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[ObjC++] Never pass structs that transitively contain __weak fields in
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registers.

This patch fixes a bug in r328731 that caused structs transitively
containing __weak fields to be passed in registers. The patch replaces
the flag RecordDecl::CanPassInRegisters with a 2-bit enum that indicates
whether the struct or structs containing the struct are forced to be
passed indirectly.

This reapplies r329617. r329617 didn't specify the underlying type for
enum ArgPassingKind, which caused regression tests to fail on a windows
bot.

rdar://problem/39194693

Differential Revision: https://reviews.llvm.org/D45384

llvm-svn: 329635
ahatanaka committed Apr 9, 2018
1 parent 3539c09 commit e6313ac
Showing 11 changed files with 102 additions and 47 deletions.
45 changes: 35 additions & 10 deletions clang/include/clang/AST/Decl.h
Original file line number Diff line number Diff line change
@@ -3541,6 +3541,31 @@ class EnumDecl : public TagDecl {
/// union Y { int A, B; }; // Has body with members A and B (FieldDecls).
/// This decl will be marked invalid if *any* members are invalid.
class RecordDecl : public TagDecl {
public:
/// Enum that represents the different ways arguments are passed to and
/// returned from function calls. This takes into account the target-specific
/// and version-specific rules along with the rules determined by the
/// language.
enum ArgPassingKind : unsigned {
/// The argument of this type can be passed directly in registers.
APK_CanPassInRegs,

/// The argument of this type cannot be passed directly in registers.
/// Records containing this type as a subobject are not forced to be passed
/// indirectly. This value is used only in C++. This value is required by
/// C++ because, in uncommon situations, it is possible for a class to have
/// only trivial copy/move constructors even when one of its subobjects has
/// a non-trivial copy/move constructor (if e.g. the corresponding copy/move
/// constructor in the derived class is deleted).
APK_CannotPassInRegs,

/// The argument of this type cannot be passed directly in registers.
/// Records containing this type as a subobject are forced to be passed
/// indirectly.
APK_CanNeverPassInRegs
};

private:
friend class DeclContext;

// FIXME: This can be packed into the bitfields in Decl.
@@ -3571,17 +3596,14 @@ class RecordDecl : public TagDecl {
bool NonTrivialToPrimitiveCopy : 1;
bool NonTrivialToPrimitiveDestroy : 1;

/// True if this class can be passed in a non-address-preserving fashion
/// (such as in registers).
/// This does not imply anything about how the ABI in use will actually
/// pass an object of this class.
bool CanPassInRegisters : 1;

/// Indicates whether this struct is destroyed in the callee. This flag is
/// meaningless when Microsoft ABI is used since parameters are always
/// destroyed in the callee.
bool ParamDestroyedInCallee : 1;

/// Represents the way this type is passed to a function.
ArgPassingKind ArgPassingRestrictions : 2;

protected:
RecordDecl(Kind DK, TagKind TK, const ASTContext &C, DeclContext *DC,
SourceLocation StartLoc, SourceLocation IdLoc,
@@ -3669,12 +3691,15 @@ class RecordDecl : public TagDecl {
/// it must have at least one trivial, non-deleted copy or move constructor.
/// FIXME: This should be set as part of completeDefinition.
bool canPassInRegisters() const {
return CanPassInRegisters;
return ArgPassingRestrictions == APK_CanPassInRegs;
}

ArgPassingKind getArgPassingRestrictions() const {
return ArgPassingRestrictions;
}

/// Set that we can pass this RecordDecl in registers.
void setCanPassInRegisters(bool CanPass) {
CanPassInRegisters = CanPass;
void setArgPassingRestrictions(ArgPassingKind Kind) {
ArgPassingRestrictions = Kind;
}

bool isParamDestroyedInCallee() const {
2 changes: 0 additions & 2 deletions clang/include/clang/AST/Type.h
Original file line number Diff line number Diff line change
@@ -1149,8 +1149,6 @@ class QualType {
/// source object is placed in an uninitialized state.
PrimitiveCopyKind isNonTrivialToPrimitiveDestructiveMove() const;

bool canPassInRegisters() const;

