1 //=-- ExprEngineC.cpp - ExprEngine support for C expressions ----*- 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 ExprEngine's support for C expressions. 11 // 12 //===----------------------------------------------------------------------===// 13 14 #include "clang/StaticAnalyzer/Core/CheckerManager.h" 15 #include "clang/StaticAnalyzer/Core/PathSensitive/ExprEngine.h" 16 17 using namespace clang; 18 using namespace ento; 19 using llvm::APSInt; 20 21 void ExprEngine::VisitBinaryOperator(const BinaryOperator* B, 22 ExplodedNode *Pred, 23 ExplodedNodeSet &Dst) { 24 25 Expr *LHS = B->getLHS()->IgnoreParens(); 26 Expr *RHS = B->getRHS()->IgnoreParens(); 27 28 // FIXME: Prechecks eventually go in ::Visit(). 29 ExplodedNodeSet CheckedSet; 30 ExplodedNodeSet Tmp2; 31 getCheckerManager().runCheckersForPreStmt(CheckedSet, Pred, B, *this); 32 33 // With both the LHS and RHS evaluated, process the operation itself. 34 for (ExplodedNodeSet::iterator it=CheckedSet.begin(), ei=CheckedSet.end(); 35 it != ei; ++it) { 36 37 ProgramStateRef state = (*it)->getState(); 38 const LocationContext *LCtx = (*it)->getLocationContext(); 39 SVal LeftV = state->getSVal(LHS, LCtx); 40 SVal RightV = state->getSVal(RHS, LCtx); 41 42 BinaryOperator::Opcode Op = B->getOpcode(); 43 44 if (Op == BO_Assign) { 45 // EXPERIMENTAL: "Conjured" symbols. 46 // FIXME: Handle structs. 47 if (RightV.isUnknown()) { 48 unsigned Count = currentBuilderContext->getCurrentBlockCount(); 49 RightV = svalBuilder.getConjuredSymbolVal(NULL, B->getRHS(), LCtx, Count); 50 } 51 // Simulate the effects of a "store": bind the value of the RHS 52 // to the L-Value represented by the LHS. 53 SVal ExprVal = B->isLValue() ? LeftV : RightV; 54 evalStore(Tmp2, B, LHS, *it, state->BindExpr(B, LCtx, ExprVal), 55 LeftV, RightV); 56 continue; 57 } 58 59 if (!B->isAssignmentOp()) { 60 StmtNodeBuilder Bldr(*it, Tmp2, *currentBuilderContext); 61 // Process non-assignments except commas or short-circuited 62 // logical expressions (LAnd and LOr). 63 SVal Result = evalBinOp(state, Op, LeftV, RightV, B->getType()); 64 if (Result.isUnknown()) { 65 Bldr.generateNode(B, *it, state); 66 continue; 67 } 68 69 state = state->BindExpr(B, LCtx, Result); 70 Bldr.generateNode(B, *it, state); 71 continue; 72 } 73 74 assert (B->isCompoundAssignmentOp()); 75 76 switch (Op) { 77 default: 78 llvm_unreachable("Invalid opcode for compound assignment."); 79 case BO_MulAssign: Op = BO_Mul; break; 80 case BO_DivAssign: Op = BO_Div; break; 81 case BO_RemAssign: Op = BO_Rem; break; 82 case BO_AddAssign: Op = BO_Add; break; 83 case BO_SubAssign: Op = BO_Sub; break; 84 case BO_ShlAssign: Op = BO_Shl; break; 85 case BO_ShrAssign: Op = BO_Shr; break; 86 case BO_AndAssign: Op = BO_And; break; 87 case BO_XorAssign: Op = BO_Xor; break; 88 case BO_OrAssign: Op = BO_Or; break; 89 } 90 91 // Perform a load (the LHS). This performs the checks for 92 // null dereferences, and so on. 93 ExplodedNodeSet Tmp; 94 SVal location = LeftV; 95 evalLoad(Tmp, B, LHS, *it, state, location); 96 97 for (ExplodedNodeSet::iterator I = Tmp.begin(), E = Tmp.end(); I != E; 98 ++I) { 99 100 state = (*I)->getState(); 101 const LocationContext *LCtx = (*I)->getLocationContext(); 102 SVal V = state->getSVal(LHS, LCtx); 103 104 // Get the computation type. 105 QualType CTy = 106 cast<CompoundAssignOperator>(B)->getComputationResultType(); 107 CTy = getContext().getCanonicalType(CTy); 108 109 QualType CLHSTy = 110 cast<CompoundAssignOperator>(B)->getComputationLHSType(); 111 CLHSTy = getContext().getCanonicalType(CLHSTy); 112 113 QualType LTy = getContext().getCanonicalType(LHS->getType()); 114 115 // Promote LHS. 116 V = svalBuilder.evalCast(V, CLHSTy, LTy); 117 118 // Compute the result of the operation. 