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Diffstat (limited to 'clang/lib/StaticAnalyzer/Core/ExprEngineC.cpp')
| -rw-r--r-- | clang/lib/StaticAnalyzer/Core/ExprEngineC.cpp | 811 |
1 files changed, 811 insertions, 0 deletions
diff --git a/clang/lib/StaticAnalyzer/Core/ExprEngineC.cpp b/clang/lib/StaticAnalyzer/Core/ExprEngineC.cpp new file mode 100644 index 0000000..93e598a --- /dev/null +++ b/clang/lib/StaticAnalyzer/Core/ExprEngineC.cpp @@ -0,0 +1,811 @@ +//=-- ExprEngineC.cpp - ExprEngine support for C expressions ----*- C++ -*-===// +// +// The LLVM Compiler Infrastructure +// +// This file is distributed under the University of Illinois Open Source +// License. See LICENSE.TXT for details. +// +//===----------------------------------------------------------------------===// +// +// This file defines ExprEngine's support for C expressions. +// +//===----------------------------------------------------------------------===// + +#include "clang/StaticAnalyzer/Core/CheckerManager.h" +#include "clang/StaticAnalyzer/Core/PathSensitive/ExprEngine.h" + +using namespace clang; +using namespace ento; +using llvm::APSInt; + +void ExprEngine::VisitBinaryOperator(const BinaryOperator* B, + ExplodedNode *Pred, + ExplodedNodeSet &Dst) { + + Expr *LHS = B->getLHS()->IgnoreParens(); + Expr *RHS = B->getRHS()->IgnoreParens(); + + // FIXME: Prechecks eventually go in ::Visit(). + ExplodedNodeSet CheckedSet; + ExplodedNodeSet Tmp2; + getCheckerManager().runCheckersForPreStmt(CheckedSet, Pred, B, *this); + + // With both the LHS and RHS evaluated, process the operation itself. + for (ExplodedNodeSet::iterator it=CheckedSet.begin(), ei=CheckedSet.end(); + it != ei; ++it) { + + ProgramStateRef state = (*it)->getState(); + const LocationContext *LCtx = (*it)->getLocationContext(); + SVal LeftV = state->getSVal(LHS, LCtx); + SVal RightV = state->getSVal(RHS, LCtx); + + BinaryOperator::Opcode Op = B->getOpcode(); + + if (Op == BO_Assign) { + // EXPERIMENTAL: "Conjured" symbols. + // FIXME: Handle structs. + if (RightV.isUnknown()) { + unsigned Count = currentBuilderContext->getCurrentBlockCount(); + RightV = svalBuilder.getConjuredSymbolVal(NULL, B->getRHS(), LCtx, Count); + } + // Simulate the effects of a "store": bind the value of the RHS + // to the L-Value represented by the LHS. + SVal ExprVal = B->isLValue() ? LeftV : RightV; + evalStore(Tmp2, B, LHS, *it, state->BindExpr(B, LCtx, ExprVal), + LeftV, RightV); + continue; + } + + if (!B->isAssignmentOp()) { + StmtNodeBuilder Bldr(*it, Tmp2, *currentBuilderContext); + // Process non-assignments except commas or short-circuited + // logical expressions (LAnd and LOr). + SVal Result = evalBinOp(state, Op, LeftV, RightV, B->getType()); + if (Result.isUnknown()) { + Bldr.generateNode(B, *it, state); + continue; + } + + state = state->BindExpr(B, LCtx, Result); + Bldr.generateNode(B, *it, state); + continue; + } + + assert (B->isCompoundAssignmentOp()); + + switch (Op) { + default: + llvm_unreachable("Invalid opcode for compound assignment."); + case BO_MulAssign: Op = BO_Mul; break; + case BO_DivAssign: Op = BO_Div; break; + case BO_RemAssign: Op = BO_Rem; break; + case BO_AddAssign: Op = BO_Add; break; + case BO_SubAssign: Op = BO_Sub; break; + case BO_ShlAssign: Op = BO_Shl; break; + case BO_ShrAssign: Op = BO_Shr; break; + case BO_AndAssign: