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