119 SVal Result = svalBuilder.evalCast(evalBinOp(state, Op, V, RightV, CTy), 120 B->getType(), CTy); 121 122 // EXPERIMENTAL: "Conjured" symbols. 123 // FIXME: Handle structs. 124 125 SVal LHSVal; 126 127 if (Result.isUnknown()) { 128 129 unsigned Count = currentBuilderContext->getCurrentBlockCount(); 130 131 // The symbolic value is actually for the type of the left-hand side 132 // expression, not the computation type, as this is the value the 133 // LValue on the LHS will bind to. 134 LHSVal = svalBuilder.getConjuredSymbolVal(NULL, B->getRHS(), LCtx, 135 LTy, Count); 136 137 // However, we need to convert the symbol to the computation type. 138 Result = svalBuilder.evalCast(LHSVal, CTy, LTy); 139 } 140 else { 141 // The left-hand side may bind to a different value then the 142 // computation type. 143 LHSVal = svalBuilder.evalCast(Result, LTy, CTy); 144 } 145 146 // In C++, assignment and compound assignment operators return an 147 // lvalue. 148 if (B->isLValue()) 149 state = state->BindExpr(B, LCtx, location); 150 else 151 state = state->BindExpr(B, LCtx, Result); 152 153 evalStore(Tmp2, B, LHS, *I, state, location, LHSVal); 154 } 155 } 156 157 // FIXME: postvisits eventually go in ::Visit() 158 getCheckerManager().runCheckersForPostStmt(Dst, Tmp2, B, *this); 159 } 160 161 void ExprEngine::VisitBlockExpr(const BlockExpr *BE, ExplodedNode *Pred, 162 ExplodedNodeSet &Dst) { 163 164 CanQualType T = getContext().getCanonicalType(BE->getType()); 165 SVal V = svalBuilder.getBlockPointer(BE->getBlockDecl(), T, 166 Pred->getLocationContext()); 167 168 ExplodedNodeSet Tmp; 169 StmtNodeBuilder Bldr(Pred, Tmp, *currentBuilderContext); 170 Bldr.generateNode(BE, Pred, 171 Pred->getState()->BindExpr(BE, Pred->getLocationContext(), 172 V), 173 false, 0, 174 ProgramPoint::PostLValueKind); 175 176 // FIXME: Move all post/pre visits to ::Visit(). 177 getCheckerManager().runCheckersForPostStmt(Dst, Tmp, BE, *this); 178 } 179 180 void ExprEngine::VisitCast(const CastExpr *CastE, const Expr *Ex, 181 ExplodedNode *Pred, ExplodedNodeSet &Dst) { 182 183 ExplodedNodeSet dstPreStmt; 184 getCheckerManager().runCheckersForPreStmt(dstPreStmt, Pred, CastE, *this); 185 186 if (CastE->getCastKind() == CK_LValueToRValue) { 187 for (ExplodedNodeSet::iterator I = dstPreStmt.begin(), E = dstPreStmt.end(); 188 I!=E; ++I) { 189 ExplodedNode *subExprNode = *I; 190 ProgramStateRef state = subExprNode->getState(); 191 const LocationContext *LCtx = subExprNode->getLocationContext(); 192 evalLoad(Dst, CastE, CastE, subExprNode, state, state->getSVal(Ex, LCtx)); 193 } 194 return; 195 } 196 197 // All other casts. 198 QualType T = CastE->getType(); 199 QualType ExTy = Ex->getType(); 200 201 if (const ExplicitCastExpr *ExCast=dyn_cast_or_null<ExplicitCastExpr>(CastE)) 202 T = ExCast->getTypeAsWritten(); 203 204 StmtNodeBuilder Bldr(dstPreStmt, Dst, *currentBuilderContext); 205 for (ExplodedNodeSet::iterator I = dstPreStmt.begin(), E = dstPreStmt.end(); 206 I != E; ++I) { 207 208 Pred = *I; 209 210 switch (CastE->getCastKind()) { 211 case CK_LValueToRValue: 212 llvm_unreachable("LValueToRValue casts handled earlier."); 213 case CK_ToVoid: 214 continue; 215 // The analyzer doesn't do anything special with these casts, 216 // since it understands retain/release semantics already. 