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Remove CXXRecordDecl flags which are unused after r158289. 

We need an efficient mechanism to determine whether a defaulted default
constructor is constexpr, in order to determine whether a class is a literal
type, so keep the incrementally-built form on CXXRecordDecl. Remove the
on-demand computation of same, so that we only have one method for determining
whether a default constructor is constexpr. This doesn't affect correctness,
since default constructor lookup is much simpler than selecting a constructor
for copying or moving.

We don't need a corresponding mechanism for defaulted copy or move constructors,
since they can't affect whether a type is a literal type. Conversely, checking
whether such functions are constexpr can require non-trivial effort, so we defer
such checks until the copy or move constructor is required.

Thus we now only compute whether a copy or move constructor is constexpr on
demand, and only compute whether a default constructor is constexpr in advance.
This is unfortunate, but seems like the best solution.

llvm-svn: 158290
This commit is contained in:
Richard Smith 2012-06-10 07:07:24 +00:00
parent b58000950e
commit 4086a13df8
6 changed files with 22 additions and 152 deletions
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44
clang/include/clang/AST/DeclCXX.h
View File

@ -385,26 +385,10 @@ class CXXRecordDecl : public RecordDecl {
/// constructor for this class would be constexpr.
bool DefaultedDefaultConstructorIsConstexpr : 1;
/// DefaultedCopyConstructorIsConstexpr - True if a defaulted copy
/// constructor for this class would be constexpr.
bool DefaultedCopyConstructorIsConstexpr : 1;
/// DefaultedMoveConstructorIsConstexpr - True if a defaulted move
/// constructor for this class would be constexpr.
bool DefaultedMoveConstructorIsConstexpr : 1;
/// HasConstexprDefaultConstructor - True if this class has a constexpr
/// default constructor (either user-declared or implicitly declared).
bool HasConstexprDefaultConstructor : 1;
/// HasConstexprCopyConstructor - True if this class has a constexpr copy
/// constructor (either user-declared or implicitly declared).
bool HasConstexprCopyConstructor : 1;
/// HasConstexprMoveConstructor - True if this class has a constexpr move
/// constructor (either user-declared or implicitly declared).
bool HasConstexprMoveConstructor : 1;
/// HasTrivialCopyConstructor - True when this class has a trivial copy
/// constructor.
///
@ -1105,18 +1089,6 @@ public:
(!isUnion() || hasInClassInitializer());
}
/// defaultedCopyConstructorIsConstexpr - Whether a defaulted copy
/// constructor for this class would be constexpr.
bool defaultedCopyConstructorIsConstexpr() const {
return data().DefaultedCopyConstructorIsConstexpr;
}
/// defaultedMoveConstructorIsConstexpr - Whether a defaulted move
/// constructor for this class would be constexpr.
bool defaultedMoveConstructorIsConstexpr() const {
return data().DefaultedMoveConstructorIsConstexpr;
}
/// hasConstexprDefaultConstructor - Whether this class has a constexpr
/// default constructor.
bool hasConstexprDefaultConstructor() const {
@ -1125,22 +1097,6 @@ public:
defaultedDefaultConstructorIsConstexpr());
}
/// hasConstexprCopyConstructor - Whether this class has a constexpr copy
/// constructor.
bool hasConstexprCopyConstructor() const {
return data().HasConstexprCopyConstructor ||
(!data().DeclaredCopyConstructor &&
data().DefaultedCopyConstructorIsConstexpr);
}
/// hasConstexprMoveConstructor - Whether this class has a constexpr move
/// constructor.
bool hasConstexprMoveConstructor() const {
return data().HasConstexprMoveConstructor ||
(needsImplicitMoveConstructor() &&
data().DefaultedMoveConstructorIsConstexpr);
}
// hasTrivialCopyConstructor - Whether this class has a trivial copy
// constructor (C++ [class.copy]p6, C++0x [class.copy]p13)
bool hasTrivialCopyConstructor() const {