Op = BO_And; break; + case BO_XorAssign: Op = BO_Xor; break; + case BO_OrAssign: Op = BO_Or; break; + } + + // Perform a load (the LHS). This performs the checks for + // null dereferences, and so on. + ExplodedNodeSet Tmp; + SVal location = LeftV; + evalLoad(Tmp, B, LHS, *it, state, location); + + for (ExplodedNodeSet::iterator I = Tmp.begin(), E = Tmp.end(); I != E; + ++I) { + + state = (*I)->getState(); + const LocationContext *LCtx = (*I)->getLocationContext(); + SVal V = state->getSVal(LHS, LCtx); + + // Get the computation type. + QualType CTy = + cast<CompoundAssignOperator>(B)->getComputationResultType(); + CTy = getContext().getCanonicalType(CTy); + + QualType CLHSTy = + cast<CompoundAssignOperator>(B)->getComputationLHSType(); + CLHSTy = getContext().getCanonicalType(CLHSTy); + + QualType LTy = getContext().getCanonicalType(LHS->getType()); + + // Promote LHS. + V = svalBuilder.evalCast(V, CLHSTy, LTy); + + // Compute the result of the operation. + SVal Result = svalBuilder.evalCast(evalBinOp(state, Op, V, RightV, CTy), + B->getType(), CTy); + + // EXPERIMENTAL: "Conjured" symbols. + // FIXME: Handle structs. + + SVal LHSVal; + + if (Result.isUnknown()) { + + unsigned Count = currentBuilderContext->getCurrentBlockCount(); + + // The symbolic value is actually for the type of the left-hand side + // expression, not the computation type, as this is the value the + // LValue on the LHS will bind to. + LHSVal = svalBuilder.getConjuredSymbolVal(NULL, B->getRHS(), LCtx, + LTy, Count); + + // However, we need to convert the symbol to the computation type. + Result = svalBuilder.evalCast(LHSVal, CTy, LTy); + } + else { + // The left-hand side may bind to a different value then the + // computation type. + LHSVal = svalBuilder.evalCast(Result, LTy, CTy); + } + + // In C++, assignment and compound assignment operators return an + // lvalue. + if (B->isLValue()) + state = state->BindExpr(B, LCtx, location); + else + state = state->BindExpr(B, LCtx, Result); + + evalStore(Tmp2, B, LHS, *I, state, location, LHSVal); + } + } + + // FIXME: postvisits eventually go in ::Visit() + getCheckerManager().runCheckersForPostStmt(Dst, Tmp2, B, *this); +} + +void ExprEngine::VisitBlockExpr(const BlockExpr *BE, ExplodedNode *Pred, + ExplodedNodeSet &Dst) { + + CanQualType T = getContext().getCanonicalType(BE->getType()); + SVal V = svalBuilder.getBlockPointer(BE->getBlockDecl(), T, + Pred->getLocationContext()); + + ExplodedNodeSet Tmp; + StmtNodeBuilder Bldr(Pred, Tmp, *currentBuilderContext); + Bldr.generateNode(BE, Pred, + Pred->getState()->BindExpr(BE, Pred->getLocationContext(), + V), + false, 0, + ProgramPoint::PostLValueKind); + + // FIXME: Move all post/pre visits to ::Visit(). + getCheckerManager().runCheckersForPostStmt(Dst, Tmp, BE, *this); +} + +void ExprEngine::VisitCast(const CastExpr *CastE, const Expr *Ex, + ExplodedNode *Pred, ExplodedNodeSet &Dst) { + + ExplodedNodeSet dstPreStmt; + getCheckerManager().runCheckersForPreStmt(dstPreStmt, Pred, CastE, *this); + + if (CastE->getCastKind() == CK_LValueToRValue) { + for (ExplodedNodeSet::iterator I = dstPreStmt.begin(), E = dstPreStmt.end(); + I!