217 case CK_ARCProduceObject: 218 case CK_ARCConsumeObject: 219 case CK_ARCReclaimReturnedObject: 220 case CK_ARCExtendBlockObject: // Fall-through. 221 case CK_CopyAndAutoreleaseBlockObject: 222 // The analyser can ignore atomic casts for now, although some future 223 // checkers may want to make certain that you're not modifying the same 224 // value through atomic and nonatomic pointers. 225 case CK_AtomicToNonAtomic: 226 case CK_NonAtomicToAtomic: 227 // True no-ops. 228 case CK_NoOp: 229 case CK_FunctionToPointerDecay: { 230 // Copy the SVal of Ex to CastE. 231 ProgramStateRef state = Pred->getState(); 232 const LocationContext *LCtx = Pred->getLocationContext(); 233 SVal V = state->getSVal(Ex, LCtx); 234 state = state->BindExpr(CastE, LCtx, V); 235 Bldr.generateNode(CastE, Pred, state); 236 continue; 237 } 238 case CK_Dependent: 239 case CK_ArrayToPointerDecay: 240 case CK_BitCast: 241 case CK_LValueBitCast: 242 case CK_IntegralCast: 243 case CK_NullToPointer: 244 case CK_IntegralToPointer: 245 case CK_PointerToIntegral: 246 case CK_PointerToBoolean: 247 case CK_IntegralToBoolean: 248 case CK_IntegralToFloating: 249 case CK_FloatingToIntegral: 250 case CK_FloatingToBoolean: 251 case CK_FloatingCast: 252 case CK_FloatingRealToComplex: 253 case CK_FloatingComplexToReal: 254 case CK_FloatingComplexToBoolean: 255 case CK_FloatingComplexCast: 256 case CK_FloatingComplexToIntegralComplex: 257 case CK_IntegralRealToComplex: 258 case CK_IntegralComplexToReal: 259 case CK_IntegralComplexToBoolean: 260 case CK_IntegralComplexCast: 261 case CK_IntegralComplexToFloatingComplex: 262 case CK_CPointerToObjCPointerCast: 263 case CK_BlockPointerToObjCPointerCast: 264 case CK_AnyPointerToBlockPointerCast: 265 case CK_ObjCObjectLValueCast: { 266 // Delegate to SValBuilder to process. 267 ProgramStateRef state = Pred->getState(); 268 const LocationContext *LCtx = Pred->getLocationContext(); 269 SVal V = state->getSVal(Ex, LCtx); 270 V = svalBuilder.evalCast(V, T, ExTy); 271 state = state->BindExpr(CastE, LCtx, V); 272 Bldr.generateNode(CastE, Pred, state); 273 continue; 274 } 275 case CK_DerivedToBase: 276 case CK_UncheckedDerivedToBase: { 277 // For DerivedToBase cast, delegate to the store manager. 278 ProgramStateRef state = Pred->getState(); 279 const LocationContext *LCtx = Pred->getLocationContext(); 280 SVal val = state->getSVal(Ex, LCtx); 281 val = getStoreManager().evalDerivedToBase(val, T); 282 state = state->BindExpr(CastE, LCtx, val); 283 Bldr.generateNode(CastE, Pred, state); 284 continue; 285 } 286 // Handle C++ dyn_cast. 287 case CK_Dynamic: { 288 ProgramStateRef state = Pred->getState(); 289 const LocationContext *LCtx = Pred->getLocationContext(); 290 SVal val = state->getSVal(Ex, LCtx); 291 292 // Compute the type of the result. 293 QualType resultType = CastE->getType(); 294 if (CastE->isLValue()) 295 resultType = getContext().getPointerType(resultType); 296 297 bool Failed = false; 298 299 // Check if the value being cast evaluates to 0. 300 if (val.isZeroConstant()) 301 Failed = true; 302 // Else, evaluate the cast. 303 else 304 val = getStoreManager().evalDynamicCast(val, T, Failed); 305 306 if (Failed) { 307 if (T->isReferenceType()) { 308 // A bad_cast exception is thrown if input value is a reference. 