}
};
+ /// A reference to an object whose construction we are currently evaluating.
+ struct ObjectUnderConstruction {
+ APValue::LValueBase Base;
+ ArrayRef<APValue::LValuePathEntry> Path;
+ friend bool operator==(const ObjectUnderConstruction &LHS,
+ const ObjectUnderConstruction &RHS) {
+ return LHS.Base == RHS.Base && LHS.Path == RHS.Path;
+ }
+ friend llvm::hash_code hash_value(const ObjectUnderConstruction &Obj) {
+ return llvm::hash_combine(Obj.Base, Obj.Path);
+ }
+ };
+ enum class ConstructionPhase { None, Bases, AfterBases };
+}
+
+namespace llvm {
+template<> struct DenseMapInfo<ObjectUnderConstruction> {
+ using Base = DenseMapInfo<APValue::LValueBase>;
+ static ObjectUnderConstruction getEmptyKey() {
+ return {Base::getEmptyKey(), {}}; }
+ static ObjectUnderConstruction getTombstoneKey() {
+ return {Base::getTombstoneKey(), {}};
+ }
+ static unsigned getHashValue(const ObjectUnderConstruction &Object) {
+ return hash_value(Object);
+ }
+ static bool isEqual(const ObjectUnderConstruction &LHS,
+ const ObjectUnderConstruction &RHS) {
+ return LHS == RHS;
+ }
+};
+}
+
+namespace {
/// EvalInfo - This is a private struct used by the evaluator to capture
/// information about a subexpression as it is folded. It retains information
/// about the AST context, but also maintains information about the folded
/// declaration whose initializer is being evaluated, if any.
APValue *EvaluatingDeclValue;
- /// EvaluatingObject - Pair of the AST node that an lvalue represents and
- /// the call index that that lvalue was allocated in.
- typedef std::pair<APValue::LValueBase, std::pair<unsigned, unsigned>>
- EvaluatingObject;
-
- /// EvaluatingConstructors - Set of objects that are currently being
- /// constructed.
- llvm::DenseSet<EvaluatingObject> EvaluatingConstructors;
+ /// Set of objects that are currently being constructed.
+ llvm::DenseMap<ObjectUnderConstruction, ConstructionPhase>
+ ObjectsUnderConstruction;
struct EvaluatingConstructorRAII {
EvalInfo &EI;
- EvaluatingObject Object;
+ ObjectUnderConstruction Object;
bool DidInsert;
- EvaluatingConstructorRAII(EvalInfo &EI, EvaluatingObject Object)
+ EvaluatingConstructorRAII(EvalInfo &EI, ObjectUnderConstruction Object,
+ bool HasBases)
: EI(EI), Object(Object) {
- DidInsert = EI.EvaluatingConstructors.insert(Object).second;
+ DidInsert =
+ EI.ObjectsUnderConstruction
+ .insert({Object, HasBases ? ConstructionPhase::Bases
+ : ConstructionPhase::AfterBases})
+ .second;
+ }
+ void finishedConstructingBases() {
+ EI.ObjectsUnderConstruction[Object] = ConstructionPhase::AfterBases;
}
~EvaluatingConstructorRAII() {
- if (DidInsert) EI.EvaluatingConstructors.erase(Object);
+ if (DidInsert) EI.ObjectsUnderConstruction.erase(Object);
}
};
- bool isEvaluatingConstructor(APValue::LValueBase Decl, unsigned CallIndex,
- unsigned Version) {
- return EvaluatingConstructors.count(
- EvaluatingObject(Decl, {CallIndex, Version}));
+ ConstructionPhase
+ isEvaluatingConstructor(APValue::LValueBase Base,
+ ArrayRef<APValue::LValuePathEntry> Path) {
+ return ObjectsUnderConstruction.lookup({Base, Path});
}
/// If we're currently speculatively evaluating, the outermost call stack
void setEvaluatingDecl(APValue::LValueBase Base, APValue &Value) {
EvaluatingDecl = Base;
EvaluatingDeclValue = &Value;
- EvaluatingConstructors.insert({Base, {0, 0}});
}
const LangOptions &getLangOpts() const { return Ctx.getLangOpts(); }
/// A handle to a complete object (an object that is not a subobject of
/// another object).
struct CompleteObject {
+ /// The identity of the object.
