| //=-- 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/AST/ExprCXX.h" |
| #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 = currBldrCtx->blockCount(); |
| RightV = svalBuilder.conjureSymbolVal(0, 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->isGLValue() ? LeftV : RightV; |
| evalStore(Tmp2, B, LHS, *it, state->BindExpr(B, LCtx, ExprVal), |
| LeftV, RightV); |
| continue; |
| } |
| |
| if (!B->isAssignmentOp()) { |
| StmtNodeBuilder Bldr(*it, Tmp2, *currBldrCtx); |
| |
| if (B->isAdditiveOp()) { |
| // If one of the operands is a location, conjure a symbol for the other |
| // one (offset) if it's unknown so that memory arithmetic always |
| // results in an ElementRegion. |
| // TODO: This can be removed after we enable history tracking with |
| // SymSymExpr. |
| unsigned Count = currBldrCtx->blockCount(); |
| if (LeftV.getAs<Loc>() && |
| RHS->getType()->isIntegerType() && RightV.isUnknown()) { |
| RightV = svalBuilder.conjureSymbolVal(RHS, LCtx, RHS->getType(), |
| Count); |
| } |
| if (RightV.getAs<Loc>() && |
| LHS->getType()->isIntegerType() && LeftV.isUnknown()) { |
| LeftV = svalBuilder.conjureSymbolVal(LHS, LCtx, LHS->getType(), |
| Count); |
| } |
| } |
| |
| // 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()) { |
| // 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.conjureSymbolVal(0, B->getRHS(), LCtx, LTy, |
| currBldrCtx->blockCount()); |
| // 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->isGLValue()) |
| 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()); |
| |
| // Get the value of the block itself. |
| SVal V = svalBuilder.getBlockPointer(BE->getBlockDecl(), T, |
| Pred->getLocationContext()); |
| |
| ProgramStateRef State = Pred->getState(); |
| |
| // If we created a new MemRegion for the block, we should explicitly bind |
| // the captured variables. |
| if (const BlockDataRegion *BDR = |
| dyn_cast_or_null<BlockDataRegion>(V.getAsRegion())) { |
| |
| BlockDataRegion::referenced_vars_iterator I = BDR->referenced_vars_begin(), |
| E = BDR->referenced_vars_end(); |
| |
| for (; I != E; ++I) { |
| const MemRegion *capturedR = I.getCapturedRegion(); |
| const MemRegion *originalR = I.getOriginalRegion(); |
| if (capturedR != originalR) { |
| SVal originalV = State->getSVal(loc::MemRegionVal(originalR)); |
| State = State->bindLoc(loc::MemRegionVal(capturedR), originalV); |
| } |
| } |
| } |
| |
| ExplodedNodeSet Tmp; |
| StmtNodeBuilder Bldr(Pred, Tmp, *currBldrCtx); |
| Bldr.generateNode(BE, Pred, |
| State->BindExpr(BE, Pred->getLocationContext(), V), |
| 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, *currBldrCtx); |
| for (ExplodedNodeSet::iterator I = dstPreStmt.begin(), E = dstPreStmt.end(); |
| I != E; ++I) { |
| |
| Pred = *I; |
| ProgramStateRef state = Pred->getState(); |
| const LocationContext *LCtx = Pred->getLocationContext(); |
| |
| 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_ConstructorConversion: |
| case CK_UserDefinedConversion: |
| case CK_FunctionToPointerDecay: |
| case CK_BuiltinFnToFnPtr: { |
| // 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_MemberPointerToBoolean: |
| // FIXME: For now, member pointers are represented by void *. |
| // FALLTHROUGH |
| case CK_Dependent: |
| case CK_ArrayToPointerDecay: |
| case CK_BitCast: |
| 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: |
| case CK_ZeroToOCLEvent: { |
| // Delegate to SValBuilder to process. |
| 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. |
| SVal val = state->getSVal(Ex, LCtx); |
| val = getStoreManager().evalDerivedToBase(val, CastE); |
| state = state->BindExpr(CastE, LCtx, val); |
| Bldr.generateNode(CastE, Pred, state); |
| continue; |
| } |
| // Handle C++ dyn_cast. |
| case CK_Dynamic: { |
| SVal val = state->getSVal(Ex, LCtx); |
| |
| // Compute the type of the result. |
| QualType resultType = CastE->getType(); |
| if (CastE->isGLValue()) |