enum DestructionKind {
DK_none,
DK_cxx_destructor,
2 changes: 1 addition & 1 deletion clang/lib/AST/Decl.cpp
Original file line number Diff line number Diff line change
@@ -3956,7 +3956,7 @@ RecordDecl::RecordDecl(Kind DK, TagKind TK, const ASTContext &C,
LoadedFieldsFromExternalStorage(false),
NonTrivialToPrimitiveDefaultInitialize(false),
NonTrivialToPrimitiveCopy(false), NonTrivialToPrimitiveDestroy(false),
CanPassInRegisters(true), ParamDestroyedInCallee(false) {
ParamDestroyedInCallee(false), ArgPassingRestrictions(APK_CanPassInRegs) {
assert(classof(static_cast<Decl*>(this)) && "Invalid Kind!");
}

9 changes: 8 additions & 1 deletion clang/lib/AST/DeclCXX.cpp
Original file line number Diff line number Diff line change
@@ -421,6 +421,10 @@ CXXRecordDecl::setBases(CXXBaseSpecifier const * const *Bases,
if (BaseClassDecl->hasVolatileMember())
setHasVolatileMember(true);

if (BaseClassDecl->getArgPassingRestrictions() ==
RecordDecl::APK_CanNeverPassInRegs)
setArgPassingRestrictions(RecordDecl::APK_CanNeverPassInRegs);

// Keep track of the presence of mutable fields.
if (BaseClassDecl->hasMutableFields()) {
data().HasMutableFields = true;
@@ -950,7 +954,7 @@ void CXXRecordDecl::addedMember(Decl *D) {

// Structs with __weak fields should never be passed directly.
if (LT == Qualifiers::OCL_Weak)
setCanPassInRegisters(false);
setArgPassingRestrictions(RecordDecl::APK_CanNeverPassInRegs);

Data.HasIrrelevantDestructor = false;
} else if (!Context.getLangOpts().ObjCAutoRefCount) {
@@ -1117,6 +1121,9 @@ void CXXRecordDecl::addedMember(Decl *D) {
setHasObjectMember(true);
if (FieldRec->hasVolatileMember())
setHasVolatileMember(true);
if (FieldRec->getArgPassingRestrictions() ==
RecordDecl::APK_CanNeverPassInRegs)
setArgPassingRestrictions(RecordDecl::APK_CanNeverPassInRegs);

// C++0x [class]p7:
// A standard-layout class is a class that:
11 changes: 0 additions & 11 deletions clang/lib/AST/Type.cpp
Original file line number Diff line number Diff line change
@@ -2239,17 +2239,6 @@ QualType::isNonTrivialToPrimitiveDestructiveMove() const {
return isNonTrivialToPrimitiveCopy();
}

bool QualType::canPassInRegisters() const {
if (const auto *RT =
getTypePtr()->getBaseElementTypeUnsafe()->getAs<RecordType>())
return RT->getDecl()->canPassInRegisters();

if (getQualifiers().getObjCLifetime() == Qualifiers::OCL_Weak)
return false;

return true;
}

bool Type::isLiteralType(const ASTContext &Ctx) const {
if (isDependentType())
return false;
9 changes: 7 additions & 2 deletions clang/lib/Sema/SemaDecl.cpp
Original file line number Diff line number Diff line change
@@ -15465,8 +15465,13 @@ void Sema::ActOnFields(Scope *S, SourceLocation RecLoc, Decl *EnclosingDecl,
Record->setNonTrivialToPrimitiveDestroy(true);
Record->setParamDestroyedInCallee(true);
}
if (!FT.canPassInRegisters())
Record->setCanPassInRegisters(false);

if (const auto *RT = FT->getAs<RecordType>()) {
if (RT->getDecl()->getArgPassingRestrictions() ==
RecordDecl::APK_CanNeverPassInRegs)
Record->setArgPassingRestrictions(RecordDecl::APK_CanNeverPassInRegs);
} else if (FT.getQualifiers().getObjCLifetime() == Qualifiers::OCL_Weak)
Record->setArgPassingRestrictions(RecordDecl::APK_CanNeverPassInRegs);
}