309 // Currently, we model this, by generating a sink. 310 Bldr.generateNode(CastE, Pred, state, true); 311 continue; 312 } else { 313 // If the cast fails on a pointer, bind to 0. 314 state = state->BindExpr(CastE, LCtx, svalBuilder.makeNull()); 315 } 316 } else { 317 // If we don't know if the cast succeeded, conjure a new symbol. 318 if (val.isUnknown()) { 319 DefinedOrUnknownSVal NewSym = svalBuilder.getConjuredSymbolVal(NULL, 320 CastE, LCtx, resultType, 321 currentBuilderContext->getCurrentBlockCount()); 322 state = state->BindExpr(CastE, LCtx, NewSym); 323 } else 324 // Else, bind to the derived region value. 325 state = state->BindExpr(CastE, LCtx, val); 326 } 327 Bldr.generateNode(CastE, Pred, state); 328 continue; 329 } 330 // Various C++ casts that are not handled yet. 331 case CK_ToUnion: 332 case CK_BaseToDerived: 333 case CK_NullToMemberPointer: 334 case CK_BaseToDerivedMemberPointer: 335 case CK_DerivedToBaseMemberPointer: 336 case CK_ReinterpretMemberPointer: 337 case CK_UserDefinedConversion: 338 case CK_ConstructorConversion: 339 case CK_VectorSplat: 340 case CK_MemberPointerToBoolean: { 341 // Recover some path-sensitivty by conjuring a new value. 342 QualType resultType = CastE->getType(); 343 if (CastE->isLValue()) 344 resultType = getContext().getPointerType(resultType); 345 const LocationContext *LCtx = Pred->getLocationContext(); 346 SVal result = svalBuilder.getConjuredSymbolVal(NULL, CastE, LCtx, 347 resultType, currentBuilderContext->getCurrentBlockCount()); 348 ProgramStateRef state = Pred->getState()->BindExpr(CastE, LCtx, 349 result); 350 Bldr.generateNode(CastE, Pred, state); 351 continue; 352 } 353 } 354 } 355 } 356 357 void ExprEngine::VisitCompoundLiteralExpr(const CompoundLiteralExpr *CL, 358 ExplodedNode *Pred, 359 ExplodedNodeSet &Dst) { 360 StmtNodeBuilder B(Pred, Dst, *currentBuilderContext); 361 362 const InitListExpr *ILE 363 = cast<InitListExpr>(CL->getInitializer()->IgnoreParens()); 364 365 ProgramStateRef state = Pred->getState(); 366 SVal ILV = state->getSVal(ILE, Pred->getLocationContext()); 367 const LocationContext *LC = Pred->getLocationContext(); 368 state = state->bindCompoundLiteral(CL, LC, ILV); 369 370 if (CL->isLValue()) 371 B.generateNode(CL, Pred, state->BindExpr(CL, LC, state->getLValue(CL, LC))); 372 else 373 B.generateNode(CL, Pred, state->BindExpr(CL, LC, ILV)); 374 } 375 376 void ExprEngine::VisitDeclStmt(const DeclStmt *DS, ExplodedNode *Pred, 377 ExplodedNodeSet &Dst) { 378 379 // FIXME: static variables may have an initializer, but the second 380 // time a function is called those values may not be current. 381 // This may need to be reflected in the CFG. 382 383 // Assumption: The CFG has one DeclStmt per Decl. 384 const Decl *D = *DS->decl_begin(); 385 386 if (!D || !isa<VarDecl>(D)) { 387 //TODO:AZ: remove explicit insertion after refactoring is done. 388 Dst.insert(Pred); 389 return; 390 } 391 392 // FIXME: all pre/post visits should eventually be handled by ::Visit(). 393 ExplodedNodeSet dstPreVisit; 394 getCheckerManager().runCheckersForPreStmt(dstPreVisit, Pred, DS, *this); 395 396 StmtNodeBuilder B(dstPreVisit, Dst, *currentBuilderContext); 397 const VarDecl *VD = dyn_cast<VarDecl>(D); 398 for (ExplodedNodeSet::iterator I = dstPreVisit.begin(), E = dstPreVisit.end(); 399 I!=E; ++I) { 400 ExplodedNode *N = *I; 401 ProgramStateRef state = N->getState(); 402 403 // Decls without InitExpr are not initialized explicitly. 