| 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.generateSink(CastE, Pred, state); |
| 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.conjureSymbolVal(0, CastE, LCtx, resultType, |
| currBldrCtx->blockCount()); |
| 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; |
| } |
| case CK_NullToMemberPointer: { |
| // FIXME: For now, member pointers are represented by void *. |
| SVal V = svalBuilder.makeIntValWithPtrWidth(0, true); |
| state = state->BindExpr(CastE, LCtx, V); |
| Bldr.generateNode(CastE, Pred, state); |
| continue; |
| } |
| // Various C++ casts that are not handled yet. |
| case CK_ToUnion: |
| case CK_BaseToDerived: |
| case CK_BaseToDerivedMemberPointer: |
| case CK_DerivedToBaseMemberPointer: |
| case CK_ReinterpretMemberPointer: |
| case CK_VectorSplat: |
| case CK_LValueBitCast: { |
| // Recover some path-sensitivty by conjuring a new value. |
| QualType resultType = CastE->getType(); |
| if (CastE->isGLValue()) |
| resultType = getContext().getPointerType(resultType); |
| SVal result = svalBuilder.conjureSymbolVal(0, CastE, LCtx, |
| resultType, |
| currBldrCtx->blockCount()); |
| state = state->BindExpr(CastE, LCtx, result); |
| Bldr.generateNode(CastE, Pred, state); |
| continue; |
| } |
| } |
| } |
| } |
| |
| void ExprEngine::VisitCompoundLiteralExpr(const CompoundLiteralExpr *CL, |
| ExplodedNode *Pred, |
| ExplodedNodeSet &Dst) { |
| StmtNodeBuilder B(Pred, Dst, *currBldrCtx); |
| |
| 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); |
| |
| // Compound literal expressions are a GNU extension in C++. |
| // Unlike in C, where CLs are lvalues, in C++ CLs are prvalues, |
| // and like temporary objects created by the functional notation T() |
| // CLs are destroyed at the end of the containing full-expression. |
| // HOWEVER, an rvalue of array type is not something the analyzer can |
| // reason about, since we expect all regions to be wrapped in Locs. |
| // So we treat array CLs as lvalues as well, knowing that they will decay |
| // to pointers as soon as they are used. |
| if (CL->isGLValue() || CL->getType()->isArrayType()) |
| B.generateNode(CL, Pred, state->BindExpr(CL, LC, state->getLValue(CL, LC))); |
| else |
| B.generateNode(CL, Pred, state->BindExpr(CL, LC, ILV)); |
| } |
| |
| /// The GDM component containing the set of global variables which have been |
| /// previously initialized with explicit initializers. |
| REGISTER_TRAIT_WITH_PROGRAMSTATE(InitializedGlobalsSet, |
| llvm::ImmutableSet<const VarDecl *> ) |
| |
| void ExprEngine::VisitDeclStmt(const DeclStmt *DS, ExplodedNode *Pred, |
| ExplodedNodeSet &Dst) { |
| // Assumption: The CFG has one DeclStmt per Decl. |
| const VarDecl *VD = dyn_cast_or_null<VarDecl>(*DS->decl_begin()); |
| |
| if (!VD) { |
| //TODO:AZ: remove explicit insertion after refactoring is done. |
| Dst.insert(Pred); |
| return; |
| } |
| |
| // Check if a value has been previously initialized. There will be an entry in |
| // the set for variables with global storage which have been previously |
| // initialized. |
| if (VD->hasGlobalStorage()) |
| if (Pred->getState()->contains<InitializedGlobalsSet>(VD)) { |
| 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, *currBldrCtx); |
| for (ExplodedNodeSet::iterator I = dstPreVisit.begin(), E = dstPreVisit.end(); |
| I!=E; ++I) { |
| ExplodedNode *N = *I; |
| ProgramStateRef state = N->getState(); |
| const LocationContext *LC = N->getLocationContext(); |
| |
| // Decls without InitExpr are not initialized explicitly. |
| if (const Expr *InitEx = VD->getInit()) { |
| |
| // Note in the state that the initialization has occurred. |
| ExplodedNode *UpdatedN = N; |
| if (VD->hasGlobalStorage()) { |
| state = state->add<InitializedGlobalsSet>(VD); |
| UpdatedN = B.generateNode(DS, N, state); |
| } |
| |
| SVal InitVal = state->getSVal(InitEx, LC); |
| |
| if (isa<CXXConstructExpr>(InitEx->IgnoreImplicit())) { |
| // We constructed the object directly in the variable. |