=E; ++I) { + ExplodedNode *subExprNode = *I; + ProgramStateRef state = subExprNode->getState(); + const LocationContext *LCtx = subExprNode->getLocationContext(); + evalLoad(Dst, CastE, CastE, subExprNode, state, state->getSVal(Ex, LCtx)); + } + return; + } + + // All other casts. + QualType T = CastE->getType(); + QualType ExTy = Ex->getType(); + + if (const ExplicitCastExpr *ExCast=dyn_cast_or_null<ExplicitCastExpr>(CastE)) + T = ExCast->getTypeAsWritten(); + + StmtNodeBuilder Bldr(dstPreStmt, Dst, *currentBuilderContext); + for (ExplodedNodeSet::iterator I = dstPreStmt.begin(), E = dstPreStmt.end(); + I != E; ++I) { + + Pred = *I; + + switch (CastE->getCastKind()) { + case CK_LValueToRValue: + llvm_unreachable("LValueToRValue casts handled earlier."); + case CK_ToVoid: + continue; + // The analyzer doesn't do anything special with these casts, + // since it understands retain/release semantics already. + case CK_ARCProduceObject: + case CK_ARCConsumeObject: + case CK_ARCReclaimReturnedObject: + case CK_ARCExtendBlockObject: // Fall-through. + case CK_CopyAndAutoreleaseBlockObject: + // The analyser can ignore atomic casts for now, although some future + // checkers may want to make certain that you're not modifying the same + // value through atomic and nonatomic pointers. + case CK_AtomicToNonAtomic: + case CK_NonAtomicToAtomic: + // True no-ops. + case CK_NoOp: + case CK_FunctionToPointerDecay: { + // Copy the SVal of Ex to CastE. + ProgramStateRef state = Pred->getState(); + const LocationContext *LCtx = Pred->getLocationContext(); + SVal V = state->getSVal(Ex, LCtx); + state = state->BindExpr(CastE, LCtx, V); + Bldr.generateNode(CastE, Pred, state); + continue; + } + case CK_Dependent: + case CK_ArrayToPointerDecay: + case CK_BitCast: + case CK_LValueBitCast: + case CK_IntegralCast: + case CK_NullToPointer: + case CK_IntegralToPointer: + case CK_PointerToIntegral: + case CK_PointerToBoolean: + case CK_IntegralToBoolean: + case CK_IntegralToFloating: + case CK_FloatingToIntegral: + case CK_FloatingToBoolean: + case CK_FloatingCast: + case CK_FloatingRealToComplex: + case CK_FloatingComplexToReal: + case CK_FloatingComplexToBoolean: + case CK_FloatingComplexCast: + case CK_FloatingComplexToIntegralComplex: + case CK_IntegralRealToComplex: + case CK_IntegralComplexToReal: + case CK_IntegralComplexToBoolean: + case CK_IntegralComplexCast: + case CK_IntegralComplexToFloatingComplex: + case CK_CPointerToObjCPointerCast: + case CK_BlockPointerToObjCPointerCast: + case CK_AnyPointerToBlockPointerCast: + case CK_ObjCObjectLValueCast: { + // Delegate to SValBuilder to process. + ProgramStateRef state = Pred->getState(); + const LocationContext *LCtx = Pred->getLocationContext(); + SVal V = state->getSVal(Ex, LCtx); + V = svalBuilder.evalCast(V, T, ExTy); + state = state->BindExpr(CastE, LCtx, V); + Bldr.generateNode(CastE, Pred, state); + continue; + } + case CK_DerivedToBase: + case CK_UncheckedDerivedToBase: { + // For DerivedToBase cast, delegate to the store manager. + ProgramStateRef state = Pred->getState(); + const LocationContext *LCtx = Pred->getLocationContext(); + SVal val = state->getSVal(Ex, LCtx); + val = getStoreManager().evalDerivedToBase(val, T); + state = state->BindExpr(CastE, LCtx, val); + Bldr.generateNode(CastE, Pred, state); + continue; + } + // Handle C++ dyn_cast. + case CK_Dynamic: { + ProgramStateRef state = Pred->getState(); + const LocationContext *LCtx = Pred->getLocationContext(); + SVal val = state->getSVal(Ex, LCtx); + + // Compute