// SimpleSValBuilder.cpp - A basic SValBuilder -----------------------*- 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 SimpleSValBuilder, a basic implementation of SValBuilder. // //===----------------------------------------------------------------------===// #include "clang/StaticAnalyzer/Core/PathSensitive/SValBuilder.h" #include "clang/StaticAnalyzer/Core/PathSensitive/APSIntType.h" #include "clang/StaticAnalyzer/Core/PathSensitive/ProgramState.h" using namespace clang; using namespace ento; namespace { class SimpleSValBuilder : public SValBuilder { protected: SVal dispatchCast(SVal val, QualType castTy) override; SVal evalCastFromNonLoc(NonLoc val, QualType castTy) override; SVal evalCastFromLoc(Loc val, QualType castTy) override; public: SimpleSValBuilder(llvm::BumpPtrAllocator &alloc, ASTContext &context, ProgramStateManager &stateMgr) : SValBuilder(alloc, context, stateMgr) {} virtual ~SimpleSValBuilder() {} SVal evalMinus(NonLoc val) override; SVal evalComplement(NonLoc val) override; SVal evalBinOpNN(ProgramStateRef state, BinaryOperator::Opcode op, NonLoc lhs, NonLoc rhs, QualType resultTy) override; SVal evalBinOpLL(ProgramStateRef state, BinaryOperator::Opcode op, Loc lhs, Loc rhs, QualType resultTy) override; SVal evalBinOpLN(ProgramStateRef state, BinaryOperator::Opcode op, Loc lhs, NonLoc rhs, QualType resultTy) override; /// getKnownValue - evaluates a given SVal. If the SVal has only one possible /// (integer) value, that value is returned. Otherwise, returns NULL. const llvm::APSInt *getKnownValue(ProgramStateRef state, SVal V) override; SVal MakeSymIntVal(const SymExpr *LHS, BinaryOperator::Opcode op, const llvm::APSInt &RHS, QualType resultTy); }; } // end anonymous namespace SValBuilder *ento::createSimpleSValBuilder(llvm::BumpPtrAllocator &alloc, ASTContext &context, ProgramStateManager &stateMgr) { return new SimpleSValBuilder(alloc, context, stateMgr); } //===----------------------------------------------------------------------===// // Transfer function for Casts. //===----------------------------------------------------------------------===// SVal SimpleSValBuilder::dispatchCast(SVal Val, QualType CastTy) { assert(Val.getAs<Loc>() || Val.getAs<NonLoc>()); return Val.getAs<Loc>() ? evalCastFromLoc(Val.castAs<Loc>(), CastTy) : evalCastFromNonLoc(Val.castAs<NonLoc>(), CastTy); } SVal SimpleSValBuilder::evalCastFromNonLoc(NonLoc val, QualType castTy) { bool isLocType = Loc::isLocType(castTy); if (Optional<nonloc::LocAsInteger> LI = val.getAs<nonloc::LocAsInteger>()) { if (isLocType) return LI->getLoc(); // FIXME: Correctly support promotions/truncations. unsigned castSize = Context.getTypeSize(castTy); if (castSize == LI->getNumBits()) return val; return makeLocAsInteger(LI->getLoc(), castSize); } if (const SymExpr *se = val.getAsSymbolicExpression()) { QualType T = Context.getCanonicalType(se->getType()); // If types are the same or both are integers, ignore the cast. // FIXME: Remove this hack when we support symbolic truncation/extension. // HACK: If both castTy and T are integers, ignore the cast. This is // not a permanent solution. Eventually we want to precisely handle // extension/truncation of symbolic integers. This prevents us from losing // precision when we assign 'x = y' and 'y' is symbolic and x and y are // different integer types. if (haveSameType(T, castTy)) return val; if (!isLocType) return makeNonLoc(se, T, castTy); return UnknownVal(); } // If value is a non-integer constant, produce unknown. if (!val.getAs<nonloc::ConcreteInt>()) return UnknownVal(); // Handle casts to a boolean type. if (castTy->isBooleanType()) { bool b = val.castAs<nonloc::ConcreteInt>().getValue().getBoolValue(); return makeTruthVal(b, castTy); } // Only handle casts from integers to integers - if val is an integer constant // being cast to a non-integer type, produce unknown. if (!isLocType && !castTy->isIntegralOrEnumerationType()) return UnknownVal(); llvm::APSInt i = val.castAs<nonloc::ConcreteInt>().getValue(); BasicVals.getAPSIntType(castTy).apply(i); if (isLocType) return makeIntLocVal(i); else return makeIntVal(i); } SVal SimpleSValBuilder::evalCastFromLoc(Loc val, QualType castTy) { // Casts from pointers -> pointers, just return the lval. // // Casts from pointers -> references, just return the lval. These // can be introduced by the frontend for corner cases, e.g // casting from va_list* to __builtin_va_list&. // if (Loc::isLocType(castTy) || castTy->isReferenceType()) return val; // FIXME: Handle transparent unions where a value can be "transparently" // lifted into a union type. if (castTy->isUnionType()) return UnknownVal(); // Casting a Loc to a bool will almost always be true, // unless this is a weak function or a symbolic region. if (castTy->isBooleanType()) { switch (val.getSubKind()) { case loc::MemRegionKind: { const MemRegion *R = val.castAs<loc::MemRegionVal>().getRegion(); if (const FunctionTextRegion *FTR = dyn_cast<FunctionTextRegion>(R)) if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(FTR->getDecl())) if (FD->isWeak()) // FIXME: Currently we are using an extent symbol here, // because there are no generic region address metadata // symbols to use, only content metadata. return nonloc::SymbolVal(SymMgr.getExtentSymbol(FTR)); if (const SymbolicRegion *SymR = R->getSymbolicBase()) return nonloc::SymbolVal(SymR->getSymbol()); // FALL-THROUGH } case loc::GotoLabelKind: // Labels and non-symbolic memory regions are always true. return makeTruthVal(true, castTy); } } if (castTy->isIntegralOrEnumerationType()) { unsigned BitWidth = Context.getTypeSize(castTy); if (!val.getAs<loc::ConcreteInt>()) return makeLocAsInteger(val, BitWidth); llvm::APSInt i = val.castAs<loc::ConcreteInt>().getValue(); BasicVals.getAPSIntType(castTy).apply(i); return makeIntVal(i); } // All other cases: return 'UnknownVal'. This includes casting pointers // to floats, which is probably badness it itself, but this is a good // intermediate solution until we do something better. return UnknownVal(); } //===----------------------------------------------------------------------===// // Transfer function for unary operators. //===----------------------------------------------------------------------===// SVal SimpleSValBuilder::evalMinus(NonLoc val) { switch (val.getSubKind()) { case nonloc::ConcreteIntKind: return val.castAs<nonloc::ConcreteInt>().evalMinus(*this); default: return UnknownVal(); } } SVal SimpleSValBuilder::evalComplement(NonLoc X) { switch (X.getSubKind()) { case nonloc::ConcreteIntKind: return X.castAs<nonloc::ConcreteInt>().evalComplement(*this); default: return UnknownVal(); } } //===----------------------------------------------------------------------===// // Transfer function for binary operators. //===----------------------------------------------------------------------===// SVal SimpleSValBuilder::MakeSymIntVal(const SymExpr *LHS, BinaryOperator::Opcode op, const llvm::APSInt &RHS, QualType resultTy) { bool isIdempotent = false; // Check for a few special cases with known reductions first. switch (op) { default: // We can't reduce this case; just treat it normally. break; case BO_Mul: // a*0 and a*1 if (RHS == 0) return makeIntVal(0, resultTy); else if (RHS == 1) isIdempotent = true; break; case BO_Div: // a/0 and a/1 if (RHS == 0) // This is also handled