1 // SValBuilder.h - Construction of SVals from evaluating expressions -*- 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 defines SValBuilder, a class that defines the interface for 10 // "symbolical evaluators" which construct an SVal from an expression. 11 // 12 //===----------------------------------------------------------------------===// 13 14 #ifndef LLVM_CLANG_STATICANALYZER_CORE_PATHSENSITIVE_SVALBUILDER_H 15 #define LLVM_CLANG_STATICANALYZER_CORE_PATHSENSITIVE_SVALBUILDER_H 16 17 #include "clang/AST/ASTContext.h" 18 #include "clang/AST/DeclarationName.h" 19 #include "clang/AST/Expr.h" 20 #include "clang/AST/ExprObjC.h" 21 #include "clang/AST/Type.h" 22 #include "clang/Basic/LLVM.h" 23 #include "clang/Basic/LangOptions.h" 24 #include "clang/StaticAnalyzer/Core/PathSensitive/BasicValueFactory.h" 25 #include "clang/StaticAnalyzer/Core/PathSensitive/MemRegion.h" 26 #include "clang/StaticAnalyzer/Core/PathSensitive/ProgramState_Fwd.h" 27 #include "clang/StaticAnalyzer/Core/PathSensitive/SVals.h" 28 #include "clang/StaticAnalyzer/Core/PathSensitive/SymExpr.h" 29 #include "clang/StaticAnalyzer/Core/PathSensitive/SymbolManager.h" 30 #include "llvm/ADT/ImmutableList.h" 31 #include <cstdint> 32 #include <optional> 33 34 namespace clang { 35 36 class AnalyzerOptions; 37 class BlockDecl; 38 class CXXBoolLiteralExpr; 39 class CXXMethodDecl; 40 class CXXRecordDecl; 41 class DeclaratorDecl; 42 class FunctionDecl; 43 class LocationContext; 44 class StackFrameContext; 45 class Stmt; 46 47 namespace ento { 48 49 class ConditionTruthVal; 50 class ProgramStateManager; 51 class StoreRef; 52 53 class SValBuilder { 54 virtual void anchor(); 55 56 protected: 57 ASTContext &Context; 58 59 /// Manager of APSInt values. 60 BasicValueFactory BasicVals; 61 62 /// Manages the creation of symbols. 63 SymbolManager SymMgr; 64 65 /// Manages the creation of memory regions. 66 MemRegionManager MemMgr; 67 68 ProgramStateManager &StateMgr; 69 70 const AnalyzerOptions &AnOpts; 71 72 /// The scalar type to use for array indices. 73 const QualType ArrayIndexTy; 74 75 /// The width of the scalar type used for array indices. 76 const unsigned ArrayIndexWidth; 77 78 public: 79 SValBuilder(llvm::BumpPtrAllocator &alloc, ASTContext &context, 80 ProgramStateManager &stateMgr); 81 82 virtual ~SValBuilder() = default; 83 84 SVal evalCast(SVal V, QualType CastTy, QualType OriginalTy); 85 86 // Handles casts of type CK_IntegralCast. 87 SVal evalIntegralCast(ProgramStateRef state, SVal val, QualType castTy, 88 QualType originalType); 89 90 SVal evalMinus(NonLoc val); 91 SVal evalComplement(NonLoc val); 92 93 /// Create a new value which represents a binary expression with two non- 94 /// location operands. 95 virtual SVal evalBinOpNN(ProgramStateRef state, BinaryOperator::Opcode op, 96 NonLoc lhs, NonLoc rhs, QualType resultTy) = 0; 97 98 /// Create a new value which represents a binary expression with two memory 99 /// location operands. 100 virtual SVal evalBinOpLL(ProgramStateRef state, BinaryOperator::Opcode op, 101 Loc lhs, Loc rhs, QualType resultTy) = 0; 102 103 /// Create a new value which represents a binary expression with a memory 104 /// location and non-location operands. For example, this would be used to 105 /// evaluate a pointer arithmetic operation. 106 virtual SVal evalBinOpLN(ProgramStateRef state, BinaryOperator::Opcode op, 107 Loc lhs, NonLoc rhs, QualType resultTy) = 0; 108 109 /// Evaluates a given SVal. If the SVal has only one possible (integer) value, 110 /// that value is returned. Otherwise, returns NULL. 111 virtual const llvm::APSInt *getKnownValue(ProgramStateRef state, SVal val) = 0; 112 113 /// Simplify symbolic expressions within a given SVal. Return an SVal 114 /// that represents the same value, but is hopefully easier to work with 115 /// than the original SVal. 116 virtual SVal simplifySVal(ProgramStateRef State, SVal Val) = 0; 117 118 /// Constructs a symbolic expression for two non-location values. 