| // 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/APSIntType.h" |
| #include "clang/StaticAnalyzer/Core/PathSensitive/SValBuilder.h" |
| #include "clang/StaticAnalyzer/Core/PathSensitive/ProgramState.h" |
| |
| using namespace clang; |
| using namespace ento; |
| |
| namespace { |
| class SimpleSValBuilder : public SValBuilder { |
| protected: |
| virtual SVal dispatchCast(SVal val, QualType castTy); |
| virtual SVal evalCastFromNonLoc(NonLoc val, QualType castTy); |
| virtual SVal evalCastFromLoc(Loc val, QualType castTy); |
| |
| public: |
| SimpleSValBuilder(llvm::BumpPtrAllocator &alloc, ASTContext &context, |
| ProgramStateManager &stateMgr) |
| : SValBuilder(alloc, context, stateMgr) {} |
| virtual ~SimpleSValBuilder() {} |
| |
| virtual SVal evalMinus(NonLoc val); |
| virtual SVal evalComplement(NonLoc val); |
| virtual SVal evalBinOpNN(ProgramStateRef state, BinaryOperator::Opcode op, |
| NonLoc lhs, NonLoc rhs, QualType resultTy); |
| virtual SVal evalBinOpLL(ProgramStateRef state, BinaryOperator::Opcode op, |
| Loc lhs, Loc rhs, QualType resultTy); |
| virtual SVal evalBinOpLN(ProgramStateRef state, BinaryOperator::Opcode op, |
| Loc lhs, NonLoc rhs, QualType resultTy); |
| |
| /// getKnownValue - evaluates a given SVal. If the SVal has only one possible |
| /// (integer) value, that value is returned. Otherwise, returns NULL. |
| virtual const llvm::APSInt *getKnownValue(ProgramStateRef state, SVal V); |
| |
| 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(isa<Loc>(&Val) || isa<NonLoc>(&Val)); |
| return isa<Loc>(Val) ? evalCastFromLoc(cast<Loc>(Val), CastTy) |
| : evalCastFromNonLoc(cast<NonLoc>(Val), CastTy); |
| } |
| |
| SVal SimpleSValBuilder::evalCastFromNonLoc(NonLoc val, QualType castTy) { |
| |
| bool isLocType = Loc::isLocType(castTy); |
| |
| if (nonloc::LocAsInteger *LI = dyn_cast<nonloc::LocAsInteger>(&val)) { |
| 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(Context)); |
| // 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 (!isa<nonloc::ConcreteInt>(val)) |
| return UnknownVal(); |
| |
| // 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->isIntegerType()) |
| return UnknownVal(); |
| |
| llvm::APSInt i = cast<nonloc::ConcreteInt>(val).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(); |
| |
| if (castTy->isIntegerType()) { |
| unsigned BitWidth = Context.getTypeSize(castTy); |
| |
| if (!isa<loc::ConcreteInt>(val)) |
| return makeLocAsInteger(val, BitWidth); |
| |
| llvm::APSInt i = cast<loc::ConcreteInt>(val).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 cast<nonloc::ConcreteInt>(val).evalMinus(*this); |
| default: |
| return UnknownVal(); |
| } |
| } |
| |
| SVal SimpleSValBuilder::evalComplement(NonLoc X) { |
| switch (X.getSubKind()) { |
| case nonloc::ConcreteIntKind: |
| return cast<nonloc::ConcreteInt>(X).evalComplement(*this); |
| default: |
| return UnknownVal(); |
| } |
| } |
| |
| //===----------------------------------------------------------------------===// |
| // Transfer function for binary operators. |
| //===----------------------------------------------------------------------===// |
| |
| static BinaryOperator::Opcode NegateComparison(BinaryOperator::Opcode op) { |
| switch (op) { |
| default: |
| llvm_unreachable("Invalid opcode."); |
| case BO_LT: return BO_GE; |
| case BO_GT: return BO_LE; |
| case BO_LE: return BO_GT; |
| case BO_GE: return BO_LT; |
| case BO_EQ: return BO_NE; |
| case BO_NE: return BO_EQ; |
| } |
| } |
| |
| static BinaryOperator::Opcode ReverseComparison(BinaryOperator::Opcode op) { |
| switch (op) { |
| default: |
| llvm_unreachable("Invalid opcode."); |
| case BO_LT: return BO_GT; |
| case BO_GT: return BO_LT; |
| case BO_LE: return BO_GE; |
| case BO_GE: return BO_LE; |
| case BO_EQ: |
| case BO_NE: |
| return op; |
| } |
| } |
| |
| 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(Ctx); |
| 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: |
| return makeIntVal(0, 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 = cast<nonloc::LocAsInteger>(lhs).getLoc(); |
| switch (rhs.getSubKind()) { |
| case nonloc::LocAsIntegerKind: |
| return evalBinOpLL(state, op, lhsL, |
| cast<nonloc::LocAsInteger>(rhs).getLoc(), |
| resultTy); |
| case nonloc::ConcreteIntKind: { |
