1 // SValBuilder.cpp - Basic class for all SValBuilder implementations -*- 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 defines SValBuilder, the base class for all (complete) SValBuilder 11 // implementations. 12 // 13 //===----------------------------------------------------------------------===// 14 15 #include "clang/AST/ExprCXX.h" 16 #include "clang/StaticAnalyzer/Core/PathSensitive/MemRegion.h" 17 #include "clang/StaticAnalyzer/Core/PathSensitive/SVals.h" 18 #include "clang/StaticAnalyzer/Core/PathSensitive/SValBuilder.h" 19 #include "clang/StaticAnalyzer/Core/PathSensitive/ProgramState.h" 20 #include "clang/StaticAnalyzer/Core/PathSensitive/BasicValueFactory.h" 21 22 using namespace clang; 23 using namespace ento; 24 25 //===----------------------------------------------------------------------===// 26 // Basic SVal creation. 27 //===----------------------------------------------------------------------===// 28 29 void SValBuilder::anchor() { } 30 31 DefinedOrUnknownSVal SValBuilder::makeZeroVal(QualType type) { 32 if (Loc::isLocType(type)) 33 return makeNull(); 34 35 if (type->isIntegerType()) 36 return makeIntVal(0, type); 37 38 // FIXME: Handle floats. 39 // FIXME: Handle structs. 40 return UnknownVal(); 41 } 42 43 NonLoc SValBuilder::makeNonLoc(const SymExpr *lhs, BinaryOperator::Opcode op, 44 const llvm::APSInt& rhs, QualType type) { 45 // The Environment ensures we always get a persistent APSInt in 46 // BasicValueFactory, so we don't need to get the APSInt from 47 // BasicValueFactory again. 48 assert(lhs); 49 assert(!Loc::isLocType(type)); 50 return nonloc::SymbolVal(SymMgr.getSymIntExpr(lhs, op, rhs, type)); 51 } 52 53 NonLoc SValBuilder::makeNonLoc(const llvm::APSInt& lhs, 54 BinaryOperator::Opcode op, const SymExpr *rhs, 55 QualType type) { 56 assert(rhs); 57 assert(!Loc::isLocType(type)); 58 return nonloc::SymbolVal(SymMgr.getIntSymExpr(lhs, op, rhs, type)); 59 } 60 61 NonLoc SValBuilder::makeNonLoc(const SymExpr *lhs, BinaryOperator::Opcode op, 62 const SymExpr *rhs, QualType type) { 63 assert(lhs && rhs); 64 assert(haveSameType(lhs->getType(Context), rhs->getType(Context)) == true); 65 assert(!Loc::isLocType(type)); 66 return nonloc::SymbolVal(SymMgr.getSymSymExpr(lhs, op, rhs, type)); 67 } 68 69 NonLoc SValBuilder::makeNonLoc(const SymExpr *operand, 70 QualType fromTy, QualType toTy) { 71 assert(operand); 72 assert(!Loc::isLocType(toTy)); 73 return nonloc::SymbolVal(SymMgr.getCastSymbol(operand, fromTy, toTy)); 74 } 75 76 SVal SValBuilder::convertToArrayIndex(SVal val) { 77 if (val.isUnknownOrUndef()) 78 return val; 79 80 // Common case: we have an appropriately sized integer. 81 if (nonloc::ConcreteInt* CI = dyn_cast<nonloc::ConcreteInt>(&val)) { 82 const llvm::APSInt& I = CI->getValue(); 83 if (I.getBitWidth() == ArrayIndexWidth && I.isSigned()) 84 return val; 85 } 86 87 return evalCastFromNonLoc(cast<NonLoc>(val), ArrayIndexTy); 88 } 89 90 nonloc::ConcreteInt SValBuilder::makeBoolVal(const CXXBoolLiteralExpr *boolean){ 91 return makeTruthVal(boolean->getValue()); 92 } 93 94 DefinedOrUnknownSVal 95 SValBuilder::getRegionValueSymbolVal(const TypedValueRegion* region) { 96 QualType T = region->getValueType(); 97 98 if (!SymbolManager::canSymbolicate(T)) 