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 /// Tries to get the minimal possible (integer) value of a given SVal. This 114 /// always returns the value of a ConcreteInt, but may return NULL if the 115 /// value is symbolic and the constraint manager cannot provide a useful 116 /// answer. 117 virtual const llvm::APSInt *getMinValue(ProgramStateRef state, SVal val) = 0; 118 119 /// Tries to get the maximal possible (integer) value of a given SVal. This 120 /// always returns the value of a ConcreteInt, but may return NULL if the 121 /// value is symbolic and the constraint manager cannot provide a useful 122 /// answer. 123 virtual const llvm::APSInt *getMaxValue(ProgramStateRef state, SVal val) = 0; 124 125 /// Simplify symbolic expressions within a given SVal. Return an SVal 126 /// that represents the same value, but is hopefully easier to work with 127 /// than the original SVal. 128 virtual SVal simplifySVal(ProgramStateRef State, SVal Val) = 0; 129 130 /// Constructs a symbolic expression for two non-location values. 131 SVal makeSymExprValNN(BinaryOperator::Opcode op, 132 NonLoc lhs, NonLoc rhs, QualType resultTy); 133 134 SVal evalUnaryOp(ProgramStateRef state, UnaryOperator::Opcode opc, 135 SVal operand, QualType type); 136 137 SVal evalBinOp(ProgramStateRef state, BinaryOperator::Opcode op, 138 SVal lhs, SVal rhs, QualType type); 139 140 /// \return Whether values in \p lhs and \p rhs are equal at \p state. 141 ConditionTruthVal areEqual(ProgramStateRef state, SVal lhs, SVal rhs); 142 143 SVal evalEQ(ProgramStateRef state, SVal lhs, SVal rhs); 144 145 DefinedOrUnknownSVal evalEQ(ProgramStateRef state, DefinedOrUnknownSVal lhs, 146 DefinedOrUnknownSVal rhs); 147 148 ASTContext &getContext() { return Context; } 149 const ASTContext &getContext() const { return Context; } 150 151 ProgramStateManager &getStateManager() { return StateMgr; } 152 153 QualType getConditionType() const { 154 return Context.getLangOpts().CPlusPlus ? Context.BoolTy : Context.IntTy; 155 } 156 157 QualType getArrayIndexType() const { 158 return ArrayIndexTy; 159 } 160 161 BasicValueFactory &getBasicValueFactory() { return BasicVals; } 162 const BasicValueFactory &getBasicValueFactory() const { return BasicVals; } 163 164 SymbolManager &getSymbolManager() { return SymMgr; } 165 const SymbolManager &getSymbolManager() const { return SymMgr; } 166 167 MemRegionManager &getRegionManager() { return MemMgr; } 168 const MemRegionManager &getRegionManager() const { return MemMgr; } 169 170 const AnalyzerOptions &getAnalyzerOptions() const { return AnOpts; } 171 172 // Forwarding methods to SymbolManager. 173 174 const SymbolConjured* conjureSymbol(const Stmt *stmt, 175 const LocationContext *LCtx, 176 QualType type, 177 unsigned visitCount, 178 const void *symbolTag = nullptr) { 179 return SymMgr.conjureSymbol(stmt, LCtx, type, visitCount, symbolTag); 180 } 181 182 const SymbolConjured* conjureSymbol(const Expr *expr, 183 const LocationContext *LCtx, 184 unsigned visitCount, 185 const void *symbolTag = nullptr) { 186 return SymMgr.conjureSymbol(expr, LCtx, visitCount, symbolTag); 187 } 188 189 /// Construct an SVal representing '0' for the specified type. 190 DefinedOrUnknownSVal makeZeroVal(QualType type); 191 192 /// Make a unique symbol for value of region. 193 DefinedOrUnknownSVal getRegionValueSymbolVal(const TypedValueRegion *region); 194 195 /// Create a new symbol with a unique 'name'. 196 /// 197 /// We resort to conjured symbols when we cannot construct a derived symbol. 198 /// The advantage of symbols derived/built from other symbols is that we 199 /// preserve the relation between related(or even equivalent) expressions, so 200 /// conjured symbols should be used sparingly. 