r340984 - [analyzer] Support modeling no-op BaseToDerived casts in ExprEngine.
Artem Dergachev via cfe-commits
cfe-commits at lists.llvm.org
Wed Aug 29 15:43:31 PDT 2018
Author: dergachev
Date: Wed Aug 29 15:43:31 2018
New Revision: 340984
URL: http://llvm.org/viewvc/llvm-project?rev=340984&view=rev
Log:
[analyzer] Support modeling no-op BaseToDerived casts in ExprEngine.
Introduce a new MemRegion sub-class, CXXDerivedObjectRegion, which is
the opposite of CXXBaseObjectRegion, to represent such casts. Such region is
a bit weird because it is by design bigger than its super-region.
But it's not harmful when it is put on top of a SymbolicRegion
that has unknown extent anyway.
Offset computation for CXXDerivedObjectRegion and proper modeling of casts
still remains to be implemented.
Differential Revision: https://reviews.llvm.org/D51191
Modified:
cfe/trunk/include/clang/StaticAnalyzer/Core/PathSensitive/MemRegion.h
cfe/trunk/include/clang/StaticAnalyzer/Core/PathSensitive/Regions.def
cfe/trunk/lib/StaticAnalyzer/Core/MemRegion.cpp
cfe/trunk/lib/StaticAnalyzer/Core/RegionStore.cpp
cfe/trunk/lib/StaticAnalyzer/Core/Store.cpp
cfe/trunk/test/Analysis/casts.cpp
Modified: cfe/trunk/include/clang/StaticAnalyzer/Core/PathSensitive/MemRegion.h
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/include/clang/StaticAnalyzer/Core/PathSensitive/MemRegion.h?rev=340984&r1=340983&r2=340984&view=diff
==============================================================================
--- cfe/trunk/include/clang/StaticAnalyzer/Core/PathSensitive/MemRegion.h (original)
+++ cfe/trunk/include/clang/StaticAnalyzer/Core/PathSensitive/MemRegion.h Wed Aug 29 15:43:31 2018
@@ -122,7 +122,7 @@ public:
/// Each region is a subregion of itself.
virtual bool isSubRegionOf(const MemRegion *R) const;
- const MemRegion *StripCasts(bool StripBaseCasts = true) const;
+ const MemRegion *StripCasts(bool StripBaseAndDerivedCasts = true) const;
/// If this is a symbolic region, returns the region. Otherwise,
/// goes up the base chain looking for the first symbolic base region.
@@ -1176,6 +1176,47 @@ public:
}
};
+// CXXDerivedObjectRegion represents a derived-class object that surrounds
+// a C++ object. It is identified by the derived class declaration and the
+// region of its parent object. It is a bit counter-intuitive (but not otherwise
+// unseen) that this region represents a larger segment of memory that its
+// super-region.
+class CXXDerivedObjectRegion : public TypedValueRegion {
+ friend class MemRegionManager;
+
+ const CXXRecordDecl *DerivedD;
+
+ CXXDerivedObjectRegion(const CXXRecordDecl *DerivedD, const SubRegion *SReg)
+ : TypedValueRegion(SReg, CXXDerivedObjectRegionKind), DerivedD(DerivedD) {
+ assert(DerivedD);
+ // In case of a concrete region, it should always be possible to model
+ // the base-to-derived cast by undoing a previous derived-to-base cast,
+ // otherwise the cast is most likely ill-formed.
+ assert(SReg->getSymbolicBase() &&
+ "Should have unwrapped a base region instead!");
+ }
+
+ static void ProfileRegion(llvm::FoldingSetNodeID &ID, const CXXRecordDecl *RD,
+ const MemRegion *SReg);
+
+public:
+ const CXXRecordDecl *getDecl() const { return DerivedD; }
+
+ QualType getValueType() const override;
+
+ void dumpToStream(raw_ostream &os) const override;
+
+ void Profile(llvm::FoldingSetNodeID &ID) const override;
+
+ bool canPrintPrettyAsExpr() const override;
+
+ void printPrettyAsExpr(raw_ostream &os) const override;
+
+ static bool classof(const MemRegion *region) {
+ return region->getKind() == CXXDerivedObjectRegionKind;
+ }
+};
+
template<typename RegionTy>
const RegionTy* MemRegion::getAs() const {
if (const auto *RT = dyn_cast<RegionTy>(this))
@@ -1326,6 +1367,14 @@ public:
baseReg->isVirtual());
}
+ /// Create a CXXDerivedObjectRegion with the given derived class for region
+ /// \p Super. This should not be used for casting an existing
+ /// CXXBaseObjectRegion back to the derived type; instead, CXXBaseObjectRegion
+ /// should be removed.