6
clang/lib/AST/ASTImporter.cpp
View File

@ -1858,14 +1858,8 @@ bool ASTNodeImporter::ImportDefinition(RecordDecl *From, RecordDecl *To,
= FromData.HasConstexprNonCopyMoveConstructor;
ToData.DefaultedDefaultConstructorIsConstexpr
= FromData.DefaultedDefaultConstructorIsConstexpr;
ToData.DefaultedCopyConstructorIsConstexpr
= FromData.DefaultedCopyConstructorIsConstexpr;
ToData.DefaultedMoveConstructorIsConstexpr
= FromData.DefaultedMoveConstructorIsConstexpr;
ToData.HasConstexprDefaultConstructor
= FromData.HasConstexprDefaultConstructor;
ToData.HasConstexprCopyConstructor = FromData.HasConstexprCopyConstructor;
ToData.HasConstexprMoveConstructor = FromData.HasConstexprMoveConstructor;
ToData.HasTrivialCopyConstructor = FromData.HasTrivialCopyConstructor;
ToData.HasTrivialMoveConstructor = FromData.HasTrivialMoveConstructor;
ToData.HasTrivialCopyAssignment = FromData.HasTrivialCopyAssignment;

74
clang/lib/AST/DeclCXX.cpp
View File

@ -47,10 +47,7 @@ CXXRecordDecl::DefinitionData::DefinitionData(CXXRecordDecl *D)
HasTrivialDefaultConstructor(true),
HasConstexprNonCopyMoveConstructor(false),
DefaultedDefaultConstructorIsConstexpr(true),
DefaultedCopyConstructorIsConstexpr(true),
DefaultedMoveConstructorIsConstexpr(true),
HasConstexprDefaultConstructor(false), HasConstexprCopyConstructor(false),
HasConstexprMoveConstructor(false), HasTrivialCopyConstructor(true),
HasConstexprDefaultConstructor(false), HasTrivialCopyConstructor(true),
HasTrivialMoveConstructor(true), HasTrivialCopyAssignment(true),
HasTrivialMoveAssignment(true), HasTrivialDestructor(true),
HasIrrelevantDestructor(true),
@ -220,8 +217,6 @@ CXXRecordDecl::setBases(CXXBaseSpecifier const * const *Bases,
// In the definition of a constexpr constructor [...]
// -- the class shall not have any virtual base classes
data().DefaultedDefaultConstructorIsConstexpr = false;
data().DefaultedCopyConstructorIsConstexpr = false;
data().DefaultedMoveConstructorIsConstexpr = false;
} else {
// C++ [class.ctor]p5:
// A default constructor is trivial [...] if:
@ -260,25 +255,6 @@ CXXRecordDecl::setBases(CXXBaseSpecifier const * const *Bases,
// default constructor is constexpr.
if (!BaseClassDecl->hasConstexprDefaultConstructor())
data().DefaultedDefaultConstructorIsConstexpr = false;
// C++11 [class.copy]p13:
// If the implicitly-defined constructor would satisfy the requirements
// of a constexpr constructor, the implicitly-defined constructor is
// constexpr.
// C++11 [dcl.constexpr]p4:
// -- every constructor involved in initializing [...] base class
// sub-objects shall be a constexpr constructor
if (!BaseClassDecl->hasConstexprCopyConstructor())
data().DefaultedCopyConstructorIsConstexpr = false;
if (BaseClassDecl->hasDeclaredMoveConstructor() ||
BaseClassDecl->needsImplicitMoveConstructor())
// FIXME: If the implicit move constructor generated for the base class
// would be ill-formed, the implicit move constructor generated for the
// derived class calls the base class' copy constructor.
data().DefaultedMoveConstructorIsConstexpr &=
BaseClassDecl->hasConstexprMoveConstructor();
else if (!BaseClassDecl->hasConstexprCopyConstructor())
data().DefaultedMoveConstructorIsConstexpr = false;
}
// C++ [class.ctor]p3:
@ -471,11 +447,7 @@ void CXXRecordDecl::markedVirtualFunctionPure() {
}