404 const LocationContext *LC = N->getLocationContext(); 405 406 if (const Expr *InitEx = VD->getInit()) { 407 SVal InitVal = state->getSVal(InitEx, Pred->getLocationContext()); 408 409 // We bound the temp obj region to the CXXConstructExpr. Now recover 410 // the lazy compound value when the variable is not a reference. 411 if (AMgr.getLangOpts().CPlusPlus && VD->getType()->isRecordType() && 412 !VD->getType()->isReferenceType() && isa<loc::MemRegionVal>(InitVal)){ 413 InitVal = state->getSVal(cast<loc::MemRegionVal>(InitVal).getRegion()); 414 assert(isa<nonloc::LazyCompoundVal>(InitVal)); 415 } 416 417 // Recover some path-sensitivity if a scalar value evaluated to 418 // UnknownVal. 419 if (InitVal.isUnknown()) { 420 QualType Ty = InitEx->getType(); 421 if (InitEx->isLValue()) { 422 Ty = getContext().getPointerType(Ty); 423 } 424 425 InitVal = svalBuilder.getConjuredSymbolVal(NULL, InitEx, LC, Ty, 426 currentBuilderContext->getCurrentBlockCount()); 427 } 428 B.takeNodes(N); 429 ExplodedNodeSet Dst2; 430 evalBind(Dst2, DS, N, state->getLValue(VD, LC), InitVal, true); 431 B.addNodes(Dst2); 432 } 433 else { 434 B.generateNode(DS, N,state->bindDeclWithNoInit(state->getRegion(VD, LC))); 435 } 436 } 437 } 438 439 void ExprEngine::VisitLogicalExpr(const BinaryOperator* B, ExplodedNode *Pred, 440 ExplodedNodeSet &Dst) { 441 assert(B->getOpcode() == BO_LAnd || 442 B->getOpcode() == BO_LOr); 443 444 StmtNodeBuilder Bldr(Pred, Dst, *currentBuilderContext); 445 ProgramStateRef state = Pred->getState(); 446 const LocationContext *LCtx = Pred->getLocationContext(); 447 SVal X = state->getSVal(B, LCtx); 448 assert(X.isUndef()); 449 450 const Expr *Ex = (const Expr*) cast<UndefinedVal>(X).getData(); 451 assert(Ex); 452 453 if (Ex == B->getRHS()) { 454 X = state->getSVal(Ex, LCtx); 455 456 // Handle undefined values. 457 if (X.isUndef()) { 458 Bldr.generateNode(B, Pred, state->BindExpr(B, LCtx, X)); 459 return; 460 } 461 462 DefinedOrUnknownSVal XD = cast<DefinedOrUnknownSVal>(X); 463 464 // We took the RHS. Because the value of the '&&' or '||' expression must 465 // evaluate to 0 or 1, we must assume the value of the RHS evaluates to 0 466 // or 1. Alternatively, we could take a lazy approach, and calculate this 467 // value later when necessary. We don't have the machinery in place for 468 // this right now, and since most logical expressions are used for branches, 469 // the payoff is not likely to be large. Instead, we do eager evaluation. 470 if (ProgramStateRef newState = state->assume(XD, true)) 471 Bldr.generateNode(B, Pred, 472 newState->BindExpr(B, LCtx, 473 svalBuilder.makeIntVal(1U, B->getType()))); 474 475 if (ProgramStateRef newState = state->assume(XD, false)) 476 Bldr.generateNode(B, Pred, 477 newState->BindExpr(B, LCtx, 478 svalBuilder.makeIntVal(0U, B->getType()))); 479 } 480 else { 481 // We took the LHS expression. Depending on whether we are '&&' or 482 // '||' we know what the value of the expression is via properties of 483 // the short-circuiting. 484 X = svalBuilder.makeIntVal(B->getOpcode() == BO_LAnd ? 0U : 1U, 485 B->getType()); 486 Bldr.generateNode(B, Pred, state->BindExpr(B, LCtx, X)); 487 } 488 } 489 490 void ExprEngine::VisitInitListExpr(const InitListExpr *IE, 491 ExplodedNode *Pred, 492 ExplodedNodeSet &Dst) { 493 StmtNodeBuilder B(Pred, Dst, *currentBuilderContext); 494 495 ProgramStateRef state = Pred->getState(); 496 const LocationContext *LCtx = Pred->getLocationContext(); 497 QualType T = getContext().getCanonicalType(IE->getType()); 498 unsigned NumInitElements = IE->getNumInits(); 499 500 if (T->isArrayType() || T->isRecordType() || T->isVectorType()) { 501 llvm::ImmutableList<SVal> vals = getBasicVals().getEmptySValList(); 502 503 // Handle base case where the initializer has no elements. 