+ APValue::LValueBase Base;
/// The value of the complete object.
APValue *Value;
/// The type of the complete object.
bool LifetimeStartedInEvaluation;
CompleteObject() : Value(nullptr) {}
- CompleteObject(APValue *Value, QualType Type,
+ CompleteObject(APValue::LValueBase Base, APValue *Value, QualType Type,
bool LifetimeStartedInEvaluation)
- : Value(Value), Type(Type),
+ : Base(Base), Value(Value), Type(Type),
LifetimeStartedInEvaluation(LifetimeStartedInEvaluation) {
assert(Value && "missing value for complete object");
}
};
} // end anonymous namespace
+static QualType getSubobjectType(QualType ObjType, QualType SubobjType,
+ bool IsMutable = false) {
+ // C++ [basic.type.qualifier]p1:
+ // - A const object is an object of type const T or a non-mutable subobject
+ // of a const object.
+ if (ObjType.isConstQualified() && !IsMutable)
+ SubobjType.addConst();
+ // - A volatile object is an object of type const T or a subobject of a
+ // volatile object.
+ if (ObjType.isVolatileQualified())
+ SubobjType.addVolatile();
+ return SubobjType;
+}
+
/// Find the designated sub-object of an rvalue.
template<typename SubobjectHandler>
typename SubobjectHandler::result_type
const FieldDecl *LastField = nullptr;
const bool MayReadMutableMembers =
Obj.LifetimeStartedInEvaluation && Info.getLangOpts().CPlusPlus14;
+ const FieldDecl *VolatileField = nullptr;
// Walk the designator's path to find the subobject.
for (unsigned I = 0, N = Sub.Entries.size(); /**/; ++I) {
if (O->isUninit()) {
if (!Info.checkingPotentialConstantExpression())
- Info.FFDiag(E, diag::note_constexpr_access_uninit) << handler.AccessKind;
+ Info.FFDiag(E, diag::note_constexpr_access_uninit)
+ << handler.AccessKind;
return handler.failed();
}
- if (I == N) {
+ // C++ [class.ctor]p5:
+ // const and volatile semantics are not applied on an object under
+ // construction.
+ if ((ObjType.isConstQualified() || ObjType.isVolatileQualified()) &&
+ ObjType->isRecordType() &&
+ Info.isEvaluatingConstructor(
+ Obj.Base, llvm::makeArrayRef(Sub.Entries.begin(),
+ Sub.Entries.begin() + I)) !=
+ ConstructionPhase::None) {
+ ObjType = Info.Ctx.getCanonicalType(ObjType);
+ ObjType.removeLocalConst();
+ ObjType.removeLocalVolatile();
+ }
+
+ // If this is our last pass, check that the final object type is OK.
+ if (I == N || (I == N - 1 && ObjType->isAnyComplexType())) {
+ // Accesses to volatile objects are prohibited.
+ if (ObjType.isVolatileQualified()) {
+ if (Info.getLangOpts().CPlusPlus) {
+ int DiagKind;
+ SourceLocation Loc;
+ const NamedDecl *Decl = nullptr;
+ if (VolatileField) {
+ DiagKind = 2;
+ Loc = VolatileField->getLocation();
+ Decl = VolatileField;
+ } else if (auto *VD = Obj.Base.dyn_cast<const ValueDecl*>()) {
+ DiagKind = 1;
+ Loc = VD->getLocation();
+ Decl = VD;
+ } else {
+ DiagKind = 0;
+ if (auto *E = Obj.Base.dyn_cast<const Expr *>())
+ Loc = E->getExprLoc();
+ }
+ Info.FFDiag(E, diag::note_constexpr_access_volatile_obj, 1)
+ << handler.AccessKind << DiagKind << Decl;
+ Info.Note(Loc, diag::note_constexpr_volatile_here) << DiagKind;
+ } else {
+ Info.FFDiag(E, diag::note_invalid_subexpr_in_const_expr);
+ }
+ return handler.failed();
+ }
+
// If we are reading an object of class type, there may still be more
// things we need to check: if there are any mutable subobjects, we
// cannot perform this read. (This only happens when performing a trivial
if (ObjType->isRecordType() && handler.AccessKind == AK_Read &&
!MayReadMutableMembers && diagnoseUnreadableFields(Info, E, ObjType))
return handler.failed();
+ }
+ if (I == N) {
if (!handler.found(*O, ObjType))
return false;
return handler.failed();
}
- bool WasConstQualified = ObjType.isConstQualified();
- ObjType = ObjType->castAs<ComplexType>()->getElementType();
- if (WasConstQualified)
- ObjType.addConst();
+ ObjType = getSubobjectType(
+ ObjType, ObjType->castAs<ComplexType>()->getElementType());
assert(I == N - 1 && "extracting subobject of scalar?");
if (O->isComplexInt()) {
} else
O = &O->getStructField(Field->getFieldIndex());
- bool WasConstQualified = ObjType.isConstQualified();
- ObjType = Field->getType();
- if (WasConstQualified && !Field->isMutable())
- ObjType.addConst();
-
- if (ObjType.isVolatileQualified()) {
- if (Info.getLangOpts().CPlusPlus) {
- // FIXME: Include a description of the path to the volatile subobject.