void CXXRecordDecl::markedConstructorConstexpr(CXXConstructorDecl *CD) {
if (CD->isCopyConstructor())
data().HasConstexprCopyConstructor = true;
else if (CD->isMoveConstructor())
data().HasConstexprMoveConstructor = true;
else
if (!CD->isCopyOrMoveConstructor())
data().HasConstexprNonCopyMoveConstructor = true;
if (CD->isDefaultConstructor())
@ -558,12 +530,8 @@ void CXXRecordDecl::addedMember(Decl *D) {
}
} else if (Constructor->isCopyConstructor()) {
data().DeclaredCopyConstructor = true;
if (Constructor->isConstexpr())
data().HasConstexprCopyConstructor = true;
} else if (Constructor->isMoveConstructor()) {
data().DeclaredMoveConstructor = true;
if (Constructor->isConstexpr())
data().HasConstexprMoveConstructor = true;
} else
goto NotASpecialMember;
return;
@ -620,9 +588,6 @@ NotASpecialMember:;
// user-provided [...]
if (UserProvided)
data().HasTrivialCopyConstructor = false;
if (Constructor->isConstexpr())
data().HasConstexprCopyConstructor = true;
} else if (Constructor->isMoveConstructor()) {
data().UserDeclaredMoveConstructor = true;
data().DeclaredMoveConstructor = true;
@ -632,9 +597,6 @@ NotASpecialMember:;
// user-provided [...]
if (UserProvided)
data().HasTrivialMoveConstructor = false;
if (Constructor->isConstexpr())
data().HasConstexprMoveConstructor = true;
}
}
if (Constructor->isConstexpr() && !Constructor->isCopyOrMoveConstructor()) {
@ -676,18 +638,8 @@ NotASpecialMember:;
// C++11 [class.dtor]p5:
// A destructor is trivial if it is not user-provided and if
// -- the destructor is not virtual.
if (DD->isUserProvided() || DD->isVirtual()) {
if (DD->isUserProvided() || DD->isVirtual())
data().HasTrivialDestructor = false;
// C++11 [dcl.constexpr]p1:
// The constexpr specifier shall be applied only to [...] the
// declaration of a static data member of a literal type.
// C++11 [basic.types]p10:
// A type is a literal type if it is [...] a class type that [...] has
// a trivial destructor.
data().DefaultedDefaultConstructorIsConstexpr = false;
data().DefaultedCopyConstructorIsConstexpr = false;
data().DefaultedMoveConstructorIsConstexpr = false;
}
return;
}
@ -939,27 +891,11 @@ NotASpecialMember:;
// The standard requires any in-class initializer to be a constant
// expression. We consider this to be a defect.
data().DefaultedDefaultConstructorIsConstexpr = false;
if (!FieldRec->hasConstexprCopyConstructor())
data().DefaultedCopyConstructorIsConstexpr = false;
if (FieldRec->hasDeclaredMoveConstructor() ||
FieldRec->needsImplicitMoveConstructor())
// FIXME: If the implicit move constructor generated for the member's
// class would be ill-formed, the implicit move constructor generated
// for this class calls the member's copy constructor.
data().DefaultedMoveConstructorIsConstexpr &=
FieldRec->hasConstexprMoveConstructor();
else if (!FieldRec->hasConstexprCopyConstructor())
data().DefaultedMoveConstructorIsConstexpr = false;
}
} else {
// Base element type of field is a non-class type.
if (!T->isLiteralType()) {
data().DefaultedDefaultConstructorIsConstexpr = false;
data().DefaultedCopyConstructorIsConstexpr = false;
data().DefaultedMoveConstructorIsConstexpr = false;
} else if (!Field->hasInClassInitializer() && !isUnion())
if (!T->isLiteralType() ||
(!Field->hasInClassInitializer() && !isUnion()))
data().DefaultedDefaultConstructorIsConstexpr = false;
}