201 DefinedOrUnknownSVal conjureSymbolVal(const void *symbolTag, 202 const Expr *expr, 203 const LocationContext *LCtx, 204 unsigned count); 205 DefinedOrUnknownSVal conjureSymbolVal(const void *symbolTag, const Stmt *S, 206 const LocationContext *LCtx, 207 QualType type, unsigned count); 208 DefinedOrUnknownSVal conjureSymbolVal(const Stmt *stmt, 209 const LocationContext *LCtx, 210 QualType type, 211 unsigned visitCount); 212 213 /// Conjure a symbol representing heap allocated memory region. 214 /// 215 /// Note, the expression should represent a location. 216 DefinedSVal getConjuredHeapSymbolVal(const Expr *E, 217 const LocationContext *LCtx, 218 unsigned Count); 219 220 /// Conjure a symbol representing heap allocated memory region. 221 /// 222 /// Note, now, the expression *doesn't* need to represent a location. 223 /// But the type need to! 224 DefinedSVal getConjuredHeapSymbolVal(const Expr *E, 225 const LocationContext *LCtx, 226 QualType type, unsigned Count); 227 228 /// Create an SVal representing the result of an alloca()-like call, that is, 229 /// an AllocaRegion on the stack. 230 /// 231 /// After calling this function, it's a good idea to set the extent of the 232 /// returned AllocaRegion. 233 loc::MemRegionVal getAllocaRegionVal(const Expr *E, 234 const LocationContext *LCtx, 235 unsigned Count); 236 237 DefinedOrUnknownSVal getDerivedRegionValueSymbolVal( 238 SymbolRef parentSymbol, const TypedValueRegion *region); 239 240 DefinedSVal getMetadataSymbolVal(const void *symbolTag, 241 const MemRegion *region, 242 const Expr *expr, QualType type, 243 const LocationContext *LCtx, 244 unsigned count); 245 246 DefinedSVal getMemberPointer(const NamedDecl *ND); 247 248 DefinedSVal getFunctionPointer(const FunctionDecl *func); 249 250 DefinedSVal getBlockPointer(const BlockDecl *block, CanQualType locTy, 251 const LocationContext *locContext, 252 unsigned blockCount); 253 254 /// Returns the value of \p E, if it can be determined in a non-path-sensitive 255 /// manner. 256 /// 257 /// If \p E is not a constant or cannot be modeled, returns \c std::nullopt. 258 std::optional<SVal> getConstantVal(const Expr *E); 259 260 NonLoc makeCompoundVal(QualType type, llvm::ImmutableList<SVal> vals) { 261 return nonloc::CompoundVal(BasicVals.getCompoundValData(type, vals)); 262 } 263 264 NonLoc makeLazyCompoundVal(const StoreRef &store, 265 const TypedValueRegion *region) { 266 return nonloc::LazyCompoundVal( 267 BasicVals.getLazyCompoundValData(store, region)); 268 } 269 270 NonLoc makePointerToMember(const DeclaratorDecl *DD) { 271 return nonloc::PointerToMember(DD); 272 } 273 274 NonLoc makePointerToMember(const PointerToMemberData *PTMD) { 275 return nonloc::PointerToMember(PTMD); 276 } 277 278 NonLoc makeZeroArrayIndex() { 279 return nonloc::ConcreteInt(BasicVals.getValue(0, ArrayIndexTy)); 280 } 281 282 NonLoc makeArrayIndex(uint64_t idx) { 283 return nonloc::ConcreteInt(BasicVals.getValue(idx, ArrayIndexTy)); 284 } 285 286 SVal convertToArrayIndex(SVal val); 287 288 nonloc::ConcreteInt makeIntVal(const IntegerLiteral* integer) { 289 return nonloc::ConcreteInt( 290 BasicVals.getValue(integer->getValue(), 291 integer->getType()->isUnsignedIntegerOrEnumerationType())); 292 } 293 294 nonloc::ConcreteInt makeBoolVal(const ObjCBoolLiteralExpr *boolean) { 295 return makeTruthVal(boolean->getValue(), boolean->getType()); 296 } 297 298 nonloc::ConcreteInt makeBoolVal(const CXXBoolLiteralExpr *boolean); 299 300 nonloc::ConcreteInt makeIntVal(const llvm::APSInt& integer) { 301 return nonloc::ConcreteInt(BasicVals.getValue(integer)); 302 } 303 304 loc::ConcreteInt makeIntLocVal(const llvm::APSInt &integer) { 305 return loc::ConcreteInt(BasicVals.getValue(integer)); 306 } 307 308 NonLoc makeIntVal(const llvm::APInt& integer, bool isUnsigned) { 309 return nonloc::ConcreteInt(BasicVals.getValue(integer, isUnsigned)); 310 } 311 312 DefinedSVal makeIntVal(uint64_t integer, QualType type) { 313 if (Loc::isLocType(type)) 314 return