const GRState*
SimpleConstraintManager::AssumeInBound(const GRState* St, SVal Idx,
SVal UpperBound, bool Assumption,
bool& isFeasible) {
// Only support ConcreteInt for now.
if (!(isa<nonloc::ConcreteInt>(Idx) && isa<nonloc::ConcreteInt>(UpperBound))){
isFeasible = true;
return St;
}
const llvm::APSInt& Zero = getBasicVals().getZeroWithPtrWidth(false);
llvm::APSInt IdxV = cast<nonloc::ConcreteInt>(Idx).getValue();
// IdxV might be too narrow.
if (IdxV.getBitWidth() < Zero.getBitWidth())
IdxV.extend(Zero.getBitWidth());
// UBV might be too narrow, too.
llvm::APSInt UBV = cast<nonloc::ConcreteInt>(UpperBound).getValue();
if (UBV.getBitWidth() < Zero.getBitWidth())
UBV.extend(Zero.getBitWidth());
bool InBound = (Zero <= IdxV) && (IdxV < UBV);
isFeasible = Assumption ? InBound : !InBound;
return St;
}
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
}
ProgramStateRef RangedConstraintManager::assumeSym(ProgramStateRef State,
SymbolRef Sym,
bool Assumption) {
// Handle SymbolData.
if (isa<SymbolData>(Sym)) {
return assumeSymUnsupported(State, Sym, Assumption);
// Handle symbolic expression.
} else if (const SymIntExpr *SIE = dyn_cast<SymIntExpr>(Sym)) {
// We can only simplify expressions whose RHS is an integer.
BinaryOperator::Opcode op = SIE->getOpcode();
if (BinaryOperator::isComparisonOp(op) && op != BO_Cmp) {
if (!Assumption)
op = BinaryOperator::negateComparisonOp(op);
return assumeSymRel(State, SIE->getLHS(), op, SIE->getRHS());
}
} else if (const SymSymExpr *SSE = dyn_cast<SymSymExpr>(Sym)) {
// Translate "a != b" to "(b - a) != 0".
// We invert the order of the operands as a heuristic for how loop
// conditions are usually written ("begin != end") as compared to length
// calculations ("end - begin"). The more correct thing to do would be to
// canonicalize "a - b" and "b - a", which would allow us to treat
// "a != b" and "b != a" the same.
SymbolManager &SymMgr = getSymbolManager();
BinaryOperator::Opcode Op = SSE->getOpcode();
assert(BinaryOperator::isComparisonOp(Op));
// For now, we only support comparing pointers.
if (Loc::isLocType(SSE->getLHS()->getType()) &&
Loc::isLocType(SSE->getRHS()->getType())) {
QualType DiffTy = SymMgr.getContext().getPointerDiffType();
SymbolRef Subtraction =
SymMgr.getSymSymExpr(SSE->getRHS(), BO_Sub, SSE->getLHS(), DiffTy);
const llvm::APSInt &Zero = getBasicVals().getValue(0, DiffTy);
Op = BinaryOperator::reverseComparisonOp(Op);
if (!Assumption)
Op = BinaryOperator::negateComparisonOp(Op);
return assumeSymRel(State, Subtraction, Op, Zero);
}
}
// If we get here, there's nothing else we can do but treat the symbol as
// opaque.
return assumeSymUnsupported(State, Sym, Assumption);
}
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);
}
ProgramStateRef SimpleConstraintManager::assumeAux(ProgramStateRef state,
Loc Cond, bool Assumption) {
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 = getBasicVals().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
}
ProgramStateRef SimpleConstraintManager::assumeAux(ProgramStateRef State,
NonLoc Cond,
bool Assumption) {
// We cannot reason about SymSymExprs, and can only reason about some
// SymIntExprs.
if (!canReasonAbout(Cond)) {
// Just add the constraint to the expression without trying to simplify.
SymbolRef Sym = Cond.getAsSymExpr();
return assumeAuxForSymbol(State, Sym, Assumption);
}
switch (Cond.getSubKind()) {
default:
llvm_unreachable("'Assume' not implemented for this NonLoc");
case nonloc::SymbolValKind: {
nonloc::SymbolVal SV = Cond.castAs<nonloc::SymbolVal>();
SymbolRef Sym = SV.getSymbol();
assert(Sym);
// Handle SymbolData.
if (!SV.isExpression()) {
return assumeAuxForSymbol(State, Sym, Assumption);
// Handle symbolic expression.
