[analyzer][UninitializedObjectChecker] Refactoring p2.: Moving pointer chasing to a separate file
In this patch, the following classes and functions have been moved to a header file:
FieldChainInfo
FindUninitializedFields
isPrimitiveType
This also meant that they moved from anonymous namespace to clang::ento.
Code related to pointer chasing now relies in its own file.
There's absolutely no functional change in this patch -- its literally just copy pasting.
Differential Revision: https://reviews.llvm.org/D50504
llvm-svn: 339595
diff --git a/clang/lib/StaticAnalyzer/Checkers/UninitializedObject/UninitializedObjectChecker.cpp b/clang/lib/StaticAnalyzer/Checkers/UninitializedObject/UninitializedObjectChecker.cpp
new file mode 100644
index 0000000..c54aff4
--- /dev/null
+++ b/clang/lib/StaticAnalyzer/Checkers/UninitializedObject/UninitializedObjectChecker.cpp
@@ -0,0 +1,487 @@
+//===----- UninitializedObjectChecker.cpp ------------------------*- C++ -*-==//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file defines a checker that reports uninitialized fields in objects
+// created after a constructor call.
+//
+// This checker has several options:
+// - "Pedantic" (boolean). If its not set or is set to false, the checker
+// won't emit warnings for objects that don't have at least one initialized
+// field. This may be set with
+//
+// `-analyzer-config alpha.cplusplus.UninitializedObject:Pedantic=true`.
+//
+// - "NotesAsWarnings" (boolean). If set to true, the checker will emit a
+// warning for each uninitalized field, as opposed to emitting one warning
+// per constructor call, and listing the uninitialized fields that belongs
+// to it in notes. Defaults to false.
+//
+// `-analyzer-config \
+// alpha.cplusplus.UninitializedObject:NotesAsWarnings=true`.
+//
+// - "CheckPointeeInitialization" (boolean). If set to false, the checker will
+// not analyze the pointee of pointer/reference fields, and will only check
+// whether the object itself is initialized. Defaults to false.
+//
+// `-analyzer-config \
+// alpha.cplusplus.UninitializedObject:CheckPointeeInitialization=true`.
+//
+// TODO: With some clever heuristics, some pointers should be dereferenced
+// by default. For example, if the pointee is constructed within the
+// constructor call, it's reasonable to say that no external object
+// references it, and we wouldn't generate multiple report on the same
+// pointee.
+//
+// To read about how the checker works, refer to the comments in
+// UninitializedObject.h.
+//
+// Some of the logic is implemented in UninitializedPointee.cpp, to reduce the
+// complexity of this file.
+//
+//===----------------------------------------------------------------------===//
+
+#include "UninitializedObject.h"
+#include "ClangSACheckers.h"
+#include "clang/StaticAnalyzer/Core/BugReporter/BugType.h"
+#include "clang/StaticAnalyzer/Core/Checker.h"
+#include "clang/StaticAnalyzer/Core/PathSensitive/CheckerContext.h"
+#include "clang/StaticAnalyzer/Core/PathSensitive/DynamicTypeMap.h"
+
+using namespace clang;
+using namespace clang::ento;
+
+namespace {
+
+class UninitializedObjectChecker : public Checker<check::EndFunction> {
+ std::unique_ptr<BuiltinBug> BT_uninitField;
+
+public:
+ // These fields will be initialized when registering the checker.
+ bool IsPedantic;
+ bool ShouldConvertNotesToWarnings;
+ bool CheckPointeeInitialization;
+
+ UninitializedObjectChecker()
+ : BT_uninitField(new BuiltinBug(this, "Uninitialized fields")) {}
+ void checkEndFunction(const ReturnStmt *RS, CheckerContext &C) const;
+};
+
+} // end of anonymous namespace
+
+// Utility function declarations.
+
+/// Returns the object that was constructed by CtorDecl, or None if that isn't
+/// possible.