99 return UnknownVal(); 100 101 SymbolRef sym = SymMgr.getRegionValueSymbol(region); 102 103 if (Loc::isLocType(T)) 104 return loc::MemRegionVal(MemMgr.getSymbolicRegion(sym)); 105 106 return nonloc::SymbolVal(sym); 107 } 108 109 DefinedOrUnknownSVal 110 SValBuilder::getConjuredSymbolVal(const void *symbolTag, 111 const Expr *expr, 112 const LocationContext *LCtx, 113 unsigned count) { 114 QualType T = expr->getType(); 115 return getConjuredSymbolVal(symbolTag, expr, LCtx, T, count); 116 } 117 118 DefinedOrUnknownSVal 119 SValBuilder::getConjuredSymbolVal(const void *symbolTag, 120 const Expr *expr, 121 const LocationContext *LCtx, 122 QualType type, 123 unsigned count) { 124 if (!SymbolManager::canSymbolicate(type)) 125 return UnknownVal(); 126 127 SymbolRef sym = SymMgr.getConjuredSymbol(expr, LCtx, type, count, symbolTag); 128 129 if (Loc::isLocType(type)) 130 return loc::MemRegionVal(MemMgr.getSymbolicRegion(sym)); 131 132 return nonloc::SymbolVal(sym); 133 } 134 135 136 DefinedOrUnknownSVal 137 SValBuilder::getConjuredSymbolVal(const Stmt *stmt, 138 const LocationContext *LCtx, 139 QualType type, 140 unsigned visitCount) { 141 if (!SymbolManager::canSymbolicate(type)) 142 return UnknownVal(); 143 144 SymbolRef sym = SymMgr.getConjuredSymbol(stmt, LCtx, type, visitCount); 145 146 if (Loc::isLocType(type)) 147 return loc::MemRegionVal(MemMgr.getSymbolicRegion(sym)); 148 149 return nonloc::SymbolVal(sym); 150 } 151 152 DefinedSVal SValBuilder::getMetadataSymbolVal(const void *symbolTag, 153 const MemRegion *region, 154 const Expr *expr, QualType type, 155 unsigned count) { 156 assert(SymbolManager::canSymbolicate(type) && "Invalid metadata symbol type"); 157 158 SymbolRef sym = 159 SymMgr.getMetadataSymbol(region, expr, type, count, symbolTag); 160 161 if (Loc::isLocType(type)) 162 return loc::MemRegionVal(MemMgr.getSymbolicRegion(sym)); 163 164 return nonloc::SymbolVal(sym); 165 } 166 167 DefinedOrUnknownSVal 168 SValBuilder::getDerivedRegionValueSymbolVal(SymbolRef parentSymbol, 169 const TypedValueRegion *region) { 170 QualType T = region->getValueType(); 171 172 if (!SymbolManager::canSymbolicate(T)) 173 return UnknownVal(); 174 175 SymbolRef sym = SymMgr.getDerivedSymbol(parentSymbol, region); 176 177 if (Loc::isLocType(T)) 178 return loc::MemRegionVal(MemMgr.getSymbolicRegion(sym)); 179 180 return nonloc::SymbolVal(sym); 181 } 182 183 DefinedSVal SValBuilder::getFunctionPointer(const FunctionDecl *func) { 184 return loc::MemRegionVal(MemMgr.getFunctionTextRegion(func)); 185 } 186 187 DefinedSVal SValBuilder::getBlockPointer(const BlockDecl *block, 188 CanQualType locTy, 189 const LocationContext *locContext) { 190 const BlockTextRegion *BC = 191 MemMgr.getBlockTextRegion(block, locTy, locContext->getAnalysisDeclContext()); 192 const BlockDataRegion *BD = MemMgr.getBlockDataRegion(BC, locContext); 193 return loc::MemRegionVal(BD); 194 } 195 196 //===----------------------------------------------------------------------===// 197 198 SVal SValBuilder::makeGenericVal(ProgramStateRef State, 199 BinaryOperator::Opcode Op, 200 NonLoc LHS, NonLoc RHS, 201 QualType ResultTy) { 202 // If operands are tainted, create a symbol to ensure that we propagate taint. 