- Info.FFDiag(E, diag::note_constexpr_access_volatile_obj, 1)
- << handler.AccessKind << 2 << Field;
- Info.Note(Field->getLocation(), diag::note_declared_at);
- } else {
- Info.FFDiag(E, diag::note_invalid_subexpr_in_const_expr);
- }
- return handler.failed();
- }
-
+ ObjType = getSubobjectType(ObjType, Field->getType(), Field->isMutable());
LastField = Field;
+ if (Field->getType().isVolatileQualified())
+ VolatileField = Field;
} else {
// Next subobject is a base class.
const CXXRecordDecl *Derived = ObjType->getAsCXXRecordDecl();
const CXXRecordDecl *Base = getAsBaseClass(Sub.Entries[I]);
O = &O->getStructBase(getBaseIndex(Derived, Base));
- bool WasConstQualified = ObjType.isConstQualified();
- ObjType = Info.Ctx.getRecordType(Base);
- if (WasConstQualified)
- ObjType.addConst();
+ ObjType = getSubobjectType(ObjType, Info.Ctx.getRecordType(Base));
}
}
}
return CompleteObject();
}
- // Accesses of volatile-qualified objects are not allowed.
- if (BaseType.isVolatileQualified()) {
- if (Info.getLangOpts().CPlusPlus) {
- Info.FFDiag(E, diag::note_constexpr_access_volatile_obj, 1)
- << AK << 1 << VD;
- Info.Note(VD->getLocation(), diag::note_declared_at);
- } else {
- Info.FFDiag(E);
- }
- return CompleteObject();
- }
-
// Unless we're looking at a local variable or argument in a constexpr call,
// the variable we're reading must be const.
if (!Frame) {
// OK, we can read and modify an object if we're in the process of
// evaluating its initializer, because its lifetime began in this
// evaluation.
+ LifetimeStartedInEvaluation = true;
} else if (AK != AK_Read) {
// All the remaining cases only permit reading.
Info.FFDiag(E, diag::note_constexpr_modify_global);
BaseVal = Frame->getTemporary(Base, LVal.Base.getVersion());
assert(BaseVal && "missing value for temporary");
}
-
- // Volatile temporary objects cannot be accessed in constant expressions.
- if (BaseType.isVolatileQualified()) {
- if (Info.getLangOpts().CPlusPlus) {
- Info.FFDiag(E, diag::note_constexpr_access_volatile_obj, 1)
- << AK << 0;
- Info.Note(Base->getExprLoc(), diag::note_constexpr_temporary_here);
- } else {
- Info.FFDiag(E);
- }
- return CompleteObject();
- }
- }
-
- // During the construction of an object, it is not yet 'const'.
- // FIXME: This doesn't do quite the right thing for const subobjects of the
- // object under construction.