elsewhere. return UndefinedVal(); else if (RHS == 1) isIdempotent = true; break; case BO_Rem: // a%0 and a%1 if (RHS == 0) // This is also handled elsewhere. return UndefinedVal(); else if (RHS == 1) return makeIntVal(0, resultTy); break; case BO_Add: case BO_Sub: case BO_Shl: case BO_Shr: case BO_Xor: // a+0, a-0, a<<0, a>>0, a^0 if (RHS == 0) isIdempotent = true; break; case BO_And: // a&0 and a&(~0) if (RHS == 0) return makeIntVal(0, resultTy); else if (RHS.isAllOnesValue()) isIdempotent = true; break; case BO_Or: // a|0 and a|(~0) if (RHS == 0) isIdempotent = true; else if (RHS.isAllOnesValue()) { const llvm::APSInt &Result = BasicVals.Convert(resultTy, RHS); return nonloc::ConcreteInt(Result); } break; } // Idempotent ops (like a*1) can still change the type of an expression. // Wrap the LHS up in a NonLoc again and let evalCastFromNonLoc do the // dirty work. if (isIdempotent) return evalCastFromNonLoc(nonloc::SymbolVal(LHS), resultTy); // If we reach this point, the expression cannot be simplified. // Make a SymbolVal for the entire expression, after converting the RHS. const llvm::APSInt *ConvertedRHS = &RHS; if (BinaryOperator::isComparisonOp(op)) { // We're looking for a type big enough to compare the symbolic value // with the given constant. // FIXME: This is an approximation of Sema::UsualArithmeticConversions. ASTContext &Ctx = getContext(); QualType SymbolType = LHS->getType(); uint64_t ValWidth = RHS.getBitWidth(); uint64_t TypeWidth = Ctx.getTypeSize(SymbolType); if (ValWidth < TypeWidth) { // If the value is too small, extend it. ConvertedRHS = &BasicVals.Convert(SymbolType, RHS); } else if (ValWidth == TypeWidth) { // If the value is signed but the symbol is unsigned, do the comparison // in unsigned space. [C99 6.3.1.8] // (For the opposite case, the value is already unsigned.) if (RHS.isSigned() && !SymbolType->isSignedIntegerOrEnumerationType()) ConvertedRHS = &BasicVals.Convert(SymbolType, RHS); } } else ConvertedRHS = &BasicVals.Convert(resultTy, RHS); return makeNonLoc(LHS, op, *ConvertedRHS, resultTy); } SVal SimpleSValBuilder::evalBinOpNN(ProgramStateRef state, BinaryOperator::Opcode op, NonLoc lhs, NonLoc rhs, QualType resultTy) { NonLoc InputLHS = lhs; NonLoc InputRHS = rhs; // Handle trivial case where left-side and right-side are the same. if (lhs == rhs) switch (op) { default: break; case BO_EQ: case BO_LE: case BO_GE: return makeTruthVal(true, resultTy); case BO_LT: case BO_GT: case BO_NE: return makeTruthVal(false, resultTy); case BO_Xor: case BO_Sub: if (resultTy->isIntegralOrEnumerationType()) return makeIntVal(0, resultTy); return evalCastFromNonLoc(makeIntVal(0, /*Unsigned=*/false), resultTy); case BO_Or: case BO_And: return evalCastFromNonLoc(lhs, resultTy); } while (1) { switch (lhs.getSubKind()) { default: return makeSymExprValNN(state, op, lhs, rhs, resultTy); case nonloc::LocAsIntegerKind: { Loc lhsL = lhs.castAs<nonloc::LocAsInteger>().getLoc(); switch (rhs.getSubKind()) { case nonloc::LocAsIntegerKind: return evalBinOpLL(state, op, lhsL, rhs.castAs<nonloc::LocAsInteger>().getLoc(), resultTy); case nonloc::ConcreteIntKind: { // Transform the integer into a location and compare. llvm::APSInt i = rhs.castAs<nonloc::ConcreteInt>().getValue(); BasicVals.getAPSIntType(Context.VoidPtrTy).apply(i); return evalBinOpLL(state, op, lhsL, makeLoc(i), resultTy); } default: switch (op) { case BO_EQ: return makeTruthVal(false, resultTy); case BO_NE: return makeTruthVal(true, resultTy); default: // This case also handles pointer arithmetic. return makeSymExprValNN(state, op, InputLHS, InputRHS, resultTy); } } } case nonloc::ConcreteIntKind: { llvm::APSInt LHSValue = lhs.castAs<nonloc::ConcreteInt>().getValue(); // If we're dealing with two known constants, just perform the operation. if (const llvm::APSInt *KnownRHSValue = getKnownValue(state, rhs)) { llvm::APSInt RHSValue = *KnownRHSValue; if (BinaryOperator::isComparisonOp(op)) { // We're looking for a type big enough to compare the two values. // FIXME: This is not correct. char + short will result in a promotion // to int. Unfortunately we have lost types by this point. APSIntType CompareType = std::max(APSIntType(LHSValue), APSIntType(RHSValue)); CompareType.apply(LHSValue); CompareType.apply(RHSValue); } else if (!BinaryOperator::isShiftOp(op)) { APSIntType IntType = BasicVals.getAPSIntType(resultTy); IntType.apply(LHSValue); IntType.apply(RHSValue); } const llvm::APSInt *Result = BasicVals.evalAPSInt(op, LHSValue, RHSValue); if (!Result) return UndefinedVal(); return nonloc::ConcreteInt(*Result); } // Swap the left and right sides and flip the operator if doing so // allows us to better reason about the expression (this is a form // of expression canonicalization). // While we're at it, catch some special cases for non-commutative ops. switch (op) { case BO_LT: case BO_GT: case BO_LE: case BO_GE: op = BinaryOperator::reverseComparisonOp(op); // FALL-THROUGH case BO_EQ: case BO_NE: case BO_Add: case BO_Mul: case BO_And: case BO_Xor: case BO_Or: std::swap(lhs, rhs); continue; case BO_Shr: // (~0)>>a if (LHSValue.isAllOnesValue() && LHSValue.isSigned()) return evalCastFromNonLoc(lhs, resultTy); // FALL-THROUGH case BO_Shl: // 0<<a and 0>>a if (LHSValue == 0) return evalCastFromNonLoc(lhs, resultTy); return makeSymExprValNN(state, op, InputLHS, InputRHS, resultTy); default: return makeSymExprValNN(state, op, InputLHS, InputRHS, resultTy); } } case nonloc::SymbolValKind: { // We only handle LHS as simple symbols or SymIntExprs. SymbolRef Sym = lhs.castAs<nonloc::SymbolVal>().getSymbol(); // LHS is a symbolic expression. if (const SymIntExpr *symIntExpr = dyn_cast<SymIntExpr>(Sym)) { // Is this a logical not? (!x is represented as x == 0.) if (op == BO_EQ && rhs.isZeroConstant()) { // We know how to negate certain expressions. Simplify them here. BinaryOperator::Opcode opc = symIntExpr->getOpcode(); switch (opc) { default: // We don't know how to negate this operation. // Just handle it as if it were a normal comparison to 0. break; case BO_LAnd: case BO_LOr: llvm_unreachable("Logical operators handled by branching logic."); case BO_Assign: case BO_MulAssign: case BO_DivAssign: case BO_RemAssign: case BO_AddAssign: case BO_SubAssign: case BO_ShlAssign: case BO_ShrAssign: case BO_AndAssign: case BO_XorAssign: case BO_OrAssign: case BO_Comma: llvm_unreachable("'=' and ',' operators handled by ExprEngine."); case BO_PtrMemD: case BO_PtrMemI: llvm_unreachable("Pointer arithmetic not handled here."); case BO_LT: case BO_GT: case BO_LE: case BO_GE: case BO_EQ: case BO_NE: assert(resultTy->isBooleanType() || resultTy == getConditionType()); assert(symIntExpr->getType()->isBooleanType() || getContext().hasSameUnqualifiedType(symIntExpr->getType(), getConditionType())); // Negate the comparison and make a value. opc = BinaryOperator::negateComparisonOp(opc); return makeNonLoc(symIntExpr->getLHS(), opc, symIntExpr->getRHS(), resultTy); } } // For now, only handle expressions whose RHS is a constant. if (const llvm::APSInt *RHSValue = getKnownValue(state, rhs)) { // If both the LHS and the current expression are additive, // fold their constants and try again. if (BinaryOperator::isAdditiveOp(op)) { BinaryOperator::Opcode lop = symIntExpr->getOpcode(); if (BinaryOperator::isAdditiveOp(lop)) { // Convert the two constants to a common