| // Transform the integer into a location and compare. |
| llvm::APSInt i = cast<nonloc::ConcreteInt>(rhs).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 = cast<nonloc::ConcreteInt>(lhs).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 = ReverseComparison(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 = cast<nonloc::SymbolVal>(lhs).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: |
| // Negate the comparison and make a value. |
| opc = NegateComparison(opc); |
| assert(symIntExpr->getType(Context) == resultTy); |
| 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); |
| } |
| |
| |
| } else if (isa<SymbolData>(Sym)) { |
| // Does the symbol simplify to a constant? If so, "fold" the constant |
| // by setting 'lhs' to a ConcreteInt and try again. |
| if (const llvm::APSInt *Constant = state->getSymVal(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); |
| } |
| } |
| } |
| } |
| |
| // 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 = cast<loc::ConcreteInt>(lhs).getValue(); |
| return makeNonLoc(rSym, ReverseComparison(op), lVal, resultTy); |
| } |
| |
| // If both operands are constants, just perform the operation. |
| if (loc::ConcreteInt *rInt = dyn_cast<loc::ConcreteInt>(&rhs)) { |
| SVal ResultVal = cast<loc::ConcreteInt>(lhs).evalBinOp(BasicVals, op, |
| *rInt); |
| if (Loc *Result = dyn_cast<Loc>(&ResultVal)) |
| return evalCastFromLoc(*Result, resultTy); |
| else |
| 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(isa<loc::MemRegionVal>(rhs) || isa<loc::GotoLabel>(rhs)); |
| 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 (loc::ConcreteInt *rInt = dyn_cast<loc::ConcreteInt>(&rhs)) { |
| // 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()) |
| 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()) { |
| switch (op) { |
| default: |
| break; |
| case BO_Sub: |
| return evalCastFromLoc(lhs, resultTy); |
| case BO_EQ: |
| case BO_LT: |
| case BO_LE: |
| return makeTruthVal(false, resultTy); |
| case BO_NE: |
| case BO_GT: |
| case BO_GE: |
| return makeTruthVal(true, 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(); |
| |
| // If both values wrap regions, see if they're from different base regions. |
| const MemRegion *LeftBase = LeftMR->getBaseRegion(); |
| const MemRegion *RightBase = RightMR->getBaseRegion(); |
| if (LeftBase != RightBase && |
| !isa<SymbolicRegion>(LeftBase) && !isa<SymbolicRegion>(RightBase)) { |
| switch (op) { |
| default: |
| return UnknownVal(); |
| case BO_EQ: |
| return makeTruthVal(false, resultTy); |
| case BO_NE: |
| return makeTruthVal(true, resultTy); |
| } |
| } |
| |
| // The two regions are from the same base region. See if they're both a |
| // type of region we know how to compare. |
| const MemSpaceRegion *LeftMS = LeftBase->getMemorySpace(); |
| const MemSpaceRegion *RightMS = RightBase->getMemorySpace(); |
| |
| // Heuristic: assume that no symbolic region (whose memory space is |
| // unknown) is on the stack. |
| // FIXME: we should be able to be more precise once we can do better |
| // aliasing constraints for symbolic regions, but this is a reasonable, |
| // albeit unsound, assumption that holds most of the time. |
| if (isa<StackSpaceRegion>(LeftMS) ^ isa<StackSpaceRegion>(RightMS)) { |
| switch (op) { |
| default: |
| break; |
| case BO_EQ: |
| return makeTruthVal(false, resultTy); |
| case BO_NE: |
| return makeTruthVal(true, resultTy); |
| } |
| } |
| |
| // FIXME: If/when there is a getAsRawOffset() for FieldRegions, this |
| // ElementRegion path and the FieldRegion path below should be unified. |
| if (const ElementRegion *LeftER = dyn_cast<ElementRegion>(LeftMR)) { |
| // First see if the right region is also an ElementRegion. |
| const ElementRegion *RightER = dyn_cast<ElementRegion>(RightMR); |
| if (!RightER) |
| return UnknownVal(); |
| |
| // 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(); |
| NonLoc *LeftIndex = dyn_cast<NonLoc>(&LeftIndexVal); |
| if (!LeftIndex) |
| return UnknownVal(); |
| LeftIndexVal = evalCastFromNonLoc(*LeftIndex, resultTy); |
| LeftIndex = dyn_cast<NonLoc>(&LeftIndexVal); |
| if (!LeftIndex) |
| return UnknownVal(); |
| |
| // Do the same for the right index. |
| SVal RightIndexVal = RightER->getIndex(); |