+// TODO: Refactor this function so that it returns the constructed object's
+// region.
+static Optional<nonloc::LazyCompoundVal>
+getObjectVal(const CXXConstructorDecl *CtorDecl, CheckerContext &Context);
+
+/// Checks whether the object constructed by \p Ctor will be analyzed later
+/// (e.g. if the object is a field of another object, in which case we'd check
+/// it multiple times).
+static bool willObjectBeAnalyzedLater(const CXXConstructorDecl *Ctor,
+ CheckerContext &Context);
+
+/// Constructs a note message for a given FieldChainInfo object.
+static void printNoteMessage(llvm::raw_ostream &Out,
+ const FieldChainInfo &Chain);
+
+/// Returns with Field's name. This is a helper function to get the correct name
+/// even if Field is a captured lambda variable.
+static StringRef getVariableName(const FieldDecl *Field);
+
+//===----------------------------------------------------------------------===//
+// Methods for UninitializedObjectChecker.
+//===----------------------------------------------------------------------===//
+
+void UninitializedObjectChecker::checkEndFunction(
+ const ReturnStmt *RS, CheckerContext &Context) const {
+
+ const auto *CtorDecl = dyn_cast_or_null<CXXConstructorDecl>(
+ Context.getLocationContext()->getDecl());
+ if (!CtorDecl)
+ return;
+
+ if (!CtorDecl->isUserProvided())
+ return;
+
+ if (CtorDecl->getParent()->isUnion())
+ return;
+
+ // This avoids essentially the same error being reported multiple times.
+ if (willObjectBeAnalyzedLater(CtorDecl, Context))
+ return;
+
+ Optional<nonloc::LazyCompoundVal> Object = getObjectVal(CtorDecl, Context);
+ if (!Object)
+ return;
+
+ FindUninitializedFields F(Context.getState(), Object->getRegion(), IsPedantic,
+ CheckPointeeInitialization);
+
+ const UninitFieldSet &UninitFields = F.getUninitFields();
+
+ if (UninitFields.empty())
+ return;
+
+ // There are uninitialized fields in the record.
+
+ ExplodedNode *Node = Context.generateNonFatalErrorNode(Context.getState());
+ if (!Node)
+ return;
+
+ PathDiagnosticLocation LocUsedForUniqueing;
+ const Stmt *CallSite = Context.getStackFrame()->getCallSite();
+ if (CallSite)
+ LocUsedForUniqueing = PathDiagnosticLocation::createBegin(
+ CallSite, Context.getSourceManager(), Node->getLocationContext());
+
+ // For Plist consumers that don't support notes just yet, we'll convert notes
+ // to warnings.
+ if (ShouldConvertNotesToWarnings) {
+ for (const auto &Chain : UninitFields) {
+ SmallString<100> WarningBuf;
+ llvm::raw_svector_ostream WarningOS(WarningBuf);
+
+ printNoteMessage(WarningOS, Chain);
+
+ auto Report = llvm::make_unique<BugReport>(
+ *BT_uninitField, WarningOS.str(), Node, LocUsedForUniqueing,
+ Node->getLocationContext()->getDecl());
+ Context.emitReport(std::move(Report));
+ }
+ return;
+ }
+
+ SmallString<100> WarningBuf;
+ llvm::raw_svector_ostream WarningOS(WarningBuf);
+ WarningOS << UninitFields.size() << " uninitialized field"
+ << (UninitFields.size() == 1 ? "" : "s")
+ << " at the end of the constructor call";
+
+ auto Report = llvm::make_unique<BugReport>(
+ *BT_uninitField, WarningOS.str(), Node, LocUsedForUniqueing,
+ Node->getLocationContext()->getDecl());
+
+ for (const auto &Chain : UninitFields) {
+ SmallString<200> NoteBuf;
+ llvm::raw_svector_ostream NoteOS(NoteBuf);
+
+ printNoteMessage(NoteOS, Chain);
+
+ Report->addNote(NoteOS.str(),
+ PathDiagnosticLocation::create(Chain.getEndOfChain(),
+ Context.getSourceManager()));
+ }
+ Context.emitReport(std::move(Report));
+}
+
+//===----------------------------------------------------------------------===//
+// Methods for FindUninitializedFields.