the type of the result. + QualType resultType = CastE->getType(); + if (CastE->isLValue()) + resultType = getContext().getPointerType(resultType); + + bool Failed = false; + + // Check if the value being cast evaluates to 0. + if (val.isZeroConstant()) + Failed = true; + // Else, evaluate the cast. + else + val = getStoreManager().evalDynamicCast(val, T, Failed); + + if (Failed) { + if (T->isReferenceType()) { + // A bad_cast exception is thrown if input value is a reference. + // Currently, we model this, by generating a sink. + Bldr.generateNode(CastE, Pred, state, true); + continue; + } else { + // If the cast fails on a pointer, bind to 0. + state = state->BindExpr(CastE, LCtx, svalBuilder.makeNull()); + } + } else { + // If we don't know if the cast succeeded, conjure a new symbol. + if (val.isUnknown()) { + DefinedOrUnknownSVal NewSym = svalBuilder.getConjuredSymbolVal(NULL, + CastE, LCtx, resultType, + currentBuilderContext->getCurrentBlockCount()); + state = state->BindExpr(CastE, LCtx, NewSym); + } else + // Else, bind to the derived region value. + state = state->BindExpr(CastE, LCtx, val); + } + Bldr.generateNode(CastE, Pred, state); + continue; + } + // Various C++ casts that are not handled yet. + case CK_ToUnion: + case CK_BaseToDerived: + case CK_NullToMemberPointer: + case CK_BaseToDerivedMemberPointer: + case CK_DerivedToBaseMemberPointer: + case CK_ReinterpretMemberPointer: + case CK_UserDefinedConversion: + case CK_ConstructorConversion: + case CK_VectorSplat: + case CK_MemberPointerToBoolean: { + // Recover some path-sensitivty by conjuring a new value. + QualType resultType = CastE->getType(); + if (CastE->isLValue()) + resultType = getContext().getPointerType(resultType); + const LocationContext *LCtx = Pred->getLocationContext(); + SVal result = svalBuilder.getConjuredSymbolVal(NULL, CastE, LCtx, + resultType, currentBuilderContext->getCurrentBlockCount()); + ProgramStateRef state = Pred->getState()->BindExpr(CastE, LCtx, + result); + Bldr.generateNode(CastE, Pred, state); + continue; + } + } + } +} + +void ExprEngine::VisitCompoundLiteralExpr(const CompoundLiteralExpr *CL, + ExplodedNode *Pred, + ExplodedNodeSet &Dst) { + StmtNodeBuilder B(Pred, Dst, *currentBuilderContext); + + const InitListExpr *ILE + = cast<InitListExpr>(CL->getInitializer()->IgnoreParens()); + + ProgramStateRef state = Pred->getState(); + SVal ILV = state->getSVal(ILE, Pred->getLocationContext()); + const LocationContext *LC = Pred->getLocationContext(); + state = state->bindCompoundLiteral(CL, LC, ILV); + + if (CL->isLValue()) + B.generateNode(CL, Pred, state->BindExpr(CL, LC, state->getLValue(CL, LC))); + else + B.generateNode(CL, Pred, state->BindExpr(CL, LC, ILV)); +} + +void ExprEngine::VisitDeclStmt(const DeclStmt *DS, ExplodedNode *Pred, + ExplodedNodeSet &Dst) { + + // FIXME: static variables may have an initializer, but the second + // time a function is called those values may not be current. + // This may need to be reflected in the CFG. + + // Assumption: The CFG has one DeclStmt per Decl. + const Decl *D = *DS->decl_begin(); + + if (!D || !isa<VarDecl>(D)) { + //TODO:AZ: remove explicit insertion after refactoring is done. + Dst.insert(Pred); + return; + } + + // FIXME: all pre/post visits should eventually be handled by ::Visit(). + ExplodedNodeSet dstPreVisit; + getCheckerManager().runCheckersForPreStmt(dstPreVisit, Pred, DS, *this); + + StmtNodeBuilder B(dstPreVisit, Dst, *currentBuilderContext); + const VarDecl *VD = dyn_cast<VarDecl>(D); + for (ExplodedNodeSet::iterator I = dstPreVisit.begin(), E = dstPreVisit.end(); + I!