueFieldOrIvar(D, Base); 148 } 149 150 virtual SVal getLValueElement(QualType elementType, NonLoc offset, SVal Base); 151 152 /// ArrayToPointer - Used by ExprEngine::VistCast to handle implicit 153 /// conversions between arrays and pointers. 154 virtual SVal ArrayToPointer(Loc Array, QualType ElementTy) = 0; 155 156 /// Evaluates a chain of derived-to-base casts through the path specified in 157 /// \p Cast. 158 SVal evalDerivedToBase(SVal Derived, const CastExpr *Cast); 159 160 /// Evaluates a chain of derived-to-base casts through the specified path. 161 SVal evalDerivedToBase(SVal Derived, const CXXBasePath &CastPath); 162 163 /// Evaluates a derived-to-base cast through a single level of derivation. 164 SVal evalDerivedToBase(SVal Derived, QualType DerivedPtrType, 165 bool IsVirtual); 166 167 /// Attempts to do a down cast. Used to model BaseToDerived and C++ 168 /// dynamic_cast. 169 /// The callback may result in the following 3 scenarios: 170 /// - Successful cast (ex: derived is subclass of base). 171 /// - Failed cast (ex: derived is definitely not a subclass of base). 172 /// The distinction of this case from the next one is necessary to model 173 /// dynamic_cast. 174 /// - We don't know (base is a symbolic region and we don't have 175 /// enough info to determine if the cast will succeed at run time). 176 /// The function returns an optional with SVal representing the derived class 177 /// in case of a successful cast and `std::nullopt` otherwise. 178 std::optional<SVal> evalBaseToDerived(SVal Base, QualType DerivedPtrType); 179 180 const ElementRegion *GetElementZeroRegion(const SubRegion *R, QualType T); 181 182 /// castRegion - Used by ExprEngine::VisitCast to handle casts from 183 /// a MemRegion* to a specific location type. 'R' is the region being 184 /// casted and 'CastToTy' the result type of the cast. 185 std::optional<const MemRegion *> castRegion(const MemRegion *region, 186 QualType CastToTy); 187 188 virtual StoreRef removeDeadBindings(Store store, const StackFrameContext *LCtx, 189 SymbolReaper &SymReaper) = 0; 190 191 virtual bool includedInBindings(Store store, 192 const MemRegion *region) const = 0; 193 194 /// If the StoreManager supports it, increment the reference count of 195 /// the specified Store object. 196 virtual void incrementReferenceCount(Store store) {} 197 198 /// If the StoreManager supports it, decrement the reference count of 199 /// the specified Store object. If the reference count hits 0, the memory 200 /// associated with the object is recycled. 201 virtual void decrementReferenceCount(Store store) {} 202 203 using InvalidatedRegions = SmallVector<const MemRegion *, 8>; 204 205 /// invalidateRegions - Clears out the specified regions from the store, 206 /// marking their values as unknown. Depending on the store, this may also 207 /// invalidate additional regions that may have changed based on accessing 208 /// the given regions. If \p Call is non-null, then this also invalidates 209 /// non-static globals (but if \p Call is from a system header, then this is 210 /// limited to globals declared in system headers). 211 /// 212 /// Instead of calling this method directly, you should probably use 213 /// \c ProgramState::invalidateRegions, which calls this and then ensures that 214 /// the relevant checker callbacks are triggered. 215 /// 216 /// \param[in] store The initial store. 217 /// \param[in] Values The values to invalidate. 218 /// \param[in] S The current statement being evaluated. Used to conjure 219 /// symbols to mark the values of invalidated regions. 220 /// \param[in] Count The current block count. Used to conjure 221 /// symbols to mark the values of invalidated regions. 