FlatStoreManager::RegionInterval
FlatStoreManager::RegionToInterval(const MemRegion *R) {
switch (R->getKind()) {
case MemRegion::VarRegionKind: {
QualType T = cast<VarRegion>(R)->getValueType();
int64_t Size = Ctx.getTypeSize(T);
return RegionInterval(R, 0, Size-1);
}
case MemRegion::ElementRegionKind:
case MemRegion::FieldRegionKind: {
RegionOffset Offset = R->getAsOffset();
// We cannot compute offset for all regions, for example, elements
// with symbolic offsets.
if (!Offset.getRegion())
return RegionInterval(0, 0, 0);
int64_t Start = Offset.getOffset();
int64_t Size = Ctx.getTypeSize(cast<TypedRegion>(R)->getValueType());
return RegionInterval(Offset.getRegion(), Start, Start+Size);
}
default:
llvm_unreachable("Region kind unhandled.");
return RegionInterval(0, 0, 0);
}
}
// 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 = lhs.castAs<loc::ConcreteInt>().getValue();
op = BinaryOperator::reverseComparisonOp(op);
return makeNonLoc(rSym, op, lVal, resultTy);
}
// If both operands are constants, just perform the operation.
if (Optional<loc::ConcreteInt> rInt = rhs.getAs<loc::ConcreteInt>()) {
SVal ResultVal =
lhs.castAs<loc::ConcreteInt>().evalBinOp(BasicVals, op, *rInt);
if (Optional<NonLoc> Result = ResultVal.getAs<NonLoc>())
return evalCastFromNonLoc(*Result, resultTy);
assert(!ResultVal.getAs<Loc>() && "Loc-Loc ops should not produce Locs");
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(rhs.getAs<loc::MemRegionVal>() || rhs.getAs<loc::GotoLabel>());
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::MemRegionValKind: {
if (Optional<loc::ConcreteInt> rInt = rhs.getAs<loc::ConcreteInt>()) {
// 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(true))
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()) {
if (op == BO_Sub)
return evalCastFromLoc(lhs, resultTy);
if (BinaryOperator::isComparisonOp(op)) {
QualType boolType = getContext().BoolTy;
NonLoc l = evalCastFromLoc(lhs, boolType).castAs<NonLoc>();
NonLoc r = makeTruthVal(false, boolType).castAs<NonLoc>();
return evalBinOpNN(state, op, l, r, 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 && "MemRegionValKind 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();
const MemRegion *LeftBase = LeftMR->getBaseRegion();
const MemRegion *RightBase = RightMR->getBaseRegion();
const MemSpaceRegion *LeftMS = LeftBase->getMemorySpace();
const MemSpaceRegion *RightMS = RightBase->getMemorySpace();
const MemSpaceRegion *UnknownMS = MemMgr.getUnknownRegion();
// If the two regions are from different known memory spaces they cannot be
// equal. Also, assume that no symbolic region (whose memory space is
// unknown) is on the stack.
if (LeftMS != RightMS &&
((LeftMS != UnknownMS && RightMS != UnknownMS) ||
(isa<StackSpaceRegion>(LeftMS) || isa<StackSpaceRegion>(RightMS)))) {
switch (op) {
default:
return UnknownVal();
case BO_EQ:
return makeTruthVal(false, resultTy);
case BO_NE:
return makeTruthVal(true, resultTy);
}
}
// If both values wrap regions, see if they're from different base regions.
// Note, heap base symbolic regions are assumed to not alias with
// each other; for example, we assume that malloc returns different address
// on each invocation.
// FIXME: ObjC object pointers always reside on the heap, but currently
// we treat their memory space as unknown, because symbolic pointers
// to ObjC objects may alias. There should be a way to construct
// possibly-aliasing heap-based regions. For instance, MacOSXApiChecker
// guesses memory space for ObjC object pointers manually instead of
// relying on us.
if (LeftBase != RightBase &&
((!isa<SymbolicRegion>(LeftBase) && !isa<SymbolicRegion>(RightBase)) ||
(isa<HeapSpaceRegion>(LeftMS) || isa<HeapSpaceRegion>(RightMS))) ){
switch (op) {
default:
return UnknownVal();
case BO_EQ:
return makeTruthVal(false, resultTy);
case BO_NE:
return makeTruthVal(true, resultTy);
}
}
// Handle special cases for when both regions are element regions.
const ElementRegion *RightER = dyn_cast<ElementRegion>(RightMR);
const ElementRegion *LeftER = dyn_cast<ElementRegion>(LeftMR);
if (RightER && LeftER) {
// 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();
Optional<NonLoc> LeftIndex = LeftIndexVal.getAs<NonLoc>();
if (!LeftIndex)
return UnknownVal();
LeftIndexVal = evalCastFromNonLoc(*LeftIndex, ArrayIndexTy);
LeftIndex = LeftIndexVal.getAs<NonLoc>();
if (!LeftIndex)
return UnknownVal();
// Do the same for the right index.
SVal RightIndexVal = RightER->getIndex();
Optional<NonLoc> RightIndex = RightIndexVal.getAs<NonLoc>();
if (!RightIndex)
return UnknownVal();
RightIndexVal = evalCastFromNonLoc(*RightIndex, ArrayIndexTy);
RightIndex = RightIndexVal.getAs<NonLoc>();
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);
}
}
// Special handling of the FieldRegions, even with symbolic offsets.
const FieldRegion *RightFR = dyn_cast<FieldRegion>(RightMR);
const FieldRegion *LeftFR = dyn_cast<FieldRegion>(LeftMR);
if (RightFR && LeftFR) {
SVal R = evalBinOpFieldRegionFieldRegion(LeftFR, RightFR, op, resultTy,
*this);
if (!R.isUnknown())
return R;
}
// Compare the regions using the raw offsets.
RegionOffset LeftOffset = LeftMR->getAsOffset();
RegionOffset RightOffset = RightMR->getAsOffset();
if (LeftOffset.getRegion() != nullptr &&
LeftOffset.getRegion() == RightOffset.getRegion() &&
!LeftOffset.hasSymbolicOffset() && !RightOffset.hasSymbolicOffset()) {
int64_t left = LeftOffset.getOffset();
int64_t 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);
}
}
// At this point we're not going to get a good answer, but we can try
// conjuring an expression instead.
SymbolRef LHSSym = lhs.getAsLocSymbol();
SymbolRef RHSSym = rhs.getAsLocSymbol();
if (LHSSym && RHSSym)
return makeNonLoc(LHSSym, op, RHSSym, resultTy);
// If we get here, we have no way of comparing the regions.
return UnknownVal();
}
}
}