+//===----------------------------------------------------------------------===//
+
+FindUninitializedFields::FindUninitializedFields(
+ ProgramStateRef State, const TypedValueRegion *const R, bool IsPedantic,
+ bool CheckPointeeInitialization)
+ : State(State), ObjectR(R), IsPedantic(IsPedantic),
+ CheckPointeeInitialization(CheckPointeeInitialization) {}
+
+const UninitFieldSet &FindUninitializedFields::getUninitFields() {
+ isNonUnionUninit(ObjectR, FieldChainInfo(Factory));
+
+ if (!IsPedantic && !IsAnyFieldInitialized)
+ UninitFields.clear();
+
+ return UninitFields;
+}
+
+bool FindUninitializedFields::addFieldToUninits(FieldChainInfo Chain) {
+ if (State->getStateManager().getContext().getSourceManager().isInSystemHeader(
+ Chain.getEndOfChain()->getLocation()))
+ return false;
+
+ return UninitFields.insert(Chain).second;
+}
+
+bool FindUninitializedFields::isNonUnionUninit(const TypedValueRegion *R,
+ FieldChainInfo LocalChain) {
+ assert(R->getValueType()->isRecordType() &&
+ !R->getValueType()->isUnionType() &&
+ "This method only checks non-union record objects!");
+
+ const RecordDecl *RD =
+ R->getValueType()->getAs<RecordType>()->getDecl()->getDefinition();
+ assert(RD && "Referred record has no definition");
+
+ bool ContainsUninitField = false;
+
+ // Are all of this non-union's fields initialized?
+ for (const FieldDecl *I : RD->fields()) {
+
+ const auto FieldVal =
+ State->getLValue(I, loc::MemRegionVal(R)).castAs<loc::MemRegionVal>();
+ const auto *FR = FieldVal.getRegionAs<FieldRegion>();
+ QualType T = I->getType();
+
+ // If LocalChain already contains FR, then we encountered a cyclic
+ // reference. In this case, region FR is already under checking at an
+ // earlier node in the directed tree.
+ if (LocalChain.contains(FR))
+ return false;
+
+ if (T->isStructureOrClassType()) {
+ if (isNonUnionUninit(FR, {LocalChain, FR}))
+ ContainsUninitField = true;
+ continue;
+ }
+
+ if (T->isUnionType()) {
+ if (isUnionUninit(FR)) {
+ if (addFieldToUninits({LocalChain, FR}))
+ ContainsUninitField = true;
+ } else
+ IsAnyFieldInitialized = true;
+ continue;
+ }
+
+ if (T->isArrayType()) {
+ IsAnyFieldInitialized = true;
+ continue;
+ }
+
+ if (T->isPointerType() || T->isReferenceType() || T->isBlockPointerType()) {
+ if (isPointerOrReferenceUninit(FR, LocalChain))
+ ContainsUninitField = true;
+ continue;
+ }
+
+ if (isPrimitiveType(T)) {
+ SVal V = State->getSVal(FieldVal);
+
+ if (isPrimitiveUninit(V)) {
+ if (addFieldToUninits({LocalChain, FR}))
+ ContainsUninitField = true;
+ }
+ continue;
+ }
+
+ llvm_unreachable("All cases are handled!");
+ }
+
+ // Checking bases.
+ // FIXME: As of now, because of `willObjectBeAnalyzedLater`, objects whose
+ // type is a descendant of another type will emit warnings for uninitalized
+ // inherited members.
+ // This is not the only way to analyze bases of an object -- if we didn't
+ // filter them out, and didn't analyze the bases, this checker would run for
+ // each base of the object in order of base initailization and in theory would
+ // find every uninitalized field. This approach could also make handling
+ // diamond inheritances more easily.