504 // e.g: static int* myArray[] = {}; 505 if (NumInitElements == 0) { 506 SVal V = svalBuilder.makeCompoundVal(T, vals); 507 B.generateNode(IE, Pred, state->BindExpr(IE, LCtx, V)); 508 return; 509 } 510 511 for (InitListExpr::const_reverse_iterator it = IE->rbegin(), 512 ei = IE->rend(); it != ei; ++it) { 513 vals = getBasicVals().consVals(state->getSVal(cast<Expr>(*it), LCtx), 514 vals); 515 } 516 517 B.generateNode(IE, Pred, 518 state->BindExpr(IE, LCtx, 519 svalBuilder.makeCompoundVal(T, vals))); 520 return; 521 } 522 523 if (Loc::isLocType(T) || T->isIntegerType()) { 524 assert(IE->getNumInits() == 1); 525 const Expr *initEx = IE->getInit(0); 526 B.generateNode(IE, Pred, state->BindExpr(IE, LCtx, 527 state->getSVal(initEx, LCtx))); 528 return; 529 } 530 531 llvm_unreachable("unprocessed InitListExpr type"); 532 } 533 534 void ExprEngine::VisitGuardedExpr(const Expr *Ex, 535 const Expr *L, 536 const Expr *R, 537 ExplodedNode *Pred, 538 ExplodedNodeSet &Dst) { 539 StmtNodeBuilder B(Pred, Dst, *currentBuilderContext); 540 541 ProgramStateRef state = Pred->getState(); 542 const LocationContext *LCtx = Pred->getLocationContext(); 543 SVal X = state->getSVal(Ex, LCtx); 544 assert (X.isUndef()); 545 const Expr *SE = (Expr*) cast<UndefinedVal>(X).getData(); 546 assert(SE); 547 X = state->getSVal(SE, LCtx); 548 549 // Make sure that we invalidate the previous binding. 550 B.generateNode(Ex, Pred, state->BindExpr(Ex, LCtx, X, true)); 551 } 552 553 void ExprEngine:: 554 VisitOffsetOfExpr(const OffsetOfExpr *OOE, 555 ExplodedNode *Pred, ExplodedNodeSet &Dst) { 556 StmtNodeBuilder B(Pred, Dst, *currentBuilderContext); 557 APSInt IV; 558 if (OOE->EvaluateAsInt(IV, getContext())) { 559 assert(IV.getBitWidth() == getContext().getTypeSize(OOE->getType())); 560 assert(OOE->getType()->isIntegerType()); 561 assert(IV.isSigned() == OOE->getType()->isSignedIntegerOrEnumerationType()); 562 SVal X = svalBuilder.makeIntVal(IV); 563 B.generateNode(OOE, Pred, 564 Pred->getState()->BindExpr(OOE, Pred->getLocationContext(), 565 X)); 566 } 567 // FIXME: Handle the case where __builtin_offsetof is not a constant. 568 } 569 570 571 void ExprEngine:: 572 VisitUnaryExprOrTypeTraitExpr(const UnaryExprOrTypeTraitExpr *Ex, 573 ExplodedNode *Pred, 574 ExplodedNodeSet &Dst) { 575 StmtNodeBuilder Bldr(Pred, Dst, *currentBuilderContext); 576 577 QualType T = Ex->getTypeOfArgument(); 578 579 if (Ex->getKind() == UETT_SizeOf) { 580 if (!T->isIncompleteType() && !T->isConstantSizeType()) { 581 assert(T->isVariableArrayType() && "Unknown non-constant-sized type."); 582 583 // FIXME: Add support for VLA type arguments and VLA expressions. 584 // When that happens, we should probably refactor VLASizeChecker's code. 585 return; 586 } 587 else if (T->getAs<ObjCObjectType>()) { 588 // Some code tries to take the sizeof an ObjCObjectType, relying that 589 // the compiler has laid out its representation. Just report Unknown 590 // for these. 