203 if (State->isTainted(RHS) || State->isTainted(LHS)) { 204 const SymExpr *symLHS; 205 const SymExpr *symRHS; 206 207 if (const nonloc::ConcreteInt *rInt = dyn_cast<nonloc::ConcreteInt>(&RHS)) { 208 symLHS = LHS.getAsSymExpr(); 209 return makeNonLoc(symLHS, Op, rInt->getValue(), ResultTy); 210 } 211 212 if (const nonloc::ConcreteInt *lInt = dyn_cast<nonloc::ConcreteInt>(&LHS)) { 213 symRHS = RHS.getAsSymExpr(); 214 return makeNonLoc(lInt->getValue(), Op, symRHS, ResultTy); 215 } 216 217 symLHS = LHS.getAsSymExpr(); 218 symRHS = RHS.getAsSymExpr(); 219 return makeNonLoc(symLHS, Op, symRHS, ResultTy); 220 } 221 return UnknownVal(); 222 } 223 224 225 SVal SValBuilder::evalBinOp(ProgramStateRef state, BinaryOperator::Opcode op, 226 SVal lhs, SVal rhs, QualType type) { 227 228 if (lhs.isUndef() || rhs.isUndef()) 229 return UndefinedVal(); 230 231 if (lhs.isUnknown() || rhs.isUnknown()) 232 return UnknownVal(); 233 234 if (isa<Loc>(lhs)) { 235 if (isa<Loc>(rhs)) 236 return evalBinOpLL(state, op, cast<Loc>(lhs), cast<Loc>(rhs), type); 237 238 return evalBinOpLN(state, op, cast<Loc>(lhs), cast<NonLoc>(rhs), type); 239 } 240 241 if (isa<Loc>(rhs)) { 242 // Support pointer arithmetic where the addend is on the left 243 // and the pointer on the right. 244 assert(op == BO_Add); 245 246 // Commute the operands. 247 return evalBinOpLN(state, op, cast<Loc>(rhs), cast<NonLoc>(lhs), type); 248 } 249 250 return evalBinOpNN(state, op, cast<NonLoc>(lhs), cast<NonLoc>(rhs), type); 251 } 252 253 DefinedOrUnknownSVal SValBuilder::evalEQ(ProgramStateRef state, 254 DefinedOrUnknownSVal lhs, 255 DefinedOrUnknownSVal rhs) { 256 return cast<DefinedOrUnknownSVal>(evalBinOp(state, BO_EQ, lhs, rhs, 257 Context.IntTy)); 258 } 259 260 /// Recursively check if the pointer types are equal modulo const, volatile, 261 /// and restrict qualifiers. Assumes the input types are canonical. 262 /// TODO: This is based off of code in SemaCast; can we reuse it. 263 static bool haveSimilarTypes(ASTContext &Context, QualType T1, 264 QualType T2) { 265 while (Context.UnwrapSimilarPointerTypes(T1, T2)) { 266 Qualifiers Quals1, Quals2; 267 T1 = Context.getUnqualifiedArrayType(T1, Quals1); 268 T2 = Context.getUnqualifiedArrayType(T2, Quals2); 269 270 // Make sure that non cvr-qualifiers the other qualifiers (e.g., address 271 // spaces) are identical. 272 Quals1.removeCVRQualifiers(); 273 Quals2.removeCVRQualifiers(); 274 if (Quals1 != Quals2) 275 return false; 276 } 277 278 if (T1 != T2) 279 return false; 280 281 return true; 282 } 283 284 // FIXME: should rewrite according to the cast kind. 285 SVal SValBuilder::evalCast(SVal val, QualType castTy, QualType originalTy) { 286 castTy = Context.getCanonicalType(castTy); 287 originalTy = Context.getCanonicalType(originalTy); 288 if (val.isUnknownOrUndef() || castTy == originalTy) 289 return val; 290 291 // For const casts, just propagate the value. 292 if (!castTy->isVariableArrayType() && !originalTy->isVariableArrayType()) 293 if (haveSimilarTypes(Context, Context.getPointerType(castTy), 294 Context.getPointerType(originalTy))) 295 return val; 296 297 // Check for casts from pointers to integers. 298 if (castTy->isIntegerType() && Loc::isLocType(originalTy)) 299 return evalCastFromLoc(cast<Loc>(val), castTy); 300 301 // Check for casts from integers to pointers. 