loc::ConcreteInt(BasicVals.getValue(integer, type)); 315 316 return nonloc::ConcreteInt(BasicVals.getValue(integer, type)); 317 } 318 319 NonLoc makeIntVal(uint64_t integer, bool isUnsigned) { 320 return nonloc::ConcreteInt(BasicVals.getIntValue(integer, isUnsigned)); 321 } 322 323 NonLoc makeIntValWithWidth(QualType ptrType, uint64_t integer) { 324 return nonloc::ConcreteInt(BasicVals.getValue(integer, ptrType)); 325 } 326 327 NonLoc makeLocAsInteger(Loc loc, unsigned bits) { 328 return nonloc::LocAsInteger(BasicVals.getPersistentSValWithData(loc, bits)); 329 } 330 331 nonloc::SymbolVal makeNonLoc(const SymExpr *lhs, BinaryOperator::Opcode op, 332 APSIntPtr rhs, QualType type); 333 334 nonloc::SymbolVal makeNonLoc(APSIntPtr rhs, BinaryOperator::Opcode op, 335 const SymExpr *lhs, QualType type); 336 337 nonloc::SymbolVal makeNonLoc(const SymExpr *lhs, BinaryOperator::Opcode op, 338 const SymExpr *rhs, QualType type); 339 340 NonLoc makeNonLoc(const SymExpr *operand, UnaryOperator::Opcode op, 341 QualType type); 342 343 /// Create a NonLoc value for cast. 344 nonloc::SymbolVal makeNonLoc(const SymExpr *operand, QualType fromTy, 345 QualType toTy); 346 347 nonloc::ConcreteInt makeTruthVal(bool b, QualType type) { 348 return nonloc::ConcreteInt(BasicVals.getTruthValue(b, type)); 349 } 350 351 nonloc::ConcreteInt makeTruthVal(bool b) { 352 return nonloc::ConcreteInt(BasicVals.getTruthValue(b)); 353 } 354 355 /// Create NULL pointer, with proper pointer bit-width for given address 356 /// space. 357 /// \param type pointer type. 358 loc::ConcreteInt makeNullWithType(QualType type) { 359 // We cannot use the `isAnyPointerType()`. 360 assert((type->isPointerType() || type->isObjCObjectPointerType() || 361 type->isBlockPointerType() || type->isNullPtrType() || 362 type->isReferenceType()) && 363 "makeNullWithType must use pointer type"); 364 365 // The `sizeof(T&)` is `sizeof(T)`, thus we replace the reference with a 366 // pointer. Here we assume that references are actually implemented by 367 // pointers under-the-hood. 368 type = type->isReferenceType() 369 ? Context.getPointerType(type->getPointeeType()) 370 : type; 371 return loc::ConcreteInt(BasicVals.getZeroWithTypeSize(type)); 372 } 373 374 loc::MemRegionVal makeLoc(SymbolRef sym) { 375 return loc::MemRegionVal(MemMgr.getSymbolicRegion(sym)); 376 } 377 378 loc::MemRegionVal makeLoc(const MemRegion *region) { 379 return loc::MemRegionVal(region); 380 } 381 382 loc::GotoLabel makeLoc(const AddrLabelExpr *expr) { 383 return loc::GotoLabel(expr->getLabel()); 384 } 385 386 loc::ConcreteInt makeLoc(const llvm::APSInt &integer) { 387 return loc::ConcreteInt(BasicVals.getValue(integer)); 388 } 389 390 /// Return MemRegionVal on success cast, otherwise return std::nullopt. 391 std::optional<loc::MemRegionVal> 392 getCastedMemRegionVal(const MemRegion *region, QualType type); 393 394 /// Make an SVal that represents the given symbol. This follows the convention 395 /// of representing Loc-type symbols (symbolic pointers and references) 396 /// as Loc values wrapping the symbol rather than as plain symbol values. 397 DefinedSVal makeSymbolVal(SymbolRef Sym) { 398 if (Loc::isLocType(Sym->getType())) 399 return makeLoc(Sym); 400 return nonloc::SymbolVal(Sym); 401 } 402 403 /// Return a memory region for the 'this' object reference. 404 loc::MemRegionVal getCXXThis(const CXXMethodDecl *D, 405 const StackFrameContext *SFC); 406 407 /// Return a memory region for the 'this' object reference. 408 loc::MemRegionVal getCXXThis(const CXXRecordDecl *D, 409 const StackFrameContext *SFC); 410 }; 411 412 SValBuilder* createSimpleSValBuilder(llvm::BumpPtrAllocator &alloc, 413 ASTContext &context, 414 ProgramStateManager &stateMgr); 415 416 } // namespace ento 417 418 } // namespace clang 419 420 #endif // LLVM_CLANG_STATICANALYZER_CORE_PATHSENSITIVE_SVALBUILDER_H 421