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
}
ProgramStateRef
SimpleConstraintManager::assumeAuxForSymbol(ProgramStateRef State,
SymbolRef Sym, bool Assumption) {
BasicValueFactory &BVF = getBasicVals();
QualType T = Sym->getType();
// None of the constraint solvers currently support non-integer types.
if (!T->isIntegralOrEnumerationType())
return State;
const llvm::APSInt &zero = BVF.getValue(0, T);
if (Assumption)
return assumeSymNE(State, Sym, zero, zero);
else
return assumeSymEQ(State, Sym, zero, zero);
}
ProgramStateRef
RangedConstraintManager::assumeSymUnsupported(ProgramStateRef State,
SymbolRef Sym, bool Assumption) {
BasicValueFactory &BVF = getBasicVals();
QualType T = Sym->getType();
// Non-integer types are not supported.
if (!T->isIntegralOrEnumerationType())
return State;
// Reverse the operation and add directly to state.
const llvm::APSInt &Zero = BVF.getValue(0, T);
if (Assumption)
return assumeSymNE(State, Sym, Zero, Zero);
else
return assumeSymEQ(State, Sym, Zero, Zero);
}
const ProgramState *SimpleConstraintManager::assumeAux(const ProgramState *state,
Loc Cond, bool Assumption) {
BasicValueFactory &BasicVals = state->getBasicVals();
switch (Cond.getSubKind()) {
default:
assert (false && "'Assume' not implemented for this Loc.");
return state;
case loc::MemRegionKind: {
// FIXME: Should this go into the storemanager?
const MemRegion *R = cast<loc::MemRegionVal>(Cond).getRegion();
const SubRegion *SubR = dyn_cast<SubRegion>(R);
while (SubR) {
// FIXME: now we only find the first symbolic region.
if (const SymbolicRegion *SymR = dyn_cast<SymbolicRegion>(SubR)) {
const llvm::APSInt &zero = BasicVals.getZeroWithPtrWidth();
if (Assumption)
return assumeSymNE(state, SymR->getSymbol(), zero, zero);
else
return assumeSymEQ(state, SymR->getSymbol(), zero, zero);
}
SubR = dyn_cast<SubRegion>(SubR->getSuperRegion());
}
// FALL-THROUGH.
}
case loc::GotoLabelKind:
return Assumption ? state : NULL;
case loc::ConcreteIntKind: {
bool b = cast<loc::ConcreteInt>(Cond).getValue() != 0;
bool isFeasible = b ? Assumption : !Assumption;
return isFeasible ? state : NULL;
}
} // end switch
}
const ProgramState *SimpleConstraintManager::assumeSymRel(const ProgramState *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.");
// 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.
llvm::APSInt Adjustment;
// First check if the LHS is a simple symbol reference.
SymbolRef Sym = dyn_cast<SymbolData>(LHS);
if (Sym) {
Adjustment = 0;
} else {
// Next, see if it's a "($sym+constant1)" expression.
const SymIntExpr *SE = dyn_cast<SymIntExpr>(LHS);
// We don't handle "($sym1+$sym2)".
// Give up and assume the constraint is feasible.
if (!SE)
return state;
// We don't handle "(<expr>+constant1)".
// Give up and assume the constraint is feasible.
Sym = dyn_cast<SymbolData>(SE->getLHS());
if (!Sym)
return state;
// Get the constant out of the expression "($sym+constant1)".
switch (SE->getOpcode()) {
case BO_Add:
Adjustment = SE->getRHS();
break;
case BO_Sub:
Adjustment = -SE->getRHS();
break;
default:
// We don't handle non-additive operators.
// Give up and assume the constraint is feasible.
return state;
}
}
// FIXME: This next section is a hack. It silently converts the integers to
// be of the same type as the symbol, which is not always correct. Really the
// comparisons should be performed using the Int's type, then mapped back to
// the symbol's range of values.
ProgramStateManager &StateMgr = state->getStateManager();
ASTContext &Ctx = StateMgr.getContext();
QualType T = Sym->getType(Ctx);
assert(T->isIntegerType() || Loc::isLocType(T));
unsigned bitwidth = Ctx.getTypeSize(T);
bool isSymUnsigned
= T->isUnsignedIntegerOrEnumerationType() || Loc::isLocType(T);
// Convert the adjustment.
Adjustment.setIsUnsigned(isSymUnsigned);
Adjustment = Adjustment.extOrTrunc(bitwidth);
// Convert the right-hand side integer.
llvm::APSInt ConvertedInt(Int, isSymUnsigned);
ConvertedInt = ConvertedInt.extOrTrunc(bitwidth);
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
}
const ProgramState *SimpleConstraintManager::assumeAux(const ProgramState *state,
NonLoc Cond,
bool Assumption) {
// We cannot reason about SymSymExprs,
// and can only reason about some SymIntExprs.
if (!canReasonAbout(Cond)) {
// Just return the current state indicating that the path is feasible.
// This may be an over-approximation of what is possible.
return state;
}
BasicValueFactory &BasicVals = state->getBasicVals();
SymbolManager &SymMgr = state->getSymbolManager();
switch (Cond.getSubKind()) {
default:
assert(false && "'Assume' not implemented for this NonLoc");
case nonloc::SymbolValKind: {
nonloc::SymbolVal& SV = cast<nonloc::SymbolVal>(Cond);
SymbolRef sym = SV.getSymbol();
QualType T = SymMgr.getType(sym);
const llvm::APSInt &zero = BasicVals.getValue(0, T);
if (Assumption)
return assumeSymNE(state, sym, zero, zero);
else
return assumeSymEQ(state, sym, zero, zero);
}
case nonloc::SymExprValKind: {
nonloc::SymExprVal V = cast<nonloc::SymExprVal>(Cond);
// For now, we only handle expressions whose RHS is an integer.
// All other expressions are assumed to be feasible.
const SymIntExpr *SE = dyn_cast<SymIntExpr>(V.getSymbolicExpression());
if (!SE)
return state;
BinaryOperator::Opcode op = SE->getOpcode();
// Implicitly compare non-comparison expressions to 0.
if (!BinaryOperator::isComparisonOp(op)) {
QualType T = SymMgr.getType(SE);
const llvm::APSInt &zero = BasicVals.getValue(0, T);
op = (Assumption ? BO_NE : BO_EQ);
return assumeSymRel(state, SE, op, zero);
}
// From here on out, op is the real comparison we'll be testing.
if (!Assumption)
op = NegateComparison(op);
return assumeSymRel(state, SE->getLHS(), op, SE->getRHS());
}
case nonloc::ConcreteIntKind: {
bool b = cast<nonloc::ConcreteInt>(Cond).getValue() != 0;
bool isFeasible = b ? Assumption : !Assumption;
return isFeasible ? state : NULL;
}
case nonloc::LocAsIntegerKind:
return assumeAux(state, cast<nonloc::LocAsInteger>(Cond).getLoc(),
Assumption);
} // end switch
}