| // No need to bind anything. |
| B.generateNode(DS, UpdatedN, state); |
| } else { |
| // 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()) { |
| if (Optional<loc::MemRegionVal> M = |
| InitVal.getAs<loc::MemRegionVal>()) { |
| InitVal = state->getSVal(M->getRegion()); |
| assert(InitVal.getAs<nonloc::LazyCompoundVal>()); |
| } |
| } |
| |
| // Recover some path-sensitivity if a scalar value evaluated to |
| // UnknownVal. |
| if (InitVal.isUnknown()) { |
| QualType Ty = InitEx->getType(); |
| if (InitEx->isGLValue()) { |
| Ty = getContext().getPointerType(Ty); |
| } |
| |
| InitVal = svalBuilder.conjureSymbolVal(0, InitEx, LC, Ty, |
| currBldrCtx->blockCount()); |
| } |
| |
| |
| B.takeNodes(UpdatedN); |
| ExplodedNodeSet Dst2; |
| evalBind(Dst2, DS, UpdatedN, state->getLValue(VD, LC), InitVal, true); |
| B.addNodes(Dst2); |
| } |
| } |
| else { |
| B.generateNode(DS, N, state); |
| } |
| } |
| } |
| |
| void ExprEngine::VisitLogicalExpr(const BinaryOperator* B, ExplodedNode *Pred, |
| ExplodedNodeSet &Dst) { |
| assert(B->getOpcode() == BO_LAnd || |
| B->getOpcode() == BO_LOr); |
| |
| StmtNodeBuilder Bldr(Pred, Dst, *currBldrCtx); |
| ProgramStateRef state = Pred->getState(); |
| |
| ExplodedNode *N = Pred; |
| while (!N->getLocation().getAs<BlockEntrance>()) { |
| ProgramPoint P = N->getLocation(); |
| assert(P.getAs<PreStmt>()|| P.getAs<PreStmtPurgeDeadSymbols>()); |
| (void) P; |
| assert(N->pred_size() == 1); |
| N = *N->pred_begin(); |
| } |
| assert(N->pred_size() == 1); |
| N = *N->pred_begin(); |
| BlockEdge BE = N->getLocation().castAs<BlockEdge>(); |
| SVal X; |
| |
| // Determine the value of the expression by introspecting how we |
| // got this location in the CFG. This requires looking at the previous |
| // block we were in and what kind of control-flow transfer was involved. |
| const CFGBlock *SrcBlock = BE.getSrc(); |
| // The only terminator (if there is one) that makes sense is a logical op. |
| CFGTerminator T = SrcBlock->getTerminator(); |
| if (const BinaryOperator *Term = cast_or_null<BinaryOperator>(T.getStmt())) { |
| (void) Term; |
| assert(Term->isLogicalOp()); |
| assert(SrcBlock->succ_size() == 2); |
| // Did we take the true or false branch? |
| unsigned constant = (*SrcBlock->succ_begin() == BE.getDst()) ? 1 : 0; |
| X = svalBuilder.makeIntVal(constant, B->getType()); |
| } |
| else { |
| // If there is no terminator, by construction the last statement |
| // in SrcBlock is the value of the enclosing expression. |
| // However, we still need to constrain that value to be 0 or 1. |
| assert(!SrcBlock->empty()); |
| CFGStmt Elem = SrcBlock->rbegin()->castAs<CFGStmt>(); |
| const Expr *RHS = cast<Expr>(Elem.getStmt()); |
| SVal RHSVal = N->getState()->getSVal(RHS, Pred->getLocationContext()); |
| |
| if (RHSVal.isUndef()) { |
| X = RHSVal; |
| } else { |
| DefinedOrUnknownSVal DefinedRHS = RHSVal.castAs<DefinedOrUnknownSVal>(); |
| ProgramStateRef StTrue, StFalse; |
| llvm::tie(StTrue, StFalse) = N->getState()->assume(DefinedRHS); |
| if (StTrue) { |
| if (StFalse) { |
| // We can't constrain the value to 0 or 1. |
| // The best we can do is a cast. |
| X = getSValBuilder().evalCast(RHSVal, B->getType(), RHS->getType()); |
| } else { |
| // The value is known to be true. |
| X = getSValBuilder().makeIntVal(1, B->getType()); |
| } |
| } else { |
| // The value is known to be false. |
| assert(StFalse && "Infeasible path!"); |
| X = getSValBuilder().makeIntVal(0, B->getType()); |
| } |
| } |
| } |
| Bldr.generateNode(B, Pred, state->BindExpr(B, Pred->getLocationContext(), X)); |
| } |
| |
| void ExprEngine::VisitInitListExpr(const InitListExpr *IE, |
| ExplodedNode *Pred, |
| ExplodedNodeSet &Dst) { |
| StmtNodeBuilder B(Pred, Dst, *currBldrCtx); |
| |
| 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() || |
| T->isAnyComplexType()) { |
| 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) { |