type, then combine them. // resultTy may not be the best type to convert to, but it's // probably the best choice in expressions with mixed type // (such as x+1U+2LL). The rules for implicit conversions should // choose a reasonable type to preserve the expression, and will // at least match how the value is going to be used. APSIntType IntType = BasicVals.getAPSIntType(resultTy); const llvm::APSInt &first = IntType.convert(symIntExpr->getRHS()); const llvm::APSInt &second = IntType.convert(*RHSValue); const llvm::APSInt *newRHS; if (lop == op) newRHS = BasicVals.evalAPSInt(BO_Add, first, second); else newRHS = BasicVals.evalAPSInt(BO_Sub, first, second); assert(newRHS && "Invalid operation despite common type!"); rhs = nonloc::ConcreteInt(*newRHS); lhs = nonloc::SymbolVal(symIntExpr->getLHS()); op = lop; continue; } } // Otherwise, make a SymIntExpr out of the expression. return MakeSymIntVal(symIntExpr, op, *RHSValue, resultTy); } } // Does the symbolic expression simplify to a constant? // If so, "fold" the constant by setting 'lhs' to a ConcreteInt // and try again. ConstraintManager &CMgr = state->getConstraintManager(); if (const llvm::APSInt *Constant = CMgr.getSymVal(state, Sym)) { lhs = nonloc::ConcreteInt(*Constant); continue; } // Is the RHS a constant? if (const llvm::APSInt *RHSValue = getKnownValue(state, rhs)) return MakeSymIntVal(Sym, op, *RHSValue, resultTy); // Give up -- this is not a symbolic expression we can handle. return makeSymExprValNN(state, op, InputLHS, InputRHS, resultTy); } } } } static SVal evalBinOpFieldRegionFieldRegion(const FieldRegion *LeftFR, const FieldRegion *RightFR, BinaryOperator::Opcode op, QualType resultTy, SimpleSValBuilder &SVB) { // Only comparisons are meaningful here! if (!BinaryOperator::isComparisonOp(op)) return UnknownVal(); // Next, see if the two FRs have the same super-region. // FIXME: This doesn't handle casts yet, and simply stripping the casts // doesn't help. if (LeftFR->getSuperRegion() != RightFR->getSuperRegion()) return UnknownVal(); const FieldDecl *LeftFD = LeftFR->getDecl(); const FieldDecl *RightFD = RightFR->getDecl(); const RecordDecl *RD = LeftFD->getParent(); // Make sure the two FRs are from the same kind of record. Just in case! // FIXME: This is probably where inheritance would be a problem. if (RD != RightFD->getParent()) return UnknownVal(); // We know for sure that the two fields are not the same, since that // would have given us the same SVal. if (op == BO_EQ) return SVB.makeTruthVal(false, resultTy); if (op == BO_NE) return SVB.makeTruthVal(true, resultTy); // Iterate through the fields and see which one comes first. // [C99 6.7.2.1.13] "Within a structure object, the non-bit-field // members and the units in which bit-fields reside have addresses that // increase in the order in which they are declared." bool leftFirst = (op == BO_LT || op == BO_LE); for (const auto *I : RD->fields()) { if (I == LeftFD) return SVB.makeTruthVal(leftFirst, resultTy); if (I == RightFD) return SVB.makeTruthVal(!leftFirst, resultTy); } llvm_unreachable("Fields not found in parent record's definition"); } // FIXME: all this logic will change if/when we have MemRegion::getLocation(). SVal SimpleSValBuilder::evalBinOpLL(ProgramStateRef state, BinaryOperator::Opcode op, Loc lhs, Loc rhs, QualType resultTy) { // Only comparisons and subtractions are valid operations on two pointers. // See [C99 6.5.5 through 6.5.14] or [C++0x 5.6 through 5.15]. // However, if a pointer is casted to an integer, evalBinOpNN may end up // calling this function with another operation (PR7527). We don't attempt to // model this for now, but it could be useful, particularly when the // "location" is actually an integer value that's been passed through a void*. if (!