119 SVal makeSymExprValNN(BinaryOperator::Opcode op, 120 NonLoc lhs, NonLoc rhs, QualType resultTy); 121 122 SVal evalUnaryOp(ProgramStateRef state, UnaryOperator::Opcode opc, 123 SVal operand, QualType type); 124 125 SVal evalBinOp(ProgramStateRef state, BinaryOperator::Opcode op, 126 SVal lhs, SVal rhs, QualType type); 127 128 /// \return Whether values in \p lhs and \p rhs are equal at \p state. 129 ConditionTruthVal areEqual(ProgramStateRef state, SVal lhs, SVal rhs); 130 131 SVal evalEQ(ProgramStateRef state, SVal lhs, SVal rhs); 132 133 DefinedOrUnknownSVal evalEQ(ProgramStateRef state, DefinedOrUnknownSVal lhs, 134 DefinedOrUnknownSVal rhs); 135 getContext()136 ASTContext &getContext() { return Context; } getContext()137 const ASTContext &getContext() const { return Context; } 138 getStateManager()139 ProgramStateManager &getStateManager() { return StateMgr; } 140 getConditionType()141 QualType getConditionType() const { 142 return Context.getLangOpts().CPlusPlus ? Context.BoolTy : Context.IntTy; 143 } 144 getArrayIndexType()145 QualType getArrayIndexType() const { 146 return ArrayIndexTy; 147 } 148 getBasicValueFactory()149 BasicValueFactory &getBasicValueFactory() { return BasicVals; } getBasicValueFactory()150 const BasicValueFactory &getBasicValueFactory() const { return BasicVals; } 151 getSymbolManager()152 SymbolManager &getSymbolManager() { return SymMgr; } getSymbolManager()153 const SymbolManager &getSymbolManager() const { return SymMgr; } 154 getRegionManager()155 MemRegionManager &getRegionManager() { return MemMgr; } getRegionManager()156 const MemRegionManager &getRegionManager() const { return MemMgr; } 157 getAnalyzerOptions()158 const AnalyzerOptions &getAnalyzerOptions() const { return AnOpts; } 159 160 // Forwarding methods to SymbolManager. 161 162 const SymbolConjured* conjureSymbol(const Stmt *stmt, 163 const LocationContext *LCtx, 164 QualType type, 165 unsigned visitCount, 166 const void *symbolTag = nullptr) { 167 return SymMgr.conjureSymbol(stmt, LCtx, type, visitCount, symbolTag); 168 } 169 170 const SymbolConjured* conjureSymbol(const Expr *expr, 171 const LocationContext *LCtx, 172 unsigned visitCount, 173 const void *symbolTag = nullptr) { 174 return SymMgr.conjureSymbol(expr, LCtx, visitCount, symbolTag); 175 } 176 177 /// Construct an SVal representing '0' for the specified type. 178 DefinedOrUnknownSVal makeZeroVal(QualType type); 179 180 /// Make a unique symbol for value of region. 181 DefinedOrUnknownSVal getRegionValueSymbolVal(const TypedValueRegion *region); 182 183 /// Create a new symbol with a unique 'name'. 184 /// 185 /// We resort to conjured symbols when we cannot construct a derived symbol. 186 /// The advantage of symbols derived/built from other symbols is that we 187 /// preserve the relation between related(or even equivalent) expressions, so 188 /// conjured symbols should be used sparingly. 189 DefinedOrUnknownSVal conjureSymbolVal(const void *symbolTag, 190 const Expr *expr, 191 const LocationContext *LCtx, 192 unsigned count); 193 DefinedOrUnknownSVal conjureSymbolVal(const void *symbolTag, 194 const Expr *expr, 195 const LocationContext *LCtx, 196 QualType type, 197 unsigned count); 198 DefinedOrUnknownSVal conjureSymbolVal(const Stmt *stmt, 199 const LocationContext *LCtx, 200 QualType type, 201 unsigned visitCount); 202 203 /// Conjure a symbol representing heap allocated memory region. 204 /// 205 /// Note, the expression should represent a location. 206 DefinedOrUnknownSVal getConjuredHeapSymbolVal(const Expr *E, 207 const LocationContext *LCtx, 208 unsigned Count); 209 210 /// Conjure a symbol representing heap allocated memory region. 