+ const CXXDerivedObjectRegion *
+ getCXXDerivedObjectRegion(const CXXRecordDecl *BaseClass,
+ const SubRegion *Super);
+
const FunctionCodeRegion *getFunctionCodeRegion(const NamedDecl *FD);
const BlockCodeRegion *getBlockCodeRegion(const BlockDecl *BD,
CanQualType locTy,
Modified: cfe/trunk/include/clang/StaticAnalyzer/Core/PathSensitive/Regions.def
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/include/clang/StaticAnalyzer/Core/PathSensitive/Regions.def?rev=340984&r1=340983&r2=340984&view=diff
==============================================================================
--- cfe/trunk/include/clang/StaticAnalyzer/Core/PathSensitive/Regions.def (original)
+++ cfe/trunk/include/clang/StaticAnalyzer/Core/PathSensitive/Regions.def Wed Aug 29 15:43:31 2018
@@ -68,6 +68,7 @@ ABSTRACT_REGION(SubRegion, MemRegion)
ABSTRACT_REGION(TypedValueRegion, TypedRegion)
REGION(CompoundLiteralRegion, TypedValueRegion)
REGION(CXXBaseObjectRegion, TypedValueRegion)
+ REGION(CXXDerivedObjectRegion, TypedValueRegion)
REGION(CXXTempObjectRegion, TypedValueRegion)
REGION(CXXThisRegion, TypedValueRegion)
ABSTRACT_REGION(DeclRegion, TypedValueRegion)
Modified: cfe/trunk/lib/StaticAnalyzer/Core/MemRegion.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/StaticAnalyzer/Core/MemRegion.cpp?rev=340984&r1=340983&r2=340984&view=diff
==============================================================================
--- cfe/trunk/lib/StaticAnalyzer/Core/MemRegion.cpp (original)
+++ cfe/trunk/lib/StaticAnalyzer/Core/MemRegion.cpp Wed Aug 29 15:43:31 2018
@@ -225,6 +225,10 @@ QualType CXXBaseObjectRegion::getValueTy
return QualType(getDecl()->getTypeForDecl(), 0);
}
+QualType CXXDerivedObjectRegion::getValueType() const {
+ return QualType(getDecl()->getTypeForDecl(), 0);
+}
+
//===----------------------------------------------------------------------===//
// FoldingSet profiling.
//===----------------------------------------------------------------------===//
@@ -404,6 +408,17 @@ void CXXBaseObjectRegion::Profile(llvm::
ProfileRegion(ID, getDecl(), isVirtual(), superRegion);
}
+void CXXDerivedObjectRegion::ProfileRegion(llvm::FoldingSetNodeID &ID,
+ const CXXRecordDecl *RD,
+ const MemRegion *SReg) {
+ ID.AddPointer(RD);
+ ID.AddPointer(SReg);
+}
+
+void CXXDerivedObjectRegion::Profile(llvm::FoldingSetNodeID &ID) const {
+ ProfileRegion(ID, getDecl(), superRegion);
+}
+
//===----------------------------------------------------------------------===//
// Region anchors.
