1 //== Store.cpp - Interface for maps from Locations to Values ----*- 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 defined the types Store and StoreManager. 11 // 12 //===----------------------------------------------------------------------===// 13 14 #include "clang/StaticAnalyzer/Core/PathSensitive/Store.h" 15 #include "clang/StaticAnalyzer/Core/PathSensitive/ProgramState.h" 16 #include "clang/AST/CharUnits.h" 17 #include "clang/AST/DeclObjC.h" 18 19 using namespace clang; 20 using namespace ento; 21 22 StoreManager::StoreManager(ProgramStateManager &stateMgr) 23 : svalBuilder(stateMgr.getSValBuilder()), StateMgr(stateMgr), 24 MRMgr(svalBuilder.getRegionManager()), Ctx(stateMgr.getContext()) {} 25 26 StoreRef StoreManager::enterStackFrame(ProgramStateRef state, 27 const LocationContext *callerCtx, 28 const StackFrameContext *calleeCtx) { 29 return StoreRef(state->getStore(), *this); 30 } 31 32 const MemRegion *StoreManager::MakeElementRegion(const MemRegion *Base, 33 QualType EleTy, uint64_t index) { 34 NonLoc idx = svalBuilder.makeArrayIndex(index); 35 return MRMgr.getElementRegion(EleTy, idx, Base, svalBuilder.getContext()); 36 } 37 38 // FIXME: Merge with the implementation of the same method in MemRegion.cpp 39 static bool IsCompleteType(ASTContext &Ctx, QualType Ty) { 40 if (const RecordType *RT = Ty->getAs<RecordType>()) { 41 const RecordDecl *D = RT->getDecl(); 42 if (!D->getDefinition()) 43 return false; 44 } 45 46 return true; 47 } 48 49 StoreRef StoreManager::BindDefault(Store store, const MemRegion *R, SVal V) { 50 return StoreRef(store, *this); 51 } 52 53 const ElementRegion *StoreManager::GetElementZeroRegion(const MemRegion *R, 54 QualType T) { 55 NonLoc idx = svalBuilder.makeZeroArrayIndex(); 56 assert(!T.isNull()); 57 return MRMgr.getElementRegion(T, idx, R, Ctx); 58 } 59 60 const MemRegion *StoreManager::castRegion(const MemRegion *R, QualType CastToTy) { 61 62 ASTContext &Ctx = StateMgr.getContext(); 63 64 // Handle casts to Objective-C objects. 65 if (CastToTy->isObjCObjectPointerType()) 66 return R->StripCasts(); 67 68 if (CastToTy->isBlockPointerType()) { 69 // FIXME: We may need different solutions, depending on the symbol 70 // involved. Blocks can be casted to/from 'id', as they can be treated 71 // as Objective-C objects. This could possibly be handled by enhancing 72 // our reasoning of downcasts of symbolic objects. 73 if (isa<CodeTextRegion>(R) || isa<SymbolicRegion>(R)) 74 return R; 75 76 // We don't know what to make of it. Return a NULL region, which 77 // will be interpretted as UnknownVal. 78 return NULL; 79 } 80 81 // Now assume we are casting from pointer to pointer. Other cases should 82 // already be handled. 83 QualType PointeeTy = CastToTy->getPointeeType(); 84 QualType CanonPointeeTy = Ctx.getCanonicalType(PointeeTy); 85 86 // Handle casts to void*. We just pass the region through. 87 if (CanonPointeeTy.getLocalUnqualifiedType() == Ctx.VoidTy) 88 return R; 89 90 // Handle casts from compatible types. 91 if (R->isBoundable()) 92 if (const TypedValueRegion *TR = dyn_cast<TypedValueRegion>(R)) { 93 QualType ObjTy = Ctx.getCanonicalType(TR->getValueType()); 94 if (CanonPointeeTy == ObjTy) 95 return R; 96 } 97 98 // Process region cast according to the kind of the region being cast. 99 switch (R->getKind()) { 100 case MemRegion::CXXThisRegionKind: 101 case MemRegion::GenericMemSpaceRegionKind: 102 case MemRegion::StackLocalsSpaceRegionKind: 103 case MemRegion::StackArgumentsSpaceRegionKind: 104 case MemRegion::HeapSpaceRegionKind: 105 case MemRegion::UnknownSpaceRegionKind: 106 case MemRegion::StaticGlobalSpaceRegionKind: 107 case MemRegion::GlobalInternalSpaceRegionKind: 108 case MemRegion::GlobalSystemSpaceRegionKind: 109 case MemRegion::GlobalImmutableSpaceRegionKind: { 110 llvm_unreachable("Invalid region cast"); 111 } 112 113 case MemRegion::FunctionTextRegionKind: 114 case MemRegion::BlockTextRegionKind: 115 case MemRegion::BlockDataRegionKind: 116 case MemRegion::StringRegionKind: 117 // FIXME: Need to handle arbitrary downcasts. 