- if (Info.isEvaluatingConstructor(LVal.getLValueBase(),
- LVal.getLValueCallIndex(),
- LVal.getLValueVersion())) {
- BaseType = Info.Ctx.getCanonicalType(BaseType);
- BaseType.removeLocalConst();
- LifetimeStartedInEvaluation = true;
}
// In C++14, we can't safely access any mutable state when we might be
(AK != AK_Read && Depth < Info.SpeculativeEvaluationDepth))
return CompleteObject();
- return CompleteObject(BaseVal, BaseType, LifetimeStartedInEvaluation);
+ return CompleteObject(LVal.getLValueBase(), BaseVal, BaseType,
+ LifetimeStartedInEvaluation);
}
/// Perform an lvalue-to-rvalue conversion on the given glvalue. This
APValue Lit;
if (!Evaluate(Lit, Info, CLE->getInitializer()))
return false;
- CompleteObject LitObj(&Lit, Base->getType(), false);
+ CompleteObject LitObj(LVal.Base, &Lit, Base->getType(), false);
return extractSubobject(Info, Conv, LitObj, LVal.Designator, RVal);
} else if (isa<StringLiteral>(Base) || isa<PredefinedExpr>(Base)) {
// Special-case character extraction so we don't have to construct an
}
EvalInfo::EvaluatingConstructorRAII EvalObj(
- Info, {This.getLValueBase(),
- {This.getLValueCallIndex(), This.getLValueVersion()}});
+ Info,
+ ObjectUnderConstruction{This.getLValueBase(), This.Designator.Entries},
+ RD->getNumBases());
CallStackFrame Frame(Info, CallLoc, Definition, &This, ArgValues);
// FIXME: Creating an APValue just to hold a nonexistent return value is
BaseType->getAsCXXRecordDecl(), &Layout))
return false;
Value = &Result.getStructBase(BasesSeen++);
+
+ // This is the point at which the dynamic type of the object becomes this
+ // class type.
+ if (BasesSeen == RD->getNumBases())
+ EvalObj.finishedConstructingBases();
} else if ((FD = I->getMember())) {
if (!HandleLValueMember(Info, I->getInit(), Subobject, FD, &Layout))
return false;
/// A member expression where the object is a prvalue is itself a prvalue.
bool VisitMemberExpr(const MemberExpr *E) {
+ assert(!Info.Ctx.getLangOpts().CPlusPlus11 &&
+ "missing temporary materialization conversion");
assert(!E->isArrow() && "missing call to bound member function?");
APValue Val;
assert(BaseTy->castAs<RecordType>()->getDecl()->getCanonicalDecl() ==
FD->getParent()->getCanonicalDecl() && "record / field mismatch");
- CompleteObject Obj(&Val, BaseTy, true);
+ // Note: there is no lvalue base here. But this case should only ever
+ // happen in C or in C++98, where we cannot be evaluating a constexpr
+ // constructor, which is the only case the base matters.
+ CompleteObject Obj(APValue::LValueBase(), &Val, BaseTy, true);
SubobjectDesignator Designator(BaseTy);
Designator.addDeclUnchecked(FD);
const RecordDecl *RD = E->getType()->castAs<RecordType>()->getDecl();
if (RD->isInvalidDecl()) return false;
const ASTRecordLayout &Layout = Info.Ctx.getASTRecordLayout(RD);
+ auto *CXXRD = dyn_cast<CXXRecordDecl>(RD);
+
+ EvalInfo::EvaluatingConstructorRAII EvalObj(
+ Info,
+ ObjectUnderConstruction{This.getLValueBase(), This.Designator.Entries},
+ CXXRD && CXXRD->getNumBases());
if (RD->isUnion()) {
const FieldDecl *Field = E->getInitializedFieldInUnion();
return EvaluateInPlace(Result.getUnionValue(), Info, Subobject, InitExpr);
}
- auto *CXXRD = dyn_cast<CXXRecordDecl>(RD);
if (Result.isUninit())
Result = APValue(APValue::UninitStruct(), CXXRD ? CXXRD->getNumBases() : 0,
std::distance(RD->field_begin(), RD->field_end()));
bool Success = true;
// Initialize base classes.
- if (CXXRD) {
+ if (CXXRD && CXXRD->getNumBases()) {
for (const auto &Base : CXXRD->bases()) {
assert(ElementNo < E->getNumInits() && "missing init for base class");
const Expr *Init = E->getInit(ElementNo);
}
++ElementNo;
}
+
+ EvalObj.finishedConstructingBases();
}
// Initialize members.
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