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::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
}