//===----------------------------------------------------------------------===//
@@ -475,7 +490,11 @@ void CXXTempObjectRegion::dumpToStream(r
}
void CXXBaseObjectRegion::dumpToStream(raw_ostream &os) const {
- os << "base{" << superRegion << ',' << getDecl()->getName() << '}';
+ os << "Base{" << superRegion << ',' << getDecl()->getName() << '}';
+}
+
+void CXXDerivedObjectRegion::dumpToStream(raw_ostream &os) const {
+ os << "Derived{" << superRegion << ',' << getDecl()->getName() << '}';
}
void CXXThisRegion::dumpToStream(raw_ostream &os) const {
@@ -483,7 +502,7 @@ void CXXThisRegion::dumpToStream(raw_ost
}
void ElementRegion::dumpToStream(raw_ostream &os) const {
- os << "element{" << superRegion << ','
+ os << "Element{" << superRegion << ','
<< Index << ',' << getElementType().getAsString() << '}';
}
@@ -492,7 +511,7 @@ void FieldRegion::dumpToStream(raw_ostre
}
void ObjCIvarRegion::dumpToStream(raw_ostream &os) const {
- os << "ivar{" << superRegion << ',' << *getDecl() << '}';
+ os << "Ivar{" << superRegion << ',' << *getDecl() << '}';
}
void StringRegion::dumpToStream(raw_ostream &os) const {
@@ -630,6 +649,14 @@ void CXXBaseObjectRegion::printPrettyAsE
superRegion->printPrettyAsExpr(os);
}
+bool CXXDerivedObjectRegion::canPrintPrettyAsExpr() const {
+ return superRegion->canPrintPrettyAsExpr();
+}
+
+void CXXDerivedObjectRegion::printPrettyAsExpr(raw_ostream &os) const {
+ superRegion->printPrettyAsExpr(os);
+}
+
std::string MemRegion::getDescriptiveName(bool UseQuotes) const {
std::string VariableName;
std::string ArrayIndices;
@@ -1061,6 +1088,12 @@ MemRegionManager::getCXXBaseObjectRegion
return getSubRegion<CXXBaseObjectRegion>(RD, IsVirtual, Super);
}
+const CXXDerivedObjectRegion *
+MemRegionManager::getCXXDerivedObjectRegion(const CXXRecordDecl *RD,
+ const SubRegion *Super) {
+ return getSubRegion<CXXDerivedObjectRegion>(RD, Super);
+}
+
const CXXThisRegion*
MemRegionManager::getCXXThisRegion(QualType thisPointerTy,
const LocationContext *LC) {
@@ -1131,6 +1164,7 @@ const MemRegion *MemRegion::getBaseRegio
case MemRegion::FieldRegionKind:
case MemRegion::ObjCIvarRegionKind:
case MemRegion::CXXBaseObjectRegionKind:
+ case MemRegion::CXXDerivedObjectRegionKind:
R = cast<SubRegion>(R)->getSuperRegion();
continue;
default:
@@ -1149,7 +1183,7 @@ bool MemRegion::isSubRegionOf(const MemR
// View handling.
//===----------------------------------------------------------------------===//
-const MemRegion *MemRegion::StripCasts(bool StripBaseCasts) const {
+const MemRegion *MemRegion::StripCasts(bool StripBaseAndDerivedCasts) const {
const MemRegion *R = this;
while (true) {
switch (R->getKind()) {
@@ -1161,9 +1195,10 @@ const MemRegion *MemRegion::StripCasts(b
break;
}
case CXXBaseObjectRegionKind:
- if (!StripBaseCasts)
+ case CXXDerivedObjectRegionKind:
+ if (!StripBaseAndDerivedCasts)
return R;
- R = cast<CXXBaseObjectRegion>(R)->getSuperRegion();
+ R = cast<TypedValueRegion>(R)->getSuperRegion();
break;
default:
return R;
@@ -1344,6 +1379,12 @@ static RegionOffset calculateOffset(cons
Offset += BaseOffset.getQuantity() * R->getContext().getCharWidth();
break;
}
+
+ case MemRegion::CXXDerivedObjectRegionKind: {
+ // TODO: Store the base type in the CXXDerivedObjectRegion and use it.