222 /// \param[in] Call The call expression which will be used to determine which 223 /// globals should get invalidated. 224 /// \param[in,out] IS A set to fill with any symbols that are no longer 225 /// accessible. Pass \c NULL if this information will not be used. 226 /// \param[in] ITraits Information about invalidation for a particular 227 /// region/symbol. 228 /// \param[in,out] InvalidatedTopLevel A vector to fill with regions 229 //// explicitly being invalidated. Pass \c NULL if this 230 /// information will not be used. 231 /// \param[in,out] Invalidated A vector to fill with any regions being 232 /// invalidated. This should include any regions explicitly invalidated 233 /// even if they do not currently have bindings. Pass \c NULL if this 234 /// information will not be used. 235 virtual StoreRef invalidateRegions( 236 Store store, ArrayRef<SVal> Values, const Stmt *S, unsigned Count, 237 const LocationContext *LCtx, const CallEvent *Call, 238 InvalidatedSymbols &IS, RegionAndSymbolInvalidationTraits &ITraits, 239 InvalidatedRegions *TopLevelRegions, InvalidatedRegions *Invalidated) = 0; 240 241 /// enterStackFrame - Let the StoreManager to do something when execution 242 /// engine is about to execute into a callee. 243 StoreRef enterStackFrame(Store store, 244 const CallEvent &Call, 245 const StackFrameContext *CalleeCtx); 246 247 /// Finds the transitive closure of symbols within the given region. 248 /// 249 /// Returns false if the visitor aborted the scan. 250 virtual bool scanReachableSymbols(Store S, const MemRegion *R, 251 ScanReachableSymbols &Visitor) = 0; 252 253 virtual void printJson(raw_ostream &Out, Store S, const char *NL, 254 unsigned int Space, bool IsDot) const = 0; 255 256 class BindingsHandler { 257 public: 258 virtual ~BindingsHandler(); 259 260 /// \return whether the iteration should continue. 261 virtual bool HandleBinding(StoreManager& SMgr, Store store, 262 const MemRegion *region, SVal val) = 0; 263 }; 264 265 class FindUniqueBinding : public BindingsHandler { 266 SymbolRef Sym; 267 const MemRegion* Binding = nullptr; 268 bool First = true; 269 270 public: 271 FindUniqueBinding(SymbolRef sym) : Sym(sym) {} 272 273 explicit operator bool() { return First && Binding; } 274 275 bool HandleBinding(StoreManager& SMgr, Store store, const MemRegion* R, 276 SVal val) override; 277 const MemRegion *getRegion() { return Binding; } 278 }; 279 280 /// iterBindings - Iterate over the bindings in the Store. 281 virtual void iterBindings(Store store, BindingsHandler& f) = 0; 282 283 protected: 284 const ElementRegion *MakeElementRegion(const SubRegion *baseRegion, 285 QualType pointeeTy, 286 uint64_t index = 0); 287 288 private: 289 SVal getLValueFieldOrIvar(const Decl *decl, SVal base); 290 }; 291 292 inline StoreRef::StoreRef(Store store, StoreManager & smgr) 293 : store(store), mgr(smgr) { 294 if (store) 295 mgr.incrementReferenceCount(store); 296 } 297 298 inline StoreRef::StoreRef(const StoreRef &sr) 299 : store(sr.store), mgr(sr.mgr) 300 { 301 if (store) 302 mgr.incrementReferenceCount(store); 303 } 304 305 inline StoreRef::~StoreRef() { 306 if (store) 307 mgr.decrementReferenceCount(store); 308 } 309 310 inline StoreRef &StoreRef::operator=(StoreRef const &newStore) { 311 assert(&newStore.mgr == &mgr); 312 if (store != newStore.store) { 313 mgr.incrementReferenceCount(newStore.store); 314 mgr.decrementReferenceCount(store); 315 store = newStore.getStore(); 316 } 317 return *this; 318 } 319 320 // FIXME: Do we need to pass ProgramStateManager anymore? 321 std::unique_ptr<StoreManager> 322 CreateRegionStoreManager(ProgramStateManager &StMgr); 323 324 } // namespace ento 325 326 } // namespace clang 327 328 #endif // LLVM_CLANG_STATICANALYZER_CORE_PATHSENSITIVE_STORE_H 329