(BinaryOperator::isComparisonOp(op) || op == BO_Sub)) return UnknownVal(); // Special cases for when both sides are identical. if (lhs == rhs) { switch (op) { default: llvm_unreachable("Unimplemented operation for two identical values"); case BO_Sub: return makeZeroVal(resultTy); case BO_EQ: case BO_LE: case BO_GE: return makeTruthVal(true, resultTy); case BO_NE: case BO_LT: case BO_GT: return makeTruthVal(false, resultTy); } } switch (lhs.getSubKind()) { default: llvm_unreachable("Ordering not implemented for this Loc."); case loc::GotoLabelKind: // The only thing we know about labels is that they're non-null. if (rhs.isZeroConstant()) { switch (op) { default: break; case BO_Sub: return evalCastFromLoc(lhs, resultTy); case BO_EQ: case BO_LE: case BO_LT: return makeTruthVal(false, resultTy); case BO_NE: case BO_GT: case BO_GE: return makeTruthVal(true, resultTy); } } // There may be two labels for the same location, and a function region may // have the same address as a label at the start of the function (depending // on the ABI). // FIXME: we can probably do a comparison against other MemRegions, though. // FIXME: is there a way to tell if two labels refer to the same location? return UnknownVal(); case loc::ConcreteIntKind: { // If one of the operands is a symbol and the other is a constant, // build an expression for use by the constraint manager. if (SymbolRef rSym = rhs.getAsLocSymbol()) { // We can only build expressions with symbols on the left, // so we need a reversible operator. if (!BinaryOperator::isComparisonOp(op)) return UnknownVal(); const llvm::APSInt &lVal = lhs.castAs<loc::ConcreteInt>().getValue(); op = BinaryOperator::reverseComparisonOp(op); return makeNonLoc(rSym, op, lVal, resultTy); } // If both operands are constants, just perform the operation. if (Optional<loc::ConcreteInt> rInt = rhs.getAs<loc::ConcreteInt>()) { SVal ResultVal = lhs.castAs<loc::ConcreteInt>().evalBinOp(BasicVals, op, *rInt); if (Optional<NonLoc> Result = ResultVal.getAs<NonLoc>()) return evalCastFromNonLoc(*Result, resultTy); assert(!ResultVal.getAs<Loc>() && "Loc-Loc ops should not produce Locs"); return UnknownVal(); } // Special case comparisons against NULL. // This must come after the test if the RHS is a symbol, which is used to // build constraints. The address of any non-symbolic region is guaranteed // to be non-NULL, as is any label. assert(rhs.getAs<loc::MemRegionVal>() || rhs.getAs<loc::GotoLabel>()); if (lhs.isZeroConstant()) { switch (op) { default: break; case BO_EQ: case BO_GT: case BO_GE: return makeTruthVal(false, resultTy); case BO_NE: case BO_LT: case BO_LE: return makeTruthVal(true, resultTy); } } // Comparing an arbitrary integer to a region or label address is // completely unknowable. return UnknownVal(); } case loc::MemRegionKind: { if (Optional<loc::ConcreteInt> rInt = rhs.getAs<loc::ConcreteInt>()) { // If one of the operands is a symbol and the other is a constant, // build an expression for use by the constraint manager. if (SymbolRef lSym = lhs.getAsLocSymbol(true)) return MakeSymIntVal(lSym, op, rInt->getValue(), resultTy); // Special case comparisons to NULL. // This must come after the test if the LHS is a symbol, which is used to // build constraints. The address of any non-symbolic region is guaranteed // to be non-NULL. if (rInt->isZeroConstant()) { if (op == BO_Sub) return evalCastFromLoc(lhs, resultTy); if (BinaryOperator::isComparisonOp(op)) { QualType boolType = getContext().BoolTy; NonLoc l = evalCastFromLoc(lhs, boolType).castAs<NonLoc>(); NonLoc r = makeTruthVal(false, boolType).castAs<NonLoc>(); return evalBinOpNN(state, op, l, r, resultTy); } } // Comparing a region to an arbitrary integer is completely unknowable. return UnknownVal(); } // Get both values as regions, if possible. const MemRegion *LeftMR = lhs.getAsRegion(); assert(LeftMR && "MemRegionKind SVal doesn't have a region!"); const MemRegion *RightMR = rhs.getAsRegion(); if (!RightMR) // The RHS is probably a label, which in theory could address a region. // FIXME: we can probably make a more useful statement about non-code // regions, though. return UnknownVal(); const MemRegion *LeftBase = LeftMR->getBaseRegion(); const MemRegion *RightBase = RightMR->getBaseRegion(); const MemSpaceRegion *LeftMS = LeftBase->getMemorySpace(); const MemSpaceRegion *RightMS = RightBase->getMemorySpace(); const MemSpaceRegion *UnknownMS = MemMgr.getUnknownRegion(); // If the two regions are from different known memory spaces they cannot be // equal. Also, assume that no symbolic region (whose memory space is // unknown) is on the stack. if (LeftMS != RightMS && ((LeftMS != UnknownMS && RightMS != UnknownMS) || (isa<StackSpaceRegion>(LeftMS) || isa<StackSpaceRegion>(RightMS)))) { switch (op) { default: return UnknownVal(); case BO_EQ: return makeTruthVal(false, resultTy); case BO_NE: return makeTruthVal(true, resultTy); } } // If both values wrap regions, see if they're from different base regions. // Note, heap base symbolic regions are assumed to not alias with // each other; for example, we assume that malloc returns different address // on each invocation. if (LeftBase != RightBase && ((!isa<SymbolicRegion>(LeftBase) && !isa<SymbolicRegion>(RightBase)) || (isa<HeapSpaceRegion>(LeftMS) || isa<HeapSpaceRegion>(RightMS))) ){ switch (op) { default: return UnknownVal(); case BO_EQ: return makeTruthVal(false, resultTy); case BO_NE: return makeTruthVal(true, resultTy); } } // Handle special cases for when both regions are element regions. const ElementRegion *RightER = dyn_cast<ElementRegion>(RightMR); const ElementRegion *LeftER = dyn_cast<ElementRegion>(LeftMR); if (RightER && LeftER) { // Next, see if the two ERs have the same super-region and matching types. // FIXME: This should do something useful even if the types don't match, // though if both indexes are constant the RegionRawOffset path will // give the correct answer. if (LeftER->getSuperRegion() == RightER->getSuperRegion() && LeftER->getElementType() == RightER->getElementType()) { // Get the left index and cast it to the correct type. // If the index is unknown or undefined, bail out here. SVal LeftIndexVal = LeftER->getIndex(); Optional<NonLoc> LeftIndex = LeftIndexVal.getAs<NonLoc>(); if (!LeftIndex) return UnknownVal(); LeftIndexVal = evalCastFromNonLoc(*LeftIndex, ArrayIndexTy); LeftIndex = LeftIndexVal.getAs<NonLoc>(); if (!LeftIndex) return UnknownVal(); // Do the same for the right index. SVal RightIndexVal = RightER->getIndex(); Optional<NonLoc> RightIndex = RightIndexVal.getAs<NonLoc>(); if (!RightIndex) return UnknownVal(); RightIndexVal = evalCastFromNonLoc(*RightIndex, ArrayIndexTy); RightIndex = RightIndexVal.getAs<NonLoc>(); if (!RightIndex) return UnknownVal(); // Actually perform the operation. // evalBinOpNN expects the two indexes to already be the right type. return evalBinOpNN(state, op, *LeftIndex, *RightIndex, resultTy); } } // Special handling of the FieldRegions, even with symbolic offsets. const FieldRegion *RightFR = dyn_cast<FieldRegion>(RightMR); const FieldRegion *LeftFR = dyn_cast<FieldRegion>(LeftMR); if (RightFR && LeftFR) { SVal R = evalBinOpFieldRegionFieldRegion(LeftFR, RightFR, op, resultTy, *this); if (!R.isUnknown()) return