+ goto Finish;
+ }
+
case MemRegion::ElementRegionKind: {
const auto *ER = cast<ElementRegion>(R);
R = ER->getSuperRegion();
Modified: cfe/trunk/lib/StaticAnalyzer/Core/RegionStore.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/StaticAnalyzer/Core/RegionStore.cpp?rev=340984&r1=340983&r2=340984&view=diff
==============================================================================
--- cfe/trunk/lib/StaticAnalyzer/Core/RegionStore.cpp (original)
+++ cfe/trunk/lib/StaticAnalyzer/Core/RegionStore.cpp Wed Aug 29 15:43:31 2018
@@ -62,7 +62,9 @@ private:
: P(r, k), Data(offset) {
assert(r && "Must have known regions.");
assert(getOffset() == offset && "Failed to store offset");
- assert((r == r->getBaseRegion() || isa<ObjCIvarRegion>(r)) && "Not a base");
+ assert((r == r->getBaseRegion() || isa<ObjCIvarRegion>(r) ||
+ isa <CXXDerivedObjectRegion>(r)) &&
+ "Not a base");
}
public:
Modified: cfe/trunk/lib/StaticAnalyzer/Core/Store.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/StaticAnalyzer/Core/Store.cpp?rev=340984&r1=340983&r2=340984&view=diff
==============================================================================
--- cfe/trunk/lib/StaticAnalyzer/Core/Store.cpp (original)
+++ cfe/trunk/lib/StaticAnalyzer/Core/Store.cpp Wed Aug 29 15:43:31 2018
@@ -138,6 +138,7 @@ const MemRegion *StoreManager::castRegio
case MemRegion::VarRegionKind:
case MemRegion::CXXTempObjectRegionKind:
case MemRegion::CXXBaseObjectRegionKind:
+ case MemRegion::CXXDerivedObjectRegionKind:
return MakeElementRegion(cast<SubRegion>(R), PointeeTy);
case MemRegion::ElementRegionKind: {
@@ -272,9 +273,8 @@ SVal StoreManager::evalDerivedToBase(SVa
SVal StoreManager::evalDerivedToBase(SVal Derived, QualType BaseType,
bool IsVirtual) {
- Optional<loc::MemRegionVal> DerivedRegVal =
- Derived.getAs<loc::MemRegionVal>();
- if (!DerivedRegVal)
+ const MemRegion *DerivedReg = Derived.getAsRegion();
+ if (!DerivedReg)
return Derived;
const CXXRecordDecl *BaseDecl = BaseType->getPointeeCXXRecordDecl();
@@ -282,8 +282,18 @@ SVal StoreManager::evalDerivedToBase(SVa
BaseDecl = BaseType->getAsCXXRecordDecl();
assert(BaseDecl && "not a C++ object?");
+ if (const auto *AlreadyDerivedReg =
+ dyn_cast<CXXDerivedObjectRegion>(DerivedReg)) {
+ if (const auto *SR =
+ dyn_cast<SymbolicRegion>(AlreadyDerivedReg->getSuperRegion()))
+ if (SR->getSymbol()->getType()->getPointeeCXXRecordDecl() == BaseDecl)
+ return loc::MemRegionVal(SR);
+
+ DerivedReg = AlreadyDerivedReg->getSuperRegion();
+ }
+
const MemRegion *BaseReg = MRMgr.getCXXBaseObjectRegion(
- BaseDecl, cast<SubRegion>(DerivedRegVal->getRegion()), IsVirtual);
+ BaseDecl, cast<SubRegion>(DerivedReg), IsVirtual);
return loc::MemRegionVal(BaseReg);
}
@@ -365,6 +375,10 @@ SVal StoreManager::attemptDownCast(SVal
MR = Uncasted;
}
+ if (const auto *SR = dyn_cast<SymbolicRegion>(MR)) {
+ return loc::MemRegionVal(MRMgr.getCXXDerivedObjectRegion(TargetClass, SR));
+ }
+
// We failed if the region we ended up with has perfect type info.
Failed = isa<TypedValueRegion>(MR);
return UnknownVal();
Modified: cfe/trunk/test/Analysis/casts.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/Analysis/casts.cpp?rev=340984&r1=340983&r2=340984&view=diff
==============================================================================
--- cfe/trunk/test/Analysis/casts.cpp (original)
+++ cfe/trunk/test/Analysis/casts.cpp Wed Aug 29 15:43:31 2018
@@ -1,4 +1,6 @@
-// RUN: %clang_analyze_cc1 -analyzer-checker=core -analyzer-store=region -verify %s
+// RUN: %clang_analyze_cc1 -analyzer-checker=core,debug.ExprInspection -analyzer-store=region -verify %s
+
+void clang_analyzer_eval(bool);
bool PR14634(int x) {
double y = (double)x;
@@ -41,3 +43,32 @@ bool retrievePointerFromBoolean(int *p)
*reinterpret_cast<int **>(&q) = p;
return q;
}
+
+namespace base_to_derived {
+struct A {};
+struct B : public A{};
+
+void foo(A* a) {
+ B* b = (B* ) a;
+ A* a2 = (A *) b;
+ clang_analyzer_eval(a2 == a); // expected-warning{{TRUE}}
+}
+}
+
+namespace base_to_derived_double_inheritance {
+struct A {
+ int x;
+};
+struct B {
+ int y;
+};
+struct C : A, B {};
+
+void foo(B *b) {
+ C *c = (C *)b;
+ b->y = 1;
+ clang_analyzer_eval(c->x); // expected-warning{{UNKNOWN}}
+ clang_analyzer_eval(c->y); // expected-warning{{TRUE}}
+}
+}
+
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