ProgramStateRef SimpleConstraintManager::assumeSymWithinInclusiveRange(
ProgramStateRef State, SymbolRef Sym, const llvm::APSInt &From,
const llvm::APSInt &To, bool InRange) {
// Get the type used for calculating wraparound.
BasicValueFactory &BVF = getBasicVals();
APSIntType WraparoundType = BVF.getAPSIntType(Sym->getType());
llvm::APSInt Adjustment = WraparoundType.getZeroValue();
SymbolRef AdjustedSym = Sym;
computeAdjustment(AdjustedSym, Adjustment);
// Convert the right-hand side integer as necessary.
APSIntType ComparisonType = std::max(WraparoundType, APSIntType(From));
llvm::APSInt ConvertedFrom = ComparisonType.convert(From);
llvm::APSInt ConvertedTo = ComparisonType.convert(To);
// Prefer unsigned comparisons.
if (ComparisonType.getBitWidth() == WraparoundType.getBitWidth() &&
ComparisonType.isUnsigned() && !WraparoundType.isUnsigned())
Adjustment.setIsSigned(false);
if (InRange)
return assumeSymbolWithinInclusiveRange(State, AdjustedSym, ConvertedFrom,
ConvertedTo, Adjustment);
return assumeSymbolOutOfInclusiveRange(State, AdjustedSym, ConvertedFrom,
ConvertedTo, Adjustment);
}
ProgramStateRef SimpleConstraintManager::assumeSymRel(ProgramStateRef State,
const SymExpr *LHS,
BinaryOperator::Opcode Op,
const llvm::APSInt &Int) {
assert(BinaryOperator::isComparisonOp(Op) &&
"Non-comparison ops should be rewritten as comparisons to zero.");
// Get the type used for calculating wraparound.
BasicValueFactory &BVF = getBasicVals();
APSIntType WraparoundType = BVF.getAPSIntType(LHS->getType());
// We only handle simple comparisons of the form "$sym == constant"
// or "($sym+constant1) == constant2".
// The adjustment is "constant1" in the above expression. It's used to
// "slide" the solution range around for modular arithmetic. For example,
// x < 4 has the solution [0, 3]. x+2 < 4 has the solution [0-2, 3-2], which
// in modular arithmetic is [0, 1] U [UINT_MAX-1, UINT_MAX]. It's up to
// the subclasses of SimpleConstraintManager to handle the adjustment.
SymbolRef Sym = LHS;
llvm::APSInt Adjustment = WraparoundType.getZeroValue();
computeAdjustment(Sym, Adjustment);
// Convert the right-hand side integer as necessary.
APSIntType ComparisonType = std::max(WraparoundType, APSIntType(Int));
llvm::APSInt ConvertedInt = ComparisonType.convert(Int);
// Prefer unsigned comparisons.
if (ComparisonType.getBitWidth() == WraparoundType.getBitWidth() &&
ComparisonType.isUnsigned() && !WraparoundType.isUnsigned())
Adjustment.setIsSigned(false);
switch (Op) {
default:
llvm_unreachable("invalid operation not caught by assertion above");
case BO_EQ:
return assumeSymEQ(State, Sym, ConvertedInt, Adjustment);
case BO_NE:
return assumeSymNE(State, Sym, ConvertedInt, Adjustment);
case BO_GT:
return assumeSymGT(State, Sym, ConvertedInt, Adjustment);
case BO_GE:
return assumeSymGE(State, Sym, ConvertedInt, Adjustment);
case BO_LT:
return assumeSymLT(State, Sym, ConvertedInt, Adjustment);
case BO_LE:
return assumeSymLE(State, Sym, ConvertedInt, Adjustment);
} // end switch
}
ProgramStateRef SimpleConstraintManager::assumeSymRel(ProgramStateRef state,
const SymExpr *LHS,
BinaryOperator::Opcode op,
const llvm::APSInt& Int) {
assert(BinaryOperator::isComparisonOp(op) &&
"Non-comparison ops should be rewritten as comparisons to zero.");
BasicValueFactory &BVF = getBasicVals();
ASTContext &Ctx = BVF.getContext();
// Get the type used for calculating wraparound.
APSIntType WraparoundType = BVF.getAPSIntType(LHS->getType(Ctx));
// We only handle simple comparisons of the form "$sym == constant"
// or "($sym+constant1) == constant2".
// The adjustment is "constant1" in the above expression. It's used to
// "slide" the solution range around for modular arithmetic. For example,
// x < 4 has the solution [0, 3]. x+2 < 4 has the solution [0-2, 3-2], which
// in modular arithmetic is [0, 1] U [UINT_MAX-1, UINT_MAX]. It's up to
// the subclasses of SimpleConstraintManager to handle the adjustment.
SymbolRef Sym = LHS;
llvm::APSInt Adjustment = WraparoundType.getZeroValue();
computeAdjustment(Sym, Adjustment);
// Convert the right-hand side integer as necessary.
APSIntType ComparisonType = std::max(WraparoundType, APSIntType(Int));
llvm::APSInt ConvertedInt = ComparisonType.convert(Int);
switch (op) {
default:
// No logic yet for other operators. assume the constraint is feasible.
return state;
case BO_EQ:
return assumeSymEQ(state, Sym, ConvertedInt, Adjustment);
case BO_NE:
return assumeSymNE(state, Sym, ConvertedInt, Adjustment);
case BO_GT:
return assumeSymGT(state, Sym, ConvertedInt, Adjustment);
case BO_GE:
return assumeSymGE(state, Sym, ConvertedInt, Adjustment);
case BO_LT:
return assumeSymLT(state, Sym, ConvertedInt, Adjustment);
case BO_LE:
return assumeSymLE(state, Sym, ConvertedInt, Adjustment);
} // end switch
}
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::PointerToMemberKind: {
assert(rhs.getSubKind() == nonloc::PointerToMemberKind &&
"Both SVals should have pointer-to-member-type");
auto LPTM = lhs.castAs<nonloc::PointerToMember>(),
RPTM = rhs.castAs<nonloc::PointerToMember>();
auto LPTMD = LPTM.getPTMData(), RPTMD = RPTM.getPTMData();
switch (op) {
case BO_EQ:
return makeTruthVal(LPTMD == RPTMD, resultTy);
case BO_NE:
return makeTruthVal(LPTMD != RPTMD, resultTy);
default:
return UnknownVal();
}
}
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.
// FIXME: This only makes sense for comparisons. If we want to, say,
// add 1 to a LocAsInteger, we'd better unpack the Loc and add to it,
// then pack it back into a LocAsInteger.
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);
}
}
}
}