+ //
+ // This rule (that a descendant type's cunstructor is responsible for
+ // initializing inherited data members) is not obvious, and should it should
+ // be.
+ const auto *CXXRD = dyn_cast<CXXRecordDecl>(RD);
+ if (!CXXRD)
+ return ContainsUninitField;
+
+ for (const CXXBaseSpecifier &BaseSpec : CXXRD->bases()) {
+ const auto *BaseRegion = State->getLValue(BaseSpec, R)
+ .castAs<loc::MemRegionVal>()
+ .getRegionAs<TypedValueRegion>();
+
+ if (isNonUnionUninit(BaseRegion, LocalChain))
+ ContainsUninitField = true;
+ }
+
+ return ContainsUninitField;
+}
+
+bool FindUninitializedFields::isUnionUninit(const TypedValueRegion *R) {
+ assert(R->getValueType()->isUnionType() &&
+ "This method only checks union objects!");
+ // TODO: Implement support for union fields.
+ return false;
+}
+
+bool FindUninitializedFields::isPrimitiveUninit(const SVal &V) {
+ if (V.isUndef())
+ return true;
+
+ IsAnyFieldInitialized = true;
+ return false;
+}
+
+//===----------------------------------------------------------------------===//
+// Methods for FieldChainInfo.
+//===----------------------------------------------------------------------===//
+
+FieldChainInfo::FieldChainInfo(const FieldChainInfo &Other,
+ const FieldRegion *FR, const bool IsDereferenced)
+ : FieldChainInfo(Other, IsDereferenced) {
+ assert(!contains(FR) && "Can't add a field that is already a part of the "
+ "fieldchain! Is this a cyclic reference?");
+ Chain = Factory.add(FR, Other.Chain);
+}
+
+bool FieldChainInfo::isPointer() const {
+ assert(!Chain.isEmpty() && "Empty fieldchain!");
+ return (*Chain.begin())->getDecl()->getType()->isPointerType();
+}
+
+bool FieldChainInfo::isDereferenced() const {
+ assert(isPointer() && "Only pointers may or may not be dereferenced!");
+ return IsDereferenced;
+}
+
+const FieldDecl *FieldChainInfo::getEndOfChain() const {
+ assert(!Chain.isEmpty() && "Empty fieldchain!");
+ return (*Chain.begin())->getDecl();
+}
+
+// TODO: This function constructs an incorrect string if a void pointer is a
+// part of the chain:
+//
+// struct B { int x; }
+//
+// struct A {
+// void *vptr;
+// A(void* vptr) : vptr(vptr) {}
+// };
+//
+// void f() {
+// B b;
+// A a(&b);
+// }
+//
+// The note message will be "uninitialized field 'this->vptr->x'", even though
+// void pointers can't be dereferenced. This should be changed to "uninitialized
+// field 'static_cast<B*>(this->vptr)->x'".
+//
+// TODO: This function constructs an incorrect fieldchain string in the
+// following case:
+//
+// struct Base { int x; };
+// struct D1 : Base {}; struct D2 : Base {};
+//
+// struct MostDerived : D1, D2 {
+// MostDerived() {}
+// }
+//
+// A call to MostDerived::MostDerived() will cause two notes that say
+// "uninitialized field 'this->x'", but we can't refer to 'x' directly,
+// we need an explicit namespace resolution whether the uninit field was
+// 'D1::x' or 'D2::x'.