118 case MemRegion::SymbolicRegionKind: 119 case MemRegion::AllocaRegionKind: 120 case MemRegion::CompoundLiteralRegionKind: 121 case MemRegion::FieldRegionKind: 122 case MemRegion::ObjCIvarRegionKind: 123 case MemRegion::ObjCStringRegionKind: 124 case MemRegion::VarRegionKind: 125 case MemRegion::CXXTempObjectRegionKind: 126 case MemRegion::CXXBaseObjectRegionKind: 127 return MakeElementRegion(R, PointeeTy); 128 129 case MemRegion::ElementRegionKind: { 130 // If we are casting from an ElementRegion to another type, the 131 // algorithm is as follows: 132 // 133 // (1) Compute the "raw offset" of the ElementRegion from the 134 // base region. This is done by calling 'getAsRawOffset()'. 135 // 136 // (2a) If we get a 'RegionRawOffset' after calling 137 // 'getAsRawOffset()', determine if the absolute offset 138 // can be exactly divided into chunks of the size of the 139 // casted-pointee type. If so, create a new ElementRegion with 140 // the pointee-cast type as the new ElementType and the index 141 // being the offset divded by the chunk size. If not, create 142 // a new ElementRegion at offset 0 off the raw offset region. 143 // 144 // (2b) If we don't a get a 'RegionRawOffset' after calling 145 // 'getAsRawOffset()', it means that we are at offset 0. 146 // 147 // FIXME: Handle symbolic raw offsets. 148 149 const ElementRegion *elementR = cast<ElementRegion>(R); 150 const RegionRawOffset &rawOff = elementR->getAsArrayOffset(); 151 const MemRegion *baseR = rawOff.getRegion(); 152 153 // If we cannot compute a raw offset, throw up our hands and return 154 // a NULL MemRegion*. 155 if (!baseR) 156 return NULL; 157 158 CharUnits off = rawOff.getOffset(); 159 160 if (off.isZero()) { 161 // Edge case: we are at 0 bytes off the beginning of baseR. We 162 // check to see if type we are casting to is the same as the base 163 // region. If so, just return the base region. 164 if (const TypedValueRegion *TR = dyn_cast<TypedValueRegion>(baseR)) { 165 QualType ObjTy = Ctx.getCanonicalType(TR->getValueType()); 166 QualType CanonPointeeTy = Ctx.getCanonicalType(PointeeTy); 167 if (CanonPointeeTy == ObjTy) 168 return baseR; 169 } 170 171 // Otherwise, create a new ElementRegion at offset 0. 172 return MakeElementRegion(baseR, PointeeTy); 173 } 174 175 // We have a non-zero offset from the base region. We want to determine 176 // if the offset can be evenly divided by sizeof(PointeeTy). If so, 177 // we create an ElementRegion whose index is that value. Otherwise, we 178 // create two ElementRegions, one that reflects a raw offset and the other 179 // that reflects the cast. 180 181 // Compute the index for the new ElementRegion. 182 int64_t newIndex = 0; 183 const MemRegion *newSuperR = 0; 184 185 // We can only compute sizeof(PointeeTy) if it is a complete type. 186 if (IsCompleteType(Ctx, PointeeTy)) { 187 // Compute the size in **bytes**. 188 CharUnits pointeeTySize = Ctx.getTypeSizeInChars(PointeeTy); 189 if (!pointeeTySize.isZero()) { 190 // Is the offset a multiple of the size? If so, we can layer the 191 // ElementRegion (with elementType == PointeeTy) directly on top of 192 // the base region. 193 if (off % pointeeTySize == 0) { 194 newIndex = off / pointeeTySize; 195 newSuperR = baseR; 196 } 197 } 198 } 199 200 if (!newSuperR) { 201 // Create an intermediate ElementRegion to represent the raw byte. 202 // This will be the super region of the final ElementRegion. 203 newSuperR = MakeElementRegion(baseR, Ctx.CharTy, off.getQuantity()); 204 } 205 206 return MakeElementRegion(newSuperR, PointeeTy, newIndex); 207 } 208 } 209 210 llvm_unreachable("unreachable"); 211 } 212 213 214 /// CastRetrievedVal - Used by subclasses of StoreManager to implement 215 /// implicit casts that arise from loads from regions that are reinterpreted 216 /// as another region. 217 SVal StoreManager::CastRetrievedVal(SVal V, const TypedValueRegion *R, 218 QualType castTy, bool performTestOnly) { 219 220 if (castTy.isNull() || V.isUnknownOrUndef()) 221 return V; 222 223 ASTContext &Ctx = svalBuilder.getContext(); 224 225 if (performTestOnly) { 226 // Automatically translate references to pointers. 