if (Record && FD->getType().isVolatileQualified())
30 changes: 15 additions & 15 deletions clang/lib/Sema/SemaDeclCXX.cpp
Original file line number Diff line number Diff line change
@@ -5847,20 +5847,20 @@ static bool paramCanBeDestroyedInCallee(Sema &S, CXXRecordDecl *D,
return HasNonDeletedCopyOrMove;
}

static bool computeCanPassInRegister(bool DestroyedInCallee,
const CXXRecordDecl *RD,
TargetInfo::CallingConvKind CCK,
Sema &S) {
static RecordDecl::ArgPassingKind
computeArgPassingRestrictions(bool DestroyedInCallee, const CXXRecordDecl *RD,
TargetInfo::CallingConvKind CCK, Sema &S) {
if (RD->isDependentType() || RD->isInvalidDecl())
return true;
return RecordDecl::APK_CanPassInRegs;

// The param cannot be passed in registers if CanPassInRegisters is already
// set to false.
if (!RD->canPassInRegisters())
return false;
// The param cannot be passed in registers if ArgPassingRestrictions is set to
// APK_CanNeverPassInRegs.
if (RD->getArgPassingRestrictions() == RecordDecl::APK_CanNeverPassInRegs)
return RecordDecl::APK_CanNeverPassInRegs;

if (CCK != TargetInfo::CCK_MicrosoftX86_64)
return DestroyedInCallee;
return DestroyedInCallee ? RecordDecl::APK_CanPassInRegs
: RecordDecl::APK_CannotPassInRegs;

bool CopyCtorIsTrivial = false, CopyCtorIsTrivialForCall = false;
bool DtorIsTrivialForCall = false;
@@ -5900,7 +5900,7 @@ static bool computeCanPassInRegister(bool DestroyedInCallee,

// If the copy ctor and dtor are both trivial-for-calls, pass direct.
if (CopyCtorIsTrivialForCall && DtorIsTrivialForCall)
return true;
return RecordDecl::APK_CanPassInRegs;

// If a class has a destructor, we'd really like to pass it indirectly
// because it allows us to elide copies. Unfortunately, MSVC makes that
@@ -5914,8 +5914,8 @@ static bool computeCanPassInRegister(bool DestroyedInCallee,
// passed in registers, which is non-conforming.
if (CopyCtorIsTrivial &&
S.getASTContext().getTypeSize(RD->getTypeForDecl()) <= 64)
return true;
return false;
return RecordDecl::APK_CanPassInRegs;
return RecordDecl::APK_CannotPassInRegs;
}

/// \brief Perform semantic checks on a class definition that has been
@@ -6090,8 +6090,8 @@ void Sema::CheckCompletedCXXClass(CXXRecordDecl *Record) {
if (Record->hasNonTrivialDestructor())
Record->setParamDestroyedInCallee(DestroyedInCallee);

Record->setCanPassInRegisters(
computeCanPassInRegister(DestroyedInCallee, Record, CCK, *this));
Record->setArgPassingRestrictions(
computeArgPassingRestrictions(DestroyedInCallee, Record, CCK, *this));
}

/// Look up the special member function that would be called by a special
5 changes: 3 additions & 2 deletions clang/lib/Serialization/ASTReaderDecl.cpp
Original file line number Diff line number Diff line change
@@ -742,8 +742,8 @@ ASTDeclReader::VisitRecordDeclImpl(RecordDecl *RD) {
RD->setNonTrivialToPrimitiveDefaultInitialize(Record.readInt());
RD->setNonTrivialToPrimitiveCopy(Record.readInt());
RD->setNonTrivialToPrimitiveDestroy(Record.readInt());
RD->setCanPassInRegisters(Record.readInt());
RD->setParamDestroyedInCallee(Record.readInt());
RD->setArgPassingRestrictions((RecordDecl::ArgPassingKind)Record.readInt());
return Redecl;
}

@@ -4114,8 +4114,9 @@ void ASTDeclReader::UpdateDecl(Decl *D,
bool HadRealDefinition =
OldDD && (OldDD->Definition != RD ||
!Reader.PendingFakeDefinitionData.count(OldDD));
RD->setCanPassInRegisters(Record.readInt());
RD->setParamDestroyedInCallee(Record.readInt());
RD->setArgPassingRestrictions(
(RecordDecl::ArgPassingKind)Record.readInt());
ReadCXXRecordDefinition(RD, /*Update*/true);