40
clang/lib/Sema/SemaDeclCXX.cpp
View File

@ -3897,8 +3897,17 @@ static bool defaultedSpecialMemberIsConstexpr(Sema &S, CXXRecordDecl *ClassDecl,
// In the definition of a constexpr constructor [...]
switch (CSM) {
case Sema::CXXDefaultConstructor:
// Since default constructor lookup is essentially trivial (and cannot
// involve, for instance, template instantiation), we compute whether a
// defaulted default constructor is constexpr directly within CXXRecordDecl.
//
// This is important for performance; we need to know whether the default
// constructor is constexpr to determine whether the type is a literal type.
return ClassDecl->defaultedDefaultConstructorIsConstexpr();
case Sema::CXXCopyConstructor:
case Sema::CXXMoveConstructor:
// For copy or move constructors, we need to perform overload resolution.
break;
case Sema::CXXCopyAssignment:
@ -3911,11 +3920,12 @@ static bool defaultedSpecialMemberIsConstexpr(Sema &S, CXXRecordDecl *ClassDecl,
// -- if the class is a non-empty union, or for each non-empty anonymous
// union member of a non-union class, exactly one non-static data member
// shall be initialized; [DR1359]
//
// If we squint, this is guaranteed, since exactly one non-static data member
// will be initialized (if the constructor isn't deleted), we just don't know
// which one.
if (ClassDecl->isUnion())
// FIXME: In the default constructor case, we should check that the
// in-class initializer is actually a constant expression.
return CSM != Sema::CXXDefaultConstructor ||
ClassDecl->hasInClassInitializer();
return true;
// -- the class shall not have any virtual base classes;
if (ClassDecl->getNumVBases())
@ -3943,29 +3953,11 @@ static bool defaultedSpecialMemberIsConstexpr(Sema &S, CXXRecordDecl *ClassDecl,
F != FEnd; ++F) {
if (F->isInvalidDecl())
continue;
if (CSM == Sema::CXXDefaultConstructor && F->hasInClassInitializer()) {
// -- every assignment-expression that is an initializer-clause appearing
// directly or indirectly within a brace-or-equal-initializer for a
// non-static data member [...] shall be a constant expression;
//
// We consider this bullet to be a defect, since it results in this type
// having a non-constexpr default constructor:
// struct S {
// int a = 0;
// int b = a;
// };
// FIXME: We should still check that the constructor selected for this
// initialization (if any) is constexpr.
} else if (const RecordType *RecordTy =
S.Context.getBaseElementType(F->getType())->
getAs<RecordType>()) {
if (const RecordType *RecordTy =
S.Context.getBaseElementType(F->getType())->getAs<RecordType>()) {
CXXRecordDecl *FieldRecDecl = cast<CXXRecordDecl>(RecordTy->getDecl());
if (!specialMemberIsConstexpr(S, FieldRecDecl, CSM, ConstArg))
return false;
} else if (CSM == Sema::CXXDefaultConstructor) {
// No in-class initializer, and not a class type. This member isn't going
// to be initialized.
return false;
}
}

4
clang/lib/Serialization/ASTReaderDecl.cpp
View File

@ -1094,11 +1094,7 @@ void ASTDeclReader::ReadCXXDefinitionData(
Data.HasTrivialDefaultConstructor = Record[Idx++];
Data.HasConstexprNonCopyMoveConstructor = Record[Idx++];
Data.DefaultedDefaultConstructorIsConstexpr = Record[Idx++];
Data.DefaultedCopyConstructorIsConstexpr = Record[Idx++];
Data.DefaultedMoveConstructorIsConstexpr = Record[Idx++];
Data.HasConstexprDefaultConstructor = Record[Idx++];
Data.HasConstexprCopyConstructor = Record[Idx++];
Data.HasConstexprMoveConstructor = Record[Idx++];
Data.HasTrivialCopyConstructor = Record[Idx++];
Data.HasTrivialMoveConstructor = Record[Idx++];
Data.HasTrivialCopyAssignment = Record[Idx++];

4
clang/lib/Serialization/ASTWriter.cpp
View File

@ -4313,11 +4313,7 @@ void ASTWriter::AddCXXDefinitionData(const CXXRecordDecl *D, RecordDataImpl &Rec
Record.push_back(Data.HasTrivialDefaultConstructor);
Record.push_back(Data.HasConstexprNonCopyMoveConstructor);
Record.push_back(Data.DefaultedDefaultConstructorIsConstexpr);
Record.push_back(Data.DefaultedCopyConstructorIsConstexpr);
Record.push_back(Data.DefaultedMoveConstructorIsConstexpr);
Record.push_back(Data.HasConstexprDefaultConstructor);
Record.push_back(Data.HasConstexprCopyConstructor);
Record.push_back(Data.HasConstexprMoveConstructor);
Record.push_back(Data.HasTrivialCopyConstructor);
Record.push_back(Data.HasTrivialMoveConstructor);
Record.push_back(Data.HasTrivialCopyAssignment);