227 QualType T = R->getValueType(); 228 if (const ReferenceType *RT = T->getAs<ReferenceType>()) 229 T = Ctx.getPointerType(RT->getPointeeType()); 230 231 assert(svalBuilder.getContext().hasSameUnqualifiedType(castTy, T)); 232 return V; 233 } 234 235 return svalBuilder.dispatchCast(V, castTy); 236 } 237 238 SVal StoreManager::getLValueFieldOrIvar(const Decl *D, SVal Base) { 239 if (Base.isUnknownOrUndef()) 240 return Base; 241 242 Loc BaseL = cast<Loc>(Base); 243 const MemRegion* BaseR = 0; 244 245 switch (BaseL.getSubKind()) { 246 case loc::MemRegionKind: 247 BaseR = cast<loc::MemRegionVal>(BaseL).getRegion(); 248 break; 249 250 case loc::GotoLabelKind: 251 // These are anormal cases. Flag an undefined value. 252 return UndefinedVal(); 253 254 case loc::ConcreteIntKind: 255 // While these seem funny, this can happen through casts. 256 // FIXME: What we should return is the field offset. For example, 257 // add the field offset to the integer value. That way funny things 258 // like this work properly: &(((struct foo *) 0xa)->f) 259 return Base; 260 261 default: 262 llvm_unreachable("Unhandled Base."); 263 } 264 265 // NOTE: We must have this check first because ObjCIvarDecl is a subclass 266 // of FieldDecl. 267 if (const ObjCIvarDecl *ID = dyn_cast<ObjCIvarDecl>(D)) 268 return loc::MemRegionVal(MRMgr.getObjCIvarRegion(ID, BaseR)); 269 270 return loc::MemRegionVal(MRMgr.getFieldRegion(cast<FieldDecl>(D), BaseR)); 271 } 272 273 SVal StoreManager::getLValueIvar(const ObjCIvarDecl *decl, SVal base) { 274 return getLValueFieldOrIvar(decl, base); 275 } 276 277 SVal StoreManager::getLValueElement(QualType elementType, NonLoc Offset, 278 SVal Base) { 279 280 // If the base is an unknown or undefined value, just return it back. 281 // FIXME: For absolute pointer addresses, we just return that value back as 282 // well, although in reality we should return the offset added to that 283 // value. 284 if (Base.isUnknownOrUndef() || isa<loc::ConcreteInt>(Base)) 285 return Base; 286 287 const MemRegion* BaseRegion = cast<loc::MemRegionVal>(Base).getRegion(); 288 289 // Pointer of any type can be cast and used as array base. 290 const ElementRegion *ElemR = dyn_cast<ElementRegion>(BaseRegion); 291 292 // Convert the offset to the appropriate size and signedness. 293 Offset = cast<NonLoc>(svalBuilder.convertToArrayIndex(Offset)); 294 295 if (!ElemR) { 296 // 297 // If the base region is not an ElementRegion, create one. 298 // This can happen in the following example: 299 // 300 // char *p = __builtin_alloc(10); 301 // p[1] = 8; 302 // 303 // Observe that 'p' binds to an AllocaRegion. 304 // 305 return loc::MemRegionVal(MRMgr.getElementRegion(elementType, Offset, 306 BaseRegion, Ctx)); 307 } 308 309 SVal BaseIdx = ElemR->getIndex(); 310 311 if (!isa<nonloc::ConcreteInt>(BaseIdx)) 312 return UnknownVal(); 313 314 const llvm::APSInt& BaseIdxI = cast<nonloc::ConcreteInt>(BaseIdx).getValue(); 315 316 // Only allow non-integer offsets if the base region has no offset itself. 317 // FIXME: This is a somewhat arbitrary restriction. We should be using 318 // SValBuilder here to add the two offsets without checking their types. 319 if (!isa<nonloc::ConcreteInt>(Offset)) { 320 if (isa<ElementRegion>(BaseRegion->StripCasts())) 321 return UnknownVal(); 322 323 return loc::MemRegionVal(MRMgr.getElementRegion(elementType, Offset, 324 ElemR->getSuperRegion(), 325 Ctx)); 326 } 327 328 const llvm::APSInt& OffI = cast<nonloc::ConcreteInt>(Offset).getValue(); 329 assert(BaseIdxI.isSigned()); 330 331 // Compute the new index. 332 nonloc::ConcreteInt NewIdx(svalBuilder.getBasicValueFactory().getValue(BaseIdxI + 333 OffI)); 334 335 // Construct the new ElementRegion. 336 const MemRegion *ArrayR = ElemR->getSuperRegion(); 337 return loc::MemRegionVal(MRMgr.getElementRegion(elementType, NewIdx, ArrayR, 338 Ctx)); 339 } 340 341 StoreManager::BindingsHandler::~BindingsHandler() {} 342 343 bool StoreManager::FindUniqueBinding::HandleBinding(StoreManager& SMgr, 344 Store store, 345 const MemRegion* R, 346 SVal val) { 347 SymbolRef SymV = val.getAsLocSymbol(); 348 if (!SymV || SymV != Sym) 349 return true; 350 351 if (Binding) { 352 First = false; 353 return false; 354 } 355 else 356 Binding = R; 357 358 return true; 359 } 360 361 void SubRegionMap::anchor() { } 362 void SubRegionMap::Visitor::anchor() { } 363