} else if (const SymIntExpr *SE = dyn_cast<SymIntExpr>(Sym)) {
// We can only simplify expressions whose RHS is an integer.
BinaryOperator::Opcode Op = SE->getOpcode();
if (BinaryOperator::isComparisonOp(Op)) {
if (!Assumption)
Op = BinaryOperator::negateComparisonOp(Op);
return assumeSymRel(State, SE->getLHS(), Op, SE->getRHS());
}
} else if (const SymSymExpr *SSE = dyn_cast<SymSymExpr>(Sym)) {
// Translate "a != b" to "(b - a) != 0".
// We invert the order of the operands as a heuristic for how loop
// conditions are usually written ("begin != end") as compared to length
// calculations ("end - begin"). The more correct thing to do would be to
// canonicalize "a - b" and "b - a", which would allow us to treat
// "a != b" and "b != a" the same.
SymbolManager &SymMgr = getSymbolManager();
BinaryOperator::Opcode Op = SSE->getOpcode();
assert(BinaryOperator::isComparisonOp(Op));
// For now, we only support comparing pointers.
assert(Loc::isLocType(SSE->getLHS()->getType()));
assert(Loc::isLocType(SSE->getRHS()->getType()));
QualType DiffTy = SymMgr.getContext().getPointerDiffType();
SymbolRef Subtraction =
SymMgr.getSymSymExpr(SSE->getRHS(), BO_Sub, SSE->getLHS(), DiffTy);
const llvm::APSInt &Zero = getBasicVals().getValue(0, DiffTy);
Op = BinaryOperator::reverseComparisonOp(Op);
if (!Assumption)
Op = BinaryOperator::negateComparisonOp(Op);
return assumeSymRel(State, Subtraction, Op, Zero);
}
// If we get here, there's nothing else we can do but treat the symbol as
// opaque.
return assumeAuxForSymbol(State, Sym, Assumption);
}
case nonloc::ConcreteIntKind: {
bool b = Cond.castAs<nonloc::ConcreteInt>().getValue() != 0;
bool isFeasible = b ? Assumption : !Assumption;
return isFeasible ? State : nullptr;
}
case nonloc::PointerToMemberKind: {
bool IsNull = !Cond.castAs<nonloc::PointerToMember>().isNullMemberPointer();
bool IsFeasible = IsNull ? Assumption : !Assumption;
return IsFeasible ? State : nullptr;
}
case nonloc::LocAsIntegerKind:
return assume(State, Cond.castAs<nonloc::LocAsInteger>().getLoc(),
Assumption);
} // end switch
}
ProgramStateRef SimpleConstraintManager::assumeAux(ProgramStateRef state,
NonLoc Cond,
bool Assumption) {
// We cannot reason about SymSymExprs, and can only reason about some
// SymIntExprs.
if (!canReasonAbout(Cond)) {
// Just add the constraint to the expression without trying to simplify.
SymbolRef sym = Cond.getAsSymExpr();
return assumeAuxForSymbol(state, sym, Assumption);
}
BasicValueFactory &BasicVals = getBasicVals();
switch (Cond.getSubKind()) {
default:
llvm_unreachable("'Assume' not implemented for this NonLoc");
case nonloc::SymbolValKind: {
nonloc::SymbolVal& SV = cast<nonloc::SymbolVal>(Cond);
SymbolRef sym = SV.getSymbol();
assert(sym);
// Handle SymbolData.
if (!SV.isExpression()) {
return assumeAuxForSymbol(state, sym, Assumption);
// Handle symbolic expression.
} else {
// We can only simplify expressions whose RHS is an integer.
const SymIntExpr *SE = dyn_cast<SymIntExpr>(sym);
if (!SE)
return assumeAuxForSymbol(state, sym, Assumption);
BinaryOperator::Opcode op = SE->getOpcode();
// Implicitly compare non-comparison expressions to 0.
if (!BinaryOperator::isComparisonOp(op)) {
QualType T = SE->getType(BasicVals.getContext());
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
}
