[analyzer][UninitializedObjectChecker] Fixed dereferencing
iThis patch aims to fix derefencing, which has been debated for months now.
Instead of working with SVals, the function now relies on TypedValueRegion.
Differential Revision: https://reviews.llvm.org/D51057
llvm-svn: 342213
diff --git a/clang/lib/StaticAnalyzer/Checkers/UninitializedObject/UninitializedPointee.cpp b/clang/lib/StaticAnalyzer/Checkers/UninitializedObject/UninitializedPointee.cpp
index 72e256b..22e3cbd 100644
--- a/clang/lib/StaticAnalyzer/Checkers/UninitializedObject/UninitializedPointee.cpp
+++ b/clang/lib/StaticAnalyzer/Checkers/UninitializedObject/UninitializedPointee.cpp
@@ -95,11 +95,13 @@
/// known, and thus FD can not be analyzed.
static bool isVoidPointer(QualType T);
-/// Dereferences \p V and returns the value and dynamic type of the pointee, as
-/// well as whether \p FR needs to be casted back to that type. If for whatever
-/// reason dereferencing fails, returns with None.
-static llvm::Optional<std::tuple<SVal, QualType, bool>>
-dereference(ProgramStateRef State, const FieldRegion *FR);
+using DereferenceInfo = std::pair<const TypedValueRegion *, bool>;
+
+/// Dereferences \p FR and returns with the pointee's region, and whether it
+/// needs to be casted back to it's location type. If for whatever reason
+/// dereferencing fails, returns with None.
+static llvm::Optional<DereferenceInfo> dereference(ProgramStateRef State,
+ const FieldRegion *FR);
//===----------------------------------------------------------------------===//
// Methods for FindUninitializedFields.
@@ -110,10 +112,8 @@
bool FindUninitializedFields::isPointerOrReferenceUninit(
const FieldRegion *FR, FieldChainInfo LocalChain) {
- assert((FR->getDecl()->getType()->isAnyPointerType() ||
- FR->getDecl()->getType()->isReferenceType() ||
- FR->getDecl()->getType()->isBlockPointerType()) &&
- "This method only checks pointer/reference objects!");
+ assert(isDereferencableType(FR->getDecl()->getType()) &&
+ "This method only checks dereferencable objects!");
SVal V = State->getSVal(FR);
@@ -134,54 +134,47 @@
// At this point the pointer itself is initialized and points to a valid
// location, we'll now check the pointee.
- llvm::Optional<std::tuple<SVal, QualType, bool>> DerefInfo =
- dereference(State, FR);
+ llvm::Optional<DereferenceInfo> DerefInfo = dereference(State, FR);
if (!DerefInfo) {
IsAnyFieldInitialized = true;
return false;
}
- V = std::get<0>(*DerefInfo);
- QualType DynT = std::get<1>(*DerefInfo);
- bool NeedsCastBack = std::get<2>(*DerefInfo);
+ const TypedValueRegion *R = DerefInfo->first;
+ const bool NeedsCastBack = DerefInfo->second;
- // If FR is a pointer pointing to a non-primitive type.