211 /// 212 /// Note, now, the expression *doesn't* need to represent a location. 213 /// But the type need to! 214 DefinedOrUnknownSVal getConjuredHeapSymbolVal(const Expr *E, 215 const LocationContext *LCtx, 216 QualType type, unsigned Count); 217 218 DefinedOrUnknownSVal getDerivedRegionValueSymbolVal( 219 SymbolRef parentSymbol, const TypedValueRegion *region); 220 221 DefinedSVal getMetadataSymbolVal(const void *symbolTag, 222 const MemRegion *region, 223 const Expr *expr, QualType type, 224 const LocationContext *LCtx, 225 unsigned count); 226 227 DefinedSVal getMemberPointer(const NamedDecl *ND); 228 229 DefinedSVal getFunctionPointer(const FunctionDecl *func); 230 231 DefinedSVal getBlockPointer(const BlockDecl *block, CanQualType locTy, 232 const LocationContext *locContext, 233 unsigned blockCount); 234 235 /// Returns the value of \p E, if it can be determined in a non-path-sensitive 236 /// manner. 237 /// 238 /// If \p E is not a constant or cannot be modeled, returns \c std::nullopt. 239 std::optional<SVal> getConstantVal(const Expr *E); 240 makeCompoundVal(QualType type,llvm::ImmutableList<SVal> vals)241 NonLoc makeCompoundVal(QualType type, llvm::ImmutableList<SVal> vals) { 242 return nonloc::CompoundVal(BasicVals.getCompoundValData(type, vals)); 243 } 244 makeLazyCompoundVal(const StoreRef & store,const TypedValueRegion * region)245 NonLoc makeLazyCompoundVal(const StoreRef &store, 246 const TypedValueRegion *region) { 247 return nonloc::LazyCompoundVal( 248 BasicVals.getLazyCompoundValData(store, region)); 249 } 250 makePointerToMember(const DeclaratorDecl * DD)251 NonLoc makePointerToMember(const DeclaratorDecl *DD) { 252 return nonloc::PointerToMember(DD); 253 } 254 makePointerToMember(const PointerToMemberData * PTMD)255 NonLoc makePointerToMember(const PointerToMemberData *PTMD) { 256 return nonloc::PointerToMember(PTMD); 257 } 258 makeZeroArrayIndex()259 NonLoc makeZeroArrayIndex() { 260 return nonloc::ConcreteInt(BasicVals.getValue(0, ArrayIndexTy)); 261 } 262 makeArrayIndex(uint64_t idx)263 NonLoc makeArrayIndex(uint64_t idx) { 264 return nonloc::ConcreteInt(BasicVals.getValue(idx, ArrayIndexTy)); 265 } 266 267 SVal convertToArrayIndex(SVal val); 268 makeIntVal(const IntegerLiteral * integer)269 nonloc::ConcreteInt makeIntVal(const IntegerLiteral* integer) { 270 return nonloc::ConcreteInt( 271 BasicVals.getValue(integer->getValue(), 272 integer->getType()->isUnsignedIntegerOrEnumerationType())); 273 } 274 makeBoolVal(const ObjCBoolLiteralExpr * boolean)275 nonloc::ConcreteInt makeBoolVal(const ObjCBoolLiteralExpr *boolean) { 276 return makeTruthVal(boolean->getValue(), boolean->getType()); 277 } 278 279 nonloc::ConcreteInt makeBoolVal(const CXXBoolLiteralExpr *boolean); 280 makeIntVal(const llvm::APSInt & integer)281 nonloc::ConcreteInt makeIntVal(const llvm::APSInt& integer) { 282 return nonloc::ConcreteInt(BasicVals.getValue(integer)); 283 } 284 makeIntLocVal(const llvm::APSInt & integer)285 loc::ConcreteInt makeIntLocVal(const llvm::APSInt &integer) { 286 return loc::ConcreteInt(BasicVals.getValue(integer)); 287 } 288 makeIntVal(const llvm::APInt & integer,bool isUnsigned)289 NonLoc makeIntVal(const llvm::APInt& integer, bool isUnsigned) { 290 return nonloc::ConcreteInt(BasicVals.getValue(integer, isUnsigned)); 291 } 292 makeIntVal(uint64_t integer,QualType type)293 DefinedSVal makeIntVal(uint64_t integer, QualType type) { 294 if (Loc::isLocType(type)) 295 return loc::ConcreteInt(BasicVals.getValue(integer, type)); 296 297 return nonloc::ConcreteInt(BasicVals.getValue(integer, type)); 298 } 299 makeIntVal(uint64_t integer,bool isUnsigned)300 NonLoc makeIntVal(uint64_t integer, bool isUnsigned) { 301 return nonloc::ConcreteInt(BasicVals.getIntValue(integer, isUnsigned)); 302 } 303 makeIntValWithWidth(QualType ptrType,uint64_t integer)304 NonLoc makeIntValWithWidth(QualType