591 return; 592 } 593 } 594 595 APSInt Value = Ex->EvaluateKnownConstInt(getContext()); 596 CharUnits amt = CharUnits::fromQuantity(Value.getZExtValue()); 597 598 ProgramStateRef state = Pred->getState(); 599 state = state->BindExpr(Ex, Pred->getLocationContext(), 600 svalBuilder.makeIntVal(amt.getQuantity(), 601 Ex->getType())); 602 Bldr.generateNode(Ex, Pred, state); 603 } 604 605 void ExprEngine::VisitUnaryOperator(const UnaryOperator* U, 606 ExplodedNode *Pred, 607 ExplodedNodeSet &Dst) { 608 StmtNodeBuilder Bldr(Pred, Dst, *currentBuilderContext); 609 switch (U->getOpcode()) { 610 default: { 611 Bldr.takeNodes(Pred); 612 ExplodedNodeSet Tmp; 613 VisitIncrementDecrementOperator(U, Pred, Tmp); 614 Bldr.addNodes(Tmp); 615 } 616 break; 617 case UO_Real: { 618 const Expr *Ex = U->getSubExpr()->IgnoreParens(); 619 620 // FIXME: We don't have complex SValues yet. 621 if (Ex->getType()->isAnyComplexType()) { 622 // Just report "Unknown." 623 break; 624 } 625 626 // For all other types, UO_Real is an identity operation. 627 assert (U->getType() == Ex->getType()); 628 ProgramStateRef state = Pred->getState(); 629 const LocationContext *LCtx = Pred->getLocationContext(); 630 Bldr.generateNode(U, Pred, state->BindExpr(U, LCtx, 631 state->getSVal(Ex, LCtx))); 632 break; 633 } 634 635 case UO_Imag: { 636 const Expr *Ex = U->getSubExpr()->IgnoreParens(); 637 // FIXME: We don't have complex SValues yet. 638 if (Ex->getType()->isAnyComplexType()) { 639 // Just report "Unknown." 640 break; 641 } 642 // For all other types, UO_Imag returns 0. 643 ProgramStateRef state = Pred->getState(); 644 const LocationContext *LCtx = Pred->getLocationContext(); 645 SVal X = svalBuilder.makeZeroVal(Ex->getType()); 646 Bldr.generateNode(U, Pred, state->BindExpr(U, LCtx, X)); 647 break; 648 } 649 650 case UO_Plus: 651 assert(!U->isLValue()); 652 // FALL-THROUGH. 653 case UO_Deref: 654 case UO_AddrOf: 655 case UO_Extension: { 656 // FIXME: We can probably just have some magic in Environment::getSVal() 657 // that propagates values, instead of creating a new node here. 658 // 659 // Unary "+" is a no-op, similar to a parentheses. We still have places 660 // where it may be a block-level expression, so we need to 661 // generate an extra node that just propagates the value of the 662 // subexpression. 663 const Expr *Ex = U->getSubExpr()->IgnoreParens(); 664 ProgramStateRef state = Pred->getState(); 665 const LocationContext *LCtx = Pred->getLocationContext(); 666 Bldr.generateNode(U, Pred, state->BindExpr(U, LCtx, 667 state->getSVal(Ex, LCtx))); 668 break; 669 } 670 671 case UO_LNot: 672 case UO_Minus: 673 case UO_Not: { 674 assert (!U->isLValue()); 675 const Expr *Ex = U->getSubExpr()->IgnoreParens(); 676 ProgramStateRef state = Pred->getState(); 677 const LocationContext *LCtx = Pred->getLocationContext(); 678 679 // Get the value of the subexpression. 680 SVal V = state->getSVal(Ex, LCtx); 681 682 if (V.isUnknownOrUndef()) { 683 Bldr.generateNode(U, Pred, state->BindExpr(U, LCtx, V)); 684 break; 685 } 686 687 switch (U->getOpcode()) { 688 default: 689 llvm_unreachable("Invalid Opcode."); 690 case UO_Not: 691 // FIXME: Do we need to handle promotions? 692 state = state->BindExpr(U, LCtx, evalComplement(cast<NonLoc>(V))); 693 break; 694 case UO_Minus: 695 // FIXME: Do we need to handle promotions? 696 state = state->BindExpr(U, LCtx, evalMinus(cast<NonLoc>(V))); 697 break; 698 case UO_LNot: 699 // C99 6.5.3.3: "The expression !E is equivalent to (0==E)." 700 // 701 // Note: technically we do "E == 0", but this is the same in the 702 // transfer functions as "0 == E". 