=E; ++I) { + ExplodedNode *N = *I; + ProgramStateRef state = N->getState(); + + // Decls without InitExpr are not initialized explicitly. + const LocationContext *LC = N->getLocationContext(); + + if (const Expr *InitEx = VD->getInit()) { + SVal InitVal = state->getSVal(InitEx, Pred->getLocationContext()); + + // We bound the temp obj region to the CXXConstructExpr. Now recover + // the lazy compound value when the variable is not a reference. + if (AMgr.getLangOpts().CPlusPlus && VD->getType()->isRecordType() && + !VD->getType()->isReferenceType() && isa<loc::MemRegionVal>(InitVal)){ + InitVal = state->getSVal(cast<loc::MemRegionVal>(InitVal).getRegion()); + assert(isa<nonloc::LazyCompoundVal>(InitVal)); + } + + // Recover some path-sensitivity if a scalar value evaluated to + // UnknownVal. + if (InitVal.isUnknown()) { + QualType Ty = InitEx->getType(); + if (InitEx->isLValue()) { + Ty = getContext().getPointerType(Ty); + } + + InitVal = svalBuilder.getConjuredSymbolVal(NULL, InitEx, LC, Ty, + currentBuilderContext->getCurrentBlockCount()); + } + B.takeNodes(N); + ExplodedNodeSet Dst2; + evalBind(Dst2, DS, N, state->getLValue(VD, LC), InitVal, true); + B.addNodes(Dst2); + } + else { + B.generateNode(DS, N,state->bindDeclWithNoInit(state->getRegion(VD, LC))); + } + } +} + +void ExprEngine::VisitLogicalExpr(const BinaryOperator* B, ExplodedNode *Pred, + ExplodedNodeSet &Dst) { + assert(B->getOpcode() == BO_LAnd || + B->getOpcode() == BO_LOr); + + StmtNodeBuilder Bldr(Pred, Dst, *currentBuilderContext); + ProgramStateRef state = Pred->getState(); + const LocationContext *LCtx = Pred->getLocationContext(); + SVal X = state->getSVal(B, LCtx); + assert(X.isUndef()); + + const Expr *Ex = (const Expr*) cast<UndefinedVal>(X).getData(); + assert(Ex); + + if (Ex == B->getRHS()) { + X = state->getSVal(Ex, LCtx); + + // Handle undefined values. + if (X.isUndef()) { + Bldr.generateNode(B, Pred, state->BindExpr(B, LCtx, X)); + return; + } + + DefinedOrUnknownSVal XD = cast<DefinedOrUnknownSVal>(X); + + // We took the RHS. Because the value of the '&&' or '||' expression must + // evaluate to 0 or 1, we must assume the value of the RHS evaluates to 0 + // or 1. Alternatively, we could take a lazy approach, and calculate this + // value later when necessary. We don't have the machinery in place for + // this right now, and since most logical expressions are used for branches, + // the payoff is not likely to be large. Instead, we do eager evaluation. + if (ProgramStateRef newState = state->assume(XD, true)) + Bldr.generateNode(B, Pred, + newState->BindExpr(B, LCtx, + svalBuilder.makeIntVal(1U, B->getType()))); + + if (ProgramStateRef newState = state->assume(XD, false)) + Bldr.generateNode(B, Pred, + newState->BindExpr(B, LCtx, + svalBuilder.makeIntVal(0U, B->getType()))); + } + else { + // We took the LHS expression. Depending on whether we are '&&' or + // '||' we know what the value of the expression is via properties of + // the short-circuiting. + X = svalBuilder.makeIntVal(B->getOpcode() == BO_LAnd ? 