| NonLoc *RightIndex = dyn_cast<NonLoc>(&RightIndexVal); |
| if (!RightIndex) |
| return UnknownVal(); |
| RightIndexVal = evalCastFromNonLoc(*RightIndex, resultTy); |
| RightIndex = dyn_cast<NonLoc>(&RightIndexVal); |
| 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); |
| } |
| |
| // If the element indexes aren't comparable, see if the raw offsets are. |
| RegionRawOffset LeftOffset = LeftER->getAsArrayOffset(); |
| RegionRawOffset RightOffset = RightER->getAsArrayOffset(); |
| |
| if (LeftOffset.getRegion() != NULL && |
| LeftOffset.getRegion() == RightOffset.getRegion()) { |
| CharUnits left = LeftOffset.getOffset(); |
| CharUnits 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); |
| } |
| } |
| |
| // If we get here, we have no way of comparing the ElementRegions. |
| return UnknownVal(); |
| } |
| |
| // See if both regions are fields of the same structure. |
| // FIXME: This doesn't handle nesting, inheritance, or Objective-C ivars. |
| if (const FieldRegion *LeftFR = dyn_cast<FieldRegion>(LeftMR)) { |
| // Only comparisons are meaningful here! |
| if (!BinaryOperator::isComparisonOp(op)) |
| return UnknownVal(); |
| |
| // First see if the right region is also a FieldRegion. |
| const FieldRegion *RightFR = dyn_cast<FieldRegion>(RightMR); |
| if (!RightFR) |
| 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 makeTruthVal(false, resultTy); |
| if (op == BO_NE) |
| return 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 (RecordDecl::field_iterator I = RD->field_begin(), |
| E = RD->field_end(); I!=E; ++I) { |
| if (*I == LeftFD) |
| return makeTruthVal(leftFirst, resultTy); |
| if (*I == RightFD) |
| return makeTruthVal(!leftFirst, resultTy); |
| } |
| |
| llvm_unreachable("Fields not found in parent record's definition"); |
| } |
| |
| // 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) { |
| |
| // Special case: rhs is a zero constant. |
| if (rhs.isZeroConstant()) |
| return lhs; |
| |
| // Special case: 'rhs' is an integer that has the same width as a pointer and |
| // we are using the integer location in a comparison. Normally this cannot be |
| // triggered, but transfer functions like those for OSCommpareAndSwapBarrier32 |
| // can generate comparisons that trigger this code. |
| // FIXME: Are all locations guaranteed to have pointer width? |
| if (BinaryOperator::isComparisonOp(op)) { |
| if (nonloc::ConcreteInt *rhsInt = dyn_cast<nonloc::ConcreteInt>(&rhs)) { |
| const llvm::APSInt *x = &rhsInt->getValue(); |
| ASTContext &ctx = Context; |
| if (ctx.getTypeSize(ctx.VoidPtrTy) == x->getBitWidth()) { |
| // Convert the signedness of the integer (if necessary). |
| if (x->isSigned()) |
| x = &getBasicValueFactory().getValue(*x, true); |
| |
| return evalBinOpLL(state, op, lhs, loc::ConcreteInt(*x), resultTy); |
| } |
| } |
| return UnknownVal(); |
| } |
| |
| // We are dealing with pointer arithmetic. |
| |
| // Handle pointer arithmetic on constant values. |
| if (nonloc::ConcreteInt *rhsInt = dyn_cast<nonloc::ConcreteInt>(&rhs)) { |
| if (loc::ConcreteInt *lhsInt = dyn_cast<loc::ConcreteInt>(&lhs)) { |
| 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 = cast<NonLoc>(convertToArrayIndex(rhs)); |
| SVal index = UnknownVal(); |
| const MemRegion *superR = 0; |
| 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 (const PointerType *PT = resultTy->getAs<PointerType>()) { |
| elementType = PT->getPointeeType(); |
| } |
| else { |
| const ObjCObjectPointerType *OT = |
| resultTy->getAs<ObjCObjectPointerType>(); |
| elementType = OT->getPointeeType(); |
| } |
| } |
| |
| if (NonLoc *indexV = dyn_cast<NonLoc>(&index)) { |
| return loc::MemRegionVal(MemMgr.getElementRegion(elementType, *indexV, |
| superR, getContext())); |
| } |
| } |
| return UnknownVal(); |
| } |
| |
| const llvm::APSInt *SimpleSValBuilder::getKnownValue(ProgramStateRef state, |
| SVal V) { |
| if (V.isUnknownOrUndef()) |
| return NULL; |
| |
| if (loc::ConcreteInt* X = dyn_cast<loc::ConcreteInt>(&V)) |
| return &X->getValue(); |
| |
| if (nonloc::ConcreteInt* X = dyn_cast<nonloc::ConcreteInt>(&V)) |
| return &X->getValue(); |
| |
| if (SymbolRef Sym = V.getAsSymbol()) |
| return state->getSymVal(Sym); |
| |
| // FIXME: Add support for SymExprs. |
| return NULL; |
| } |