302 if (Loc::isLocType(castTy) && originalTy->isIntegerType()) { 303 if (nonloc::LocAsInteger *LV = dyn_cast<nonloc::LocAsInteger>(&val)) { 304 if (const MemRegion *R = LV->getLoc().getAsRegion()) { 305 StoreManager &storeMgr = StateMgr.getStoreManager(); 306 R = storeMgr.castRegion(R, castTy); 307 return R ? SVal(loc::MemRegionVal(R)) : UnknownVal(); 308 } 309 return LV->getLoc(); 310 } 311 return dispatchCast(val, castTy); 312 } 313 314 // Just pass through function and block pointers. 315 if (originalTy->isBlockPointerType() || originalTy->isFunctionPointerType()) { 316 assert(Loc::isLocType(castTy)); 317 return val; 318 } 319 320 // Check for casts from array type to another type. 321 if (originalTy->isArrayType()) { 322 // We will always decay to a pointer. 323 val = StateMgr.ArrayToPointer(cast<Loc>(val)); 324 325 // Are we casting from an array to a pointer? If so just pass on 326 // the decayed value. 327 if (castTy->isPointerType()) 328 return val; 329 330 // Are we casting from an array to an integer? If so, cast the decayed 331 // pointer value to an integer. 332 assert(castTy->isIntegerType()); 333 334 // FIXME: Keep these here for now in case we decide soon that we 335 // need the original decayed type. 336 // QualType elemTy = cast<ArrayType>(originalTy)->getElementType(); 337 // QualType pointerTy = C.getPointerType(elemTy); 338 return evalCastFromLoc(cast<Loc>(val), castTy); 339 } 340 341 // Check for casts from a region to a specific type. 342 if (const MemRegion *R = val.getAsRegion()) { 343 // FIXME: We should handle the case where we strip off view layers to get 344 // to a desugared type. 345 346 if (!Loc::isLocType(castTy)) { 347 // FIXME: There can be gross cases where one casts the result of a function 348 // (that returns a pointer) to some other value that happens to fit 349 // within that pointer value. We currently have no good way to 350 // model such operations. When this happens, the underlying operation 351 // is that the caller is reasoning about bits. Conceptually we are 352 // layering a "view" of a location on top of those bits. Perhaps 353 // we need to be more lazy about mutual possible views, even on an 354 // SVal? This may be necessary for bit-level reasoning as well. 355 return UnknownVal(); 356 } 357 358 // We get a symbolic function pointer for a dereference of a function 359 // pointer, but it is of function type. Example: 360 361 // struct FPRec { 362 // void (*my_func)(int * x); 363 // }; 364 // 365 // int bar(int x); 366 // 367 // int f1_a(struct FPRec* foo) { 368 // int x; 369 // (*foo->my_func)(&x); 370 // return bar(x)+1; // no-warning 371 // } 372 373 assert(Loc::isLocType(originalTy) || originalTy->isFunctionType() || 374 originalTy->isBlockPointerType() || castTy->isReferenceType()); 375 376 StoreManager &storeMgr = StateMgr.getStoreManager(); 377 378 // Delegate to store manager to get the result of casting a region to a 379 // different type. If the MemRegion* returned is NULL, this expression 380 // Evaluates to UnknownVal. 381 R = storeMgr.castRegion(R, castTy); 382 return R ? SVal(loc::MemRegionVal(R)) : UnknownVal(); 383 } 384 385 return dispatchCast(val, castTy); 386 } 387