0U : 1U, + B->getType()); + Bldr.generateNode(B, Pred, state->BindExpr(B, LCtx, X)); + } +} + +void ExprEngine::VisitInitListExpr(const InitListExpr *IE, + ExplodedNode *Pred, + ExplodedNodeSet &Dst) { + StmtNodeBuilder B(Pred, Dst, *currentBuilderContext); + + ProgramStateRef state = Pred->getState(); + const LocationContext *LCtx = Pred->getLocationContext(); + QualType T = getContext().getCanonicalType(IE->getType()); + unsigned NumInitElements = IE->getNumInits(); + + if (T->isArrayType() || T->isRecordType() || T->isVectorType()) { + llvm::ImmutableList<SVal> vals = getBasicVals().getEmptySValList(); + + // Handle base case where the initializer has no elements. + // e.g: static int* myArray[] = {}; + if (NumInitElements == 0) { + SVal V = svalBuilder.makeCompoundVal(T, vals); + B.generateNode(IE, Pred, state->BindExpr(IE, LCtx, V)); + return; + } + + for (InitListExpr::const_reverse_iterator it = IE->rbegin(), + ei = IE->rend(); it != ei; ++it) { + vals = getBasicVals().consVals(state->getSVal(cast<Expr>(*it), LCtx), + vals); + } + + B.generateNode(IE, Pred, + state->BindExpr(IE, LCtx, + svalBuilder.makeCompoundVal(T, vals))); + return; + } + + if (Loc::isLocType(T) || T->isIntegerType()) { + assert(IE->getNumInits() == 1); + const Expr *initEx = IE->getInit(0); + B.generateNode(IE, Pred, state->BindExpr(IE, LCtx, + state->getSVal(initEx, LCtx))); + return; + } + + llvm_unreachable("unprocessed InitListExpr type"); +} + +void ExprEngine::VisitGuardedExpr(const Expr *Ex, + const Expr *L, + const Expr *R, + ExplodedNode *Pred, + ExplodedNodeSet &Dst) { + StmtNodeBuilder B(Pred, Dst, *currentBuilderContext); + + ProgramStateRef state = Pred->getState(); + const LocationContext *LCtx = Pred->getLocationContext(); + SVal X = state->getSVal(Ex, LCtx); + assert (X.isUndef()); + const Expr *SE = (Expr*) cast<UndefinedVal>(X).getData(); + assert(SE); + X = state->getSVal(SE, LCtx); + + // Make sure that we invalidate the previous binding. + B.generateNode(Ex, Pred, state->BindExpr(Ex, LCtx, X, true)); +} + +void ExprEngine:: +VisitOffsetOfExpr(const OffsetOfExpr *OOE, + ExplodedNode *Pred, ExplodedNodeSet &Dst) { + StmtNodeBuilder B(Pred, Dst, *currentBuilderContext); + APSInt IV; + if (OOE->EvaluateAsInt(IV, getContext())) { + assert(IV.getBitWidth() == getContext().getTypeSize(OOE->getType())); + assert(OOE->getType()->isIntegerType()); + assert(IV.isSigned() == OOE->getType()->isSignedIntegerOrEnumerationType()); + SVal X = svalBuilder.makeIntVal(IV); + B.generateNode(OOE, Pred, + Pred->getState()->BindExpr(OOE, Pred->getLocationContext(), + X)); + } + // FIXME: Handle the case where __builtin_offsetof is not a constant. +} + + +void ExprEngine:: +VisitUnaryExprOrTypeTraitExpr(const UnaryExprOrTypeTraitExpr *Ex, + ExplodedNode *Pred, + ExplodedNodeSet &Dst) { + StmtNodeBuilder Bldr(Pred, Dst, *currentBuilderContext); + + QualType T = Ex->getTypeOfArgument(); + + if (Ex->getKind() == UETT_SizeOf) { + if (!T->isIncompleteType() && !T->isConstantSizeType()) { + assert(T->isVariableArrayType() && "Unknown non-constant-sized type."); + + // FIXME: Add support for VLA type arguments and VLA expressions. + // When that happens, we should probably refactor VLASizeChecker's code. + return; + } + else if (T->getAs<ObjCObjectType>()) { + // Some code tries to take the sizeof an ObjCObjectType, relying that + // the compiler