703 SVal Result; 704 if (isa<Loc>(V)) { 705 Loc X = svalBuilder.makeNull(); 706 Result = evalBinOp(state, BO_EQ, cast<Loc>(V), X, 707 U->getType()); 708 } 709 else { 710 nonloc::ConcreteInt X(getBasicVals().getValue(0, Ex->getType())); 711 Result = evalBinOp(state, BO_EQ, cast<NonLoc>(V), X, 712 U->getType()); 713 } 714 715 state = state->BindExpr(U, LCtx, Result); 716 break; 717 } 718 Bldr.generateNode(U, Pred, state); 719 break; 720 } 721 } 722 723 } 724 725 void ExprEngine::VisitIncrementDecrementOperator(const UnaryOperator* U, 726 ExplodedNode *Pred, 727 ExplodedNodeSet &Dst) { 728 // Handle ++ and -- (both pre- and post-increment). 729 assert (U->isIncrementDecrementOp()); 730 const Expr *Ex = U->getSubExpr()->IgnoreParens(); 731 732 const LocationContext *LCtx = Pred->getLocationContext(); 733 ProgramStateRef state = Pred->getState(); 734 SVal loc = state->getSVal(Ex, LCtx); 735 736 // Perform a load. 737 ExplodedNodeSet Tmp; 738 evalLoad(Tmp, U, Ex, Pred, state, loc); 739 740 ExplodedNodeSet Dst2; 741 StmtNodeBuilder Bldr(Tmp, Dst2, *currentBuilderContext); 742 for (ExplodedNodeSet::iterator I=Tmp.begin(), E=Tmp.end();I!=E;++I) { 743 744 state = (*I)->getState(); 745 assert(LCtx == (*I)->getLocationContext()); 746 SVal V2_untested = state->getSVal(Ex, LCtx); 747 748 // Propagate unknown and undefined values. 749 if (V2_untested.isUnknownOrUndef()) { 750 Bldr.generateNode(U, *I, state->BindExpr(U, LCtx, V2_untested)); 751 continue; 752 } 753 DefinedSVal V2 = cast<DefinedSVal>(V2_untested); 754 755 // Handle all other values. 756 BinaryOperator::Opcode Op = U->isIncrementOp() ? BO_Add : BO_Sub; 757 758 // If the UnaryOperator has non-location type, use its type to create the 759 // constant value. If the UnaryOperator has location type, create the 760 // constant with int type and pointer width. 761 SVal RHS; 762 763 if (U->getType()->isAnyPointerType()) 764 RHS = svalBuilder.makeArrayIndex(1); 765 else 766 RHS = svalBuilder.makeIntVal(1, U->getType()); 767 768 SVal Result = evalBinOp(state, Op, V2, RHS, U->getType()); 769 770 // Conjure a new symbol if necessary to recover precision. 771 if (Result.isUnknown()){ 772 DefinedOrUnknownSVal SymVal = 773 svalBuilder.getConjuredSymbolVal(NULL, Ex, LCtx, 774 currentBuilderContext->getCurrentBlockCount()); 775 Result = SymVal; 776 777 // If the value is a location, ++/-- should always preserve 778 // non-nullness. Check if the original value was non-null, and if so 779 // propagate that constraint. 780 if (Loc::isLocType(U->getType())) { 781 DefinedOrUnknownSVal Constraint = 782 svalBuilder.evalEQ(state, V2,svalBuilder.makeZeroVal(U->getType())); 783 784 if (!state->assume(Constraint, true)) { 785 // It isn't feasible for the original value to be null. 786 // Propagate this constraint. 787 Constraint = svalBuilder.evalEQ(state, SymVal, 788 svalBuilder.makeZeroVal(U->getType())); 789 790 791 state = state->assume(Constraint, false); 792 assert(state); 793 } 794 } 795 } 796 797 // Since the lvalue-to-rvalue conversion is explicit in the AST, 798 // we bind an l-value if the operator is prefix and an lvalue (in C++). 799 if (U->isLValue()) 800 state = state->BindExpr(U, LCtx, loc); 801 else 802 state = state->BindExpr(U, LCtx, U->isPostfix() ? V2 : Result); 803 804 // Perform the store. 805 Bldr.takeNodes(*I); 806 ExplodedNodeSet Dst3; 807 evalStore(Dst3, U, U, *I, state, loc, Result); 808 Bldr.addNodes(Dst3); 809 } 810 Dst.insert(Dst2); 811 } 812