R; } // Compare the regions using the raw offsets. RegionOffset LeftOffset = LeftMR->getAsOffset(); RegionOffset RightOffset = RightMR->getAsOffset(); if (LeftOffset.getRegion() != nullptr && LeftOffset.getRegion() == RightOffset.getRegion() && !LeftOffset.hasSymbolicOffset() && !RightOffset.hasSymbolicOffset()) { int64_t left = LeftOffset.getOffset(); int64_t right = RightOffset.getOffset(); switch (op) { default: return UnknownVal(); case BO_LT: return makeTruthVal(left < right, resultTy); case BO_GT: return makeTruthVal(left > right, resultTy); case BO_LE: return makeTruthVal(left <= right, resultTy); case BO_GE: return makeTruthVal(left >= right, resultTy); case BO_EQ: return makeTruthVal(left == right, resultTy); case BO_NE: return makeTruthVal(left != right, resultTy); } } // At this point we're not going to get a good answer, but we can try // conjuring an expression instead. SymbolRef LHSSym = lhs.getAsLocSymbol(); SymbolRef RHSSym = rhs.getAsLocSymbol(); if (LHSSym && RHSSym) return makeNonLoc(LHSSym, op, RHSSym, resultTy); // If we get here, we have no way of comparing the regions. return UnknownVal(); } } } SVal SimpleSValBuilder::evalBinOpLN(ProgramStateRef state, BinaryOperator::Opcode op, Loc lhs, NonLoc rhs, QualType resultTy) { assert(!BinaryOperator::isComparisonOp(op) && "arguments to comparison ops must be of the same type"); // Special case: rhs is a zero constant. if (rhs.isZeroConstant()) return lhs; // We are dealing with pointer arithmetic. // Handle pointer arithmetic on constant values. if (Optional<nonloc::ConcreteInt> rhsInt = rhs.getAs<nonloc::ConcreteInt>()) { if (Optional<loc::ConcreteInt> lhsInt = lhs.getAs<loc::ConcreteInt>()) { const llvm::APSInt &leftI = lhsInt->getValue(); assert(leftI.isUnsigned()); llvm::APSInt rightI(rhsInt->getValue(), /* isUnsigned */ true); // Convert the bitwidth of rightI. This should deal with overflow // since we are dealing with concrete values. rightI = rightI.extOrTrunc(leftI.getBitWidth()); // Offset the increment by the pointer size. llvm::APSInt Multiplicand(rightI.getBitWidth(), /* isUnsigned */ true); rightI *= Multiplicand; // Compute the adjusted pointer. switch (op) { case BO_Add: rightI = leftI + rightI; break; case BO_Sub: rightI = leftI - rightI; break; default: llvm_unreachable("Invalid pointer arithmetic operation"); } return loc::ConcreteInt(getBasicValueFactory().getValue(rightI)); } } // Handle cases where 'lhs' is a region. if (const MemRegion *region = lhs.getAsRegion()) { rhs = convertToArrayIndex(rhs).castAs<NonLoc>(); SVal index = UnknownVal(); const MemRegion *superR = nullptr; QualType elementType; if (const ElementRegion *elemReg = dyn_cast<ElementRegion>(region)) { assert(op == BO_Add || op == BO_Sub); index = evalBinOpNN(state, op, elemReg->getIndex(), rhs, getArrayIndexType()); superR = elemReg->getSuperRegion(); elementType = elemReg->getElementType(); } else if (isa<SubRegion>(region)) { superR = region; index = rhs; if (resultTy->isAnyPointerType()) elementType = resultTy->getPointeeType(); } if (Optional<NonLoc> indexV = index.getAs<NonLoc>()) { return loc::MemRegionVal(MemMgr.getElementRegion(elementType, *indexV, superR, getContext())); } } return UnknownVal(); } const llvm::APSInt *SimpleSValBuilder::getKnownValue(ProgramStateRef state, SVal V) { if (V.isUnknownOrUndef()) return nullptr; if (Optional<loc::ConcreteInt> X = V.getAs<loc::ConcreteInt>()) return &X->getValue(); if (Optional<nonloc::ConcreteInt> X = V.getAs<nonloc::ConcreteInt>()) return &X->getValue(); if (SymbolRef Sym = V.getAsSymbol()) return state->getConstraintManager().getSymVal(state, Sym); // FIXME: Add support for SymExprs. return nullptr; }