has laid out its representation. Just report Unknown + // for these. + return; + } + } + + APSInt Value = Ex->EvaluateKnownConstInt(getContext()); + CharUnits amt = CharUnits::fromQuantity(Value.getZExtValue()); + + ProgramStateRef state = Pred->getState(); + state = state->BindExpr(Ex, Pred->getLocationContext(), + svalBuilder.makeIntVal(amt.getQuantity(), + Ex->getType())); + Bldr.generateNode(Ex, Pred, state); +} + +void ExprEngine::VisitUnaryOperator(const UnaryOperator* U, + ExplodedNode *Pred, + ExplodedNodeSet &Dst) { + StmtNodeBuilder Bldr(Pred, Dst, *currentBuilderContext); + switch (U->getOpcode()) { + default: { + Bldr.takeNodes(Pred); + ExplodedNodeSet Tmp; + VisitIncrementDecrementOperator(U, Pred, Tmp); + Bldr.addNodes(Tmp); + } + break; + case UO_Real: { + const Expr *Ex = U->getSubExpr()->IgnoreParens(); + + // FIXME: We don't have complex SValues yet. + if (Ex->getType()->isAnyComplexType()) { + // Just report "Unknown." + break; + } + + // For all other types, UO_Real is an identity operation. + assert (U->getType() == Ex->getType()); + ProgramStateRef state = Pred->getState(); + const LocationContext *LCtx = Pred->getLocationContext(); + Bldr.generateNode(U, Pred, state->BindExpr(U, LCtx, + state->getSVal(Ex, LCtx))); + break; + } + + case UO_Imag: { + const Expr *Ex = U->getSubExpr()->IgnoreParens(); + // FIXME: We don't have complex SValues yet. + if (Ex->getType()->isAnyComplexType()) { + // Just report "Unknown." + break; + } + // For all other types, UO_Imag returns 0. + ProgramStateRef state = Pred->getState(); + const LocationContext *LCtx = Pred->getLocationContext(); + SVal X = svalBuilder.makeZeroVal(Ex->getType()); + Bldr.generateNode(U, Pred, state->BindExpr(U, LCtx, X)); + break; + } + + case UO_Plus: + assert(!U->isLValue()); + // FALL-THROUGH. + case UO_Deref: + case UO_AddrOf: + case UO_Extension: { + // FIXME: We can probably just have some magic in Environment::getSVal() + // that propagates values, instead of creating a new node here. + // + // Unary "+" is a no-op, similar to a parentheses. We still have places + // where it may be a block-level expression, so we need to + // generate an extra node that just propagates the value of the + // subexpression. + const Expr *Ex = U->getSubExpr()->IgnoreParens(); + ProgramStateRef state = Pred->getState(); + const LocationContext *LCtx = Pred->getLocationContext(); + Bldr.generateNode(U, Pred, state->BindExpr(U, LCtx, + state->getSVal(Ex, LCtx))); + break; + } + + case UO_LNot: + case UO_Minus: + case UO_Not: { + assert (!U->isLValue()); + const Expr *Ex = U->getSubExpr()->IgnoreParens(); + ProgramStateRef state = Pred->getState(); + const LocationContext *LCtx = Pred->getLocationContext(); + + // Get the value of the subexpression. + SVal V = state->getSVal(Ex, LCtx); + + if (V.isUnknownOrUndef()) { + Bldr.generateNode(U, Pred, state->BindExpr(U, LCtx, V)); + break; + } + + switch (U->getOpcode()) { + default: + llvm_unreachable("Invalid Opcode."); + case UO_Not: + // FIXME: Do we need to handle promotions? + state = state->BindExpr(U, LCtx, evalComplement(cast<NonLoc>(V))); + break; + case UO_Minus: + // FIXME: Do we need to handle promotions? + state = state->BindExpr(U, LCtx, evalMinus(cast<NonLoc>(V))); + break; + case UO_LNot: + // C99 6.5.3.3: "The expression !E is equivalent to (0==E)." + // + // Note: technically we do "E == 0", but this is the same in the + // transfer functions as "0 == E". + SVal Result; + if (isa<Loc>(V)) { + Loc X = svalBuilder.makeNull(); + Result = evalBinOp(state, BO_EQ, cast<Loc>(V), X, + U->getType()); + } + else { + nonloc::ConcreteInt X(getBasicVals().getValue(0, Ex->getType())); + Result = evalBinOp(state, BO_EQ, cast<NonLoc>(V), X, + U->getType()); + } + + state = state->BindExpr(U, LCtx, Result); + break; + } + Bldr.generateNode(U, Pred, state); + break; + } + } + +} + +void ExprEngine::VisitIncrementDecrementOperator(const UnaryOperator* U, + ExplodedNode *Pred, + ExplodedNodeSet &Dst) { + // Handle ++ and -- (both pre- and post-increment). + assert (U->isIncrementDecrementOp()); + const Expr *Ex = U->getSubExpr()->IgnoreParens(); + + const LocationContext *LCtx = Pred->getLocationContext(); + ProgramStateRef state = Pred->getState(); + SVal loc = state->getSVal(Ex, LCtx); + + // Perform a load. + ExplodedNodeSet Tmp; + evalLoad(Tmp, U, Ex, Pred, state, loc); + + ExplodedNodeSet Dst2; + StmtNodeBuilder Bldr(Tmp, Dst2, *currentBuilderContext); + for (ExplodedNodeSet::iterator I=Tmp.begin(), E=Tmp.end();I!=E;++I) { + + state = (*I)->getState(); + assert(LCtx == (*I)->getLocationContext()); + SVal V2_untested = state->getSVal(Ex, LCtx); + + // Propagate unknown and undefined values. + if (V2_untested.isUnknownOrUndef()) { + Bldr.generateNode(U, *I, state->BindExpr(U, LCtx, V2_untested)); + continue; + } + DefinedSVal V2 = cast<DefinedSVal>(V2_untested); + + // Handle all other values. + BinaryOperator::Opcode Op = U->isIncrementOp() ? BO_Add : BO_Sub; + + // If the UnaryOperator has non-location type, use its type to create the + // constant value. If the UnaryOperator has location type, create the + // constant with int type and pointer width. + SVal RHS; + + if (U->getType()->isAnyPointerType()) + RHS = svalBuilder.makeArrayIndex(1); + else + RHS = svalBuilder.makeIntVal(1, U->getType()); + + SVal Result = evalBinOp(state, Op, V2, RHS, U->getType()); + + // Conjure a new symbol if necessary to recover precision. + if (Result.isUnknown()){ + DefinedOrUnknownSVal SymVal = + svalBuilder.getConjuredSymbolVal(NULL, Ex, LCtx, + currentBuilderContext->getCurrentBlockCount()); + Result = SymVal; + + // If the value is a location, ++/-- should always preserve + // non-nullness. Check if the original value was non-null, and if so + // propagate that constraint. + if (Loc::isLocType(U->getType())) { + DefinedOrUnknownSVal Constraint = + svalBuilder.evalEQ(state, V2,svalBuilder.makeZeroVal(U->getType())); + + if (!state->assume(Constraint, true)) { + // It isn't feasible for the original value to be null. + // Propagate this constraint. + Constraint = svalBuilder.evalEQ(state, SymVal, + svalBuilder.makeZeroVal(U->getType())); + + + state = state->assume(Constraint, false); + assert(state); + } + } + } + + // Since the lvalue-to-rvalue conversion is explicit in the AST, + // we bind an l-value if the operator is prefix and an lvalue (in C++). + if (U->isLValue()) + state = state->BindExpr(U, LCtx, loc); + else + state = state->BindExpr(U, LCtx, U->isPostfix() ? V2 : Result); + + // Perform the store. + Bldr.takeNodes(*I); + ExplodedNodeSet Dst3; + evalStore(Dst3, U, U, *I, state, loc, Result); + Bldr.addNodes(Dst3); + } + Dst.insert(Dst2); +} |