ptrType, uint64_t integer) { 305 return nonloc::ConcreteInt(BasicVals.getValue(integer, ptrType)); 306 } 307 makeLocAsInteger(Loc loc,unsigned bits)308 NonLoc makeLocAsInteger(Loc loc, unsigned bits) { 309 return nonloc::LocAsInteger(BasicVals.getPersistentSValWithData(loc, bits)); 310 } 311 312 nonloc::SymbolVal makeNonLoc(const SymExpr *lhs, BinaryOperator::Opcode op, 313 const llvm::APSInt &rhs, QualType type); 314 315 nonloc::SymbolVal makeNonLoc(const llvm::APSInt &rhs, 316 BinaryOperator::Opcode op, const SymExpr *lhs, 317 QualType type); 318 319 nonloc::SymbolVal makeNonLoc(const SymExpr *lhs, BinaryOperator::Opcode op, 320 const SymExpr *rhs, QualType type); 321 322 NonLoc makeNonLoc(const SymExpr *operand, UnaryOperator::Opcode op, 323 QualType type); 324 325 /// Create a NonLoc value for cast. 326 nonloc::SymbolVal makeNonLoc(const SymExpr *operand, QualType fromTy, 327 QualType toTy); 328 makeTruthVal(bool b,QualType type)329 nonloc::ConcreteInt makeTruthVal(bool b, QualType type) { 330 return nonloc::ConcreteInt(BasicVals.getTruthValue(b, type)); 331 } 332 makeTruthVal(bool b)333 nonloc::ConcreteInt makeTruthVal(bool b) { 334 return nonloc::ConcreteInt(BasicVals.getTruthValue(b)); 335 } 336 337 /// Create NULL pointer, with proper pointer bit-width for given address 338 /// space. 339 /// \param type pointer type. makeNullWithType(QualType type)340 loc::ConcreteInt makeNullWithType(QualType type) { 341 // We cannot use the `isAnyPointerType()`. 342 assert((type->isPointerType() || type->isObjCObjectPointerType() || 343 type->isBlockPointerType() || type->isNullPtrType() || 344 type->isReferenceType()) && 345 "makeNullWithType must use pointer type"); 346 347 // The `sizeof(T&)` is `sizeof(T)`, thus we replace the reference with a 348 // pointer. Here we assume that references are actually implemented by 349 // pointers under-the-hood. 350 type = type->isReferenceType() 351 ? Context.getPointerType(type->getPointeeType()) 352 : type; 353 return loc::ConcreteInt(BasicVals.getZeroWithTypeSize(type)); 354 } 355 makeLoc(SymbolRef sym)356 loc::MemRegionVal makeLoc(SymbolRef sym) { 357 return loc::MemRegionVal(MemMgr.getSymbolicRegion(sym)); 358 } 359 makeLoc(const MemRegion * region)360 loc::MemRegionVal makeLoc(const MemRegion *region) { 361 return loc::MemRegionVal(region); 362 } 363 makeLoc(const AddrLabelExpr * expr)364 loc::GotoLabel makeLoc(const AddrLabelExpr *expr) { 365 return loc::GotoLabel(expr->getLabel()); 366 } 367 makeLoc(const llvm::APSInt & integer)368 loc::ConcreteInt makeLoc(const llvm::APSInt &integer) { 369 return loc::ConcreteInt(BasicVals.getValue(integer)); 370 } 371 372 /// Return MemRegionVal on success cast, otherwise return std::nullopt. 373 std::optional<loc::MemRegionVal> 374 getCastedMemRegionVal(const MemRegion *region, QualType type); 375 376 /// Make an SVal that represents the given symbol. This follows the convention 377 /// of representing Loc-type symbols (symbolic pointers and references) 378 /// as Loc values wrapping the symbol rather than as plain symbol values. makeSymbolVal(SymbolRef Sym)379 DefinedSVal makeSymbolVal(SymbolRef Sym) { 380 if (Loc::isLocType(Sym->getType())) 381 return makeLoc(Sym); 382 return nonloc::SymbolVal(Sym); 383 } 384 385 /// Return a memory region for the 'this' object reference. 386 loc::MemRegionVal getCXXThis(const CXXMethodDecl *D, 387 const StackFrameContext *SFC); 388 389 /// Return a memory region for the 'this' object reference. 390 loc::MemRegionVal getCXXThis(const CXXRecordDecl *D, 391 const StackFrameContext *SFC); 392 }; 393 394 SValBuilder* createSimpleSValBuilder(llvm::BumpPtrAllocator &alloc, 395 ASTContext &context, 396 ProgramStateManager &stateMgr); 397 398 } // namespace ento 399 400 } // namespace clang 401 402 #endif // LLVM_CLANG_STATICANALYZER_CORE_PATHSENSITIVE_SVALBUILDER_H 403