- if (Optional<nonloc::LazyCompoundVal> RecordV =
- V.getAs<nonloc::LazyCompoundVal>()) {
+ QualType DynT = R->getLocationType();
+ QualType PointeeT = DynT->getPointeeType();
- const TypedValueRegion *R = RecordV->getRegion();
+ if (PointeeT->isStructureOrClassType()) {
+ if (NeedsCastBack)
+ return isNonUnionUninit(R, LocalChain.add(NeedsCastLocField(FR, DynT)));
+ return isNonUnionUninit(R, LocalChain.add(LocField(FR)));
+ }
- if (DynT->getPointeeType()->isStructureOrClassType()) {
+ if (PointeeT->isUnionType()) {
+ if (isUnionUninit(R)) {
if (NeedsCastBack)
- return isNonUnionUninit(R, LocalChain.add(NeedsCastLocField(FR, DynT)));
- return isNonUnionUninit(R, LocalChain.add(LocField(FR)));
- }
-
- if (DynT->getPointeeType()->isUnionType()) {
- if (isUnionUninit(R)) {
- if (NeedsCastBack)
- return addFieldToUninits(LocalChain.add(NeedsCastLocField(FR, DynT)));
- return addFieldToUninits(LocalChain.add(LocField(FR)));
- } else {
- IsAnyFieldInitialized = true;
- return false;
- }
- }
-
- if (DynT->getPointeeType()->isArrayType()) {
+ return addFieldToUninits(LocalChain.add(NeedsCastLocField(FR, DynT)));
+ return addFieldToUninits(LocalChain.add(LocField(FR)));
+ } else {
IsAnyFieldInitialized = true;
return false;
}
-
- llvm_unreachable("All cases are handled!");
}
- assert((isPrimitiveType(DynT->getPointeeType()) || DynT->isAnyPointerType() ||
- DynT->isReferenceType()) &&
+ if (PointeeT->isArrayType()) {
+ IsAnyFieldInitialized = true;
+ return false;
+ }
+
+ assert((isPrimitiveType(PointeeT) || isDereferencableType(PointeeT)) &&
"At this point FR must either have a primitive dynamic type, or it "
"must be a null, undefined, unknown or concrete pointer!");
- if (isPrimitiveUninit(V)) {
+ SVal PointeeV = State->getSVal(R);
+
+ if (isPrimitiveUninit(PointeeV)) {
if (NeedsCastBack)
return addFieldToUninits(LocalChain.add(NeedsCastLocField(FR, DynT)));
return addFieldToUninits(LocalChain.add(LocField(FR)));
@@ -204,47 +197,46 @@
return false;
}
-static llvm::Optional<std::tuple<SVal, QualType, bool>>
-dereference(ProgramStateRef State, const FieldRegion *FR) {
+static llvm::Optional<DereferenceInfo> dereference(ProgramStateRef State,
+ const FieldRegion *FR) {
- DynamicTypeInfo DynTInfo;
- QualType DynT;
+ llvm::SmallSet<const TypedValueRegion *, 5> VisitedRegions;
// If the static type of the field is a void pointer, we need to cast it back
// to the dynamic type before dereferencing.
bool NeedsCastBack = isVoidPointer(FR->getDecl()->getType());
SVal V = State->getSVal(FR);
- assert(V.getAs<loc::MemRegionVal>() && "V must be loc::MemRegionVal!");
+ assert(V.getAsRegion() && "V must have an underlying region!");
- // If V is multiple pointer value, we'll dereference it again (e.g.: int** ->
- // int*).
- // TODO: Dereference according to the dynamic type to avoid infinite loop for
- // these kind of fields:
- // int **ptr = reinterpret_cast<int **>(&ptr);
- while (auto Tmp = V.getAs<loc::MemRegionVal>()) {
- // We can't reason about symbolic regions, assume its initialized.
- // Note that this also avoids a potential infinite recursion, because
- // constructors for list-like classes are checked without being called, and
- // the Static Analyzer will construct a symbolic region for Node *next; or
- // similar code snippets.
- if (Tmp->getRegion()->getSymbolicBase()) {
+ // The region we'd like to acquire.
+ const auto *R = V.getAsRegion()->getAs<TypedValueRegion>();
+ if (!R)
+ return None;
+
+ VisitedRegions.insert(R);
+
+ // We acquire the dynamic type of R,
+ QualType DynT = R->getLocationType();
+
+ while (const MemRegion *Tmp = State->getSVal(R, DynT).getAsRegion()) {
+
+ R = Tmp->getAs<TypedValueRegion>();
+
+ if (!R)
return None;
- }
- DynTInfo = getDynamicTypeInfo(State, Tmp->getRegion());
- if (!DynTInfo.isValid()) {
+ // We found a cyclic pointer, like int *ptr = (int *)&ptr.
+ // TODO: Report these fields too.
+ if (!VisitedRegions.insert(R).second)
return None;
- }
- DynT = DynTInfo.getType();
-
- if (isVoidPointer(DynT)) {
- return None;
- }
-
- V = State->getSVal(*Tmp, DynT);
+ DynT = R->getLocationType();
+ // In order to ensure that this loop terminates, we're also checking the
+ // dynamic type of R, since type hierarchy is finite.
+ if (isDereferencableType(DynT->getPointeeType()))
+ break;
}
- return std::make_tuple(V, DynT, NeedsCastBack);
+ return std::make_pair(R, NeedsCastBack);
}