| SVal V = state->getSVal(cast<Expr>(*it), LCtx); |
| if (dyn_cast_or_null<CXXTempObjectRegion>(V.getAsRegion())) |
| V = UnknownVal(); |
| vals = getBasicVals().consVals(V, vals); |
| } |
| |
| B.generateNode(IE, Pred, |
| state->BindExpr(IE, LCtx, |
| svalBuilder.makeCompoundVal(T, vals))); |
| return; |
| } |
| |
| // Handle scalars: int{5} and int{}. |
| assert(NumInitElements <= 1); |
| |
| SVal V; |
| if (NumInitElements == 0) |
| V = getSValBuilder().makeZeroVal(T); |
| else |
| V = state->getSVal(IE->getInit(0), LCtx); |
| |
| B.generateNode(IE, Pred, state->BindExpr(IE, LCtx, V)); |
| } |
| |
| void ExprEngine::VisitGuardedExpr(const Expr *Ex, |
| const Expr *L, |
| const Expr *R, |
| ExplodedNode *Pred, |
| ExplodedNodeSet &Dst) { |
| StmtNodeBuilder B(Pred, Dst, *currBldrCtx); |
| ProgramStateRef state = Pred->getState(); |
| const LocationContext *LCtx = Pred->getLocationContext(); |
| const CFGBlock *SrcBlock = 0; |
| |
| for (const ExplodedNode *N = Pred ; N ; N = *N->pred_begin()) { |
| ProgramPoint PP = N->getLocation(); |
| if (PP.getAs<PreStmtPurgeDeadSymbols>() || PP.getAs<BlockEntrance>()) { |
| assert(N->pred_size() == 1); |
| continue; |
| } |
| SrcBlock = PP.castAs<BlockEdge>().getSrc(); |
| break; |
| } |
| |
| assert(SrcBlock && "missing function entry"); |
| |
| // Find the last expression in the predecessor block. That is the |
| // expression that is used for the value of the ternary expression. |
| bool hasValue = false; |
| SVal V; |
| |
| for (CFGBlock::const_reverse_iterator I = SrcBlock->rbegin(), |
| E = SrcBlock->rend(); I != E; ++I) { |
| CFGElement CE = *I; |
| if (Optional<CFGStmt> CS = CE.getAs<CFGStmt>()) { |
| const Expr *ValEx = cast<Expr>(CS->getStmt()); |
| hasValue = true; |
| V = state->getSVal(ValEx, LCtx); |
| break; |
| } |
| } |
| |
| assert(hasValue); |
| (void) hasValue; |
| |
| // Generate a new node with the binding from the appropriate path. |
| B.generateNode(Ex, Pred, state->BindExpr(Ex, LCtx, V, true)); |
| } |
| |
| void ExprEngine:: |
| VisitOffsetOfExpr(const OffsetOfExpr *OOE, |
| ExplodedNode *Pred, ExplodedNodeSet &Dst) { |
| StmtNodeBuilder B(Pred, Dst, *currBldrCtx); |
| 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, *currBldrCtx); |
| |
| 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, *currBldrCtx); |
| 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->isGLValue()); |
| // 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->isGLValue()); |
| 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(V.castAs<NonLoc>())); |
| break; |
| case UO_Minus: |
| // FIXME: Do we need to handle promotions? |
| state = state->BindExpr(U, LCtx, evalMinus(V.castAs<NonLoc>())); |
| 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 (Optional<Loc> LV = V.getAs<Loc>()) { |
| Loc X = svalBuilder.makeNull(); |
| Result = evalBinOp(state, BO_EQ, *LV, X, U->getType()); |
| } |
| else if (Ex->getType()->isFloatingType()) { |
| // FIXME: handle floating point types. |
| Result = UnknownVal(); |
| } else { |
| nonloc::ConcreteInt X(getBasicVals().getValue(0, Ex->getType())); |
| Result = evalBinOp(state, BO_EQ, V.castAs<NonLoc>(), 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, *currBldrCtx); |
| 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 = V2_untested.castAs<DefinedSVal>(); |
| |
| // 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 if (U->getType()->isIntegralOrEnumerationType()) |
| RHS = svalBuilder.makeIntVal(1, U->getType()); |
| else |
| RHS = UnknownVal(); |
| |
| SVal Result = evalBinOp(state, Op, V2, RHS, U->getType()); |
| |
| // Conjure a new symbol if necessary to recover precision. |
| if (Result.isUnknown()){ |
| DefinedOrUnknownSVal SymVal = |
| svalBuilder.conjureSymbolVal(0, Ex, LCtx, currBldrCtx->blockCount()); |
| 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->isGLValue()) |
| 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); |
| } |