+void FieldChainInfo::print(llvm::raw_ostream &Out) const {
+ if (Chain.isEmpty())
+ return;
+
+ const llvm::ImmutableListImpl<const FieldRegion *> *L =
+ Chain.getInternalPointer();
+ printTail(Out, L->getTail());
+ Out << getVariableName(L->getHead()->getDecl());
+}
+
+void FieldChainInfo::printTail(
+ llvm::raw_ostream &Out,
+ const llvm::ImmutableListImpl<const FieldRegion *> *L) {
+ if (!L)
+ return;
+
+ printTail(Out, L->getTail());
+ const FieldDecl *Field = L->getHead()->getDecl();
+ Out << getVariableName(Field);
+ Out << (Field->getType()->isPointerType() ? "->" : ".");
+}
+
+//===----------------------------------------------------------------------===//
+// Utility functions.
+//===----------------------------------------------------------------------===//
+
+static Optional<nonloc::LazyCompoundVal>
+getObjectVal(const CXXConstructorDecl *CtorDecl, CheckerContext &Context) {
+
+ Loc ThisLoc = Context.getSValBuilder().getCXXThis(CtorDecl->getParent(),
+ Context.getStackFrame());
+ // Getting the value for 'this'.
+ SVal This = Context.getState()->getSVal(ThisLoc);
+
+ // Getting the value for '*this'.
+ SVal Object = Context.getState()->getSVal(This.castAs<Loc>());
+
+ return Object.getAs<nonloc::LazyCompoundVal>();
+}
+
+static bool willObjectBeAnalyzedLater(const CXXConstructorDecl *Ctor,
+ CheckerContext &Context) {
+
+ Optional<nonloc::LazyCompoundVal> CurrentObject = getObjectVal(Ctor, Context);
+ if (!CurrentObject)
+ return false;
+
+ const LocationContext *LC = Context.getLocationContext();
+ while ((LC = LC->getParent())) {
+
+ // If \p Ctor was called by another constructor.
+ const auto *OtherCtor = dyn_cast<CXXConstructorDecl>(LC->getDecl());
+ if (!OtherCtor)
+ continue;
+
+ Optional<nonloc::LazyCompoundVal> OtherObject =
+ getObjectVal(OtherCtor, Context);
+ if (!OtherObject)
+ continue;
+
+ // If the CurrentObject is a subregion of OtherObject, it will be analyzed
+ // during the analysis of OtherObject.
+ if (CurrentObject->getRegion()->isSubRegionOf(OtherObject->getRegion()))
+ return true;
+ }
+
+ return false;
+}
+
+static void printNoteMessage(llvm::raw_ostream &Out,
+ const FieldChainInfo &Chain) {
+ if (Chain.isPointer()) {
+ if (Chain.isDereferenced())
+ Out << "uninitialized pointee 'this->";
+ else
+ Out << "uninitialized pointer 'this->";
+ } else
+ Out << "uninitialized field 'this->";
+ Chain.print(Out);
+ Out << "'";
+}
+
+static StringRef getVariableName(const FieldDecl *Field) {
+ // If Field is a captured lambda variable, Field->getName() will return with
+ // an empty string. We can however acquire it's name from the lambda's
+ // captures.
+ const auto *CXXParent = dyn_cast<CXXRecordDecl>(Field->getParent());
+
+ if (CXXParent && CXXParent->isLambda()) {
+ assert(CXXParent->captures_begin());
+ auto It = CXXParent->captures_begin() + Field->getFieldIndex();
+ return It->getCapturedVar()->getName();
+ }
+
+ return Field->getName();
+}
+
+void ento::registerUninitializedObjectChecker(CheckerManager &Mgr) {
+ auto Chk = Mgr.registerChecker<UninitializedObjectChecker>();
+ Chk->IsPedantic = Mgr.getAnalyzerOptions().getBooleanOption(
+ "Pedantic", /*DefaultVal*/ false, Chk);
+ Chk->ShouldConvertNotesToWarnings = Mgr.getAnalyzerOptions().getBooleanOption(
+ "NotesAsWarnings", /*DefaultVal*/ false, Chk);
+ Chk->CheckPointeeInitialization = Mgr.getAnalyzerOptions().getBooleanOption(
+ "CheckPointeeInitialization", /*DefaultVal*/ false, Chk);
+}