// Visible update is handled separately.
2 changes: 1 addition & 1 deletion clang/lib/Serialization/ASTWriter.cpp
Original file line number Diff line number Diff line change
@@ -5193,8 +5193,8 @@ void ASTWriter::WriteDeclUpdatesBlocks(RecordDataImpl &OffsetsRecord) {
case UPD_CXX_INSTANTIATED_CLASS_DEFINITION: {
auto *RD = cast<CXXRecordDecl>(D);
UpdatedDeclContexts.insert(RD->getPrimaryContext());
Record.push_back(RD->canPassInRegisters());
Record.push_back(RD->isParamDestroyedInCallee());
Record.push_back(RD->getArgPassingRestrictions());
Record.AddCXXDefinitionData(RD);
Record.AddOffset(WriteDeclContextLexicalBlock(
*Context, const_cast<CXXRecordDecl *>(RD)));
5 changes: 3 additions & 2 deletions clang/lib/Serialization/ASTWriterDecl.cpp
Original file line number Diff line number Diff line change
@@ -469,8 +469,8 @@ void ASTDeclWriter::VisitRecordDecl(RecordDecl *D) {
Record.push_back(D->isNonTrivialToPrimitiveDefaultInitialize());
Record.push_back(D->isNonTrivialToPrimitiveCopy());
Record.push_back(D->isNonTrivialToPrimitiveDestroy());
Record.push_back(D->canPassInRegisters());
Record.push_back(D->isParamDestroyedInCallee());
Record.push_back(D->getArgPassingRestrictions());

if (D->getDeclContext() == D->getLexicalDeclContext() &&
!D->hasAttrs() &&
@@ -1913,9 +1913,10 @@ void ASTWriter::WriteDeclAbbrevs() {
Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));
// isNonTrivialToPrimitiveDestroy
Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));
Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1)); // canPassInRegisters
// isParamDestroyedInCallee
Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));
// getArgPassingRestrictions
Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 2));

// DC
Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // LexicalOffset
29 changes: 29 additions & 0 deletions clang/test/CodeGenObjCXX/objc-struct-cxx-abi.mm
Original file line number Diff line number Diff line change
@@ -8,6 +8,8 @@
// pointer fields are passed directly.

// CHECK: %[[STRUCT_STRONGWEAK:.*]] = type { i8*, i8* }
// CHECK: %[[STRUCT_CONTAINSSTRONGWEAK:.*]] = type { %[[STRUCT_STRONGWEAK]] }
// CHECK: %[[STRUCT_DERIVEDSTRONGWEAK:.*]] = type { %[[STRUCT_STRONGWEAK]] }
// CHECK: %[[STRUCT_STRONG:.*]] = type { i8* }
// CHECK: %[[STRUCT_S:.*]] = type { i8* }
// CHECK: %[[STRUCT_CONTAINSNONTRIVIAL:.*]] = type { %{{.*}}, i8* }
@@ -21,6 +23,21 @@ struct __attribute__((trivial_abi)) StrongWeak {
__weak id fweak;
};

#ifdef TRIVIALABI
struct __attribute__((trivial_abi)) ContainsStrongWeak {
#else
struct ContainsStrongWeak {
#endif
StrongWeak sw;
};

#ifdef TRIVIALABI
struct __attribute__((trivial_abi)) DerivedStrongWeak : StrongWeak {
#else
struct DerivedStrongWeak : StrongWeak {
#endif
};

#ifdef TRIVIALABI
struct __attribute__((trivial_abi)) Strong {
#else
@@ -84,6 +101,18 @@ StrongWeak testReturnStrongWeak(StrongWeak *a) {
return *a;
}

// CHECK: define void @_Z27testParamContainsStrongWeak18ContainsStrongWeak(%[[STRUCT_CONTAINSSTRONGWEAK]]* %[[A:.*]])
// CHECK: call %[[STRUCT_CONTAINSSTRONGWEAK]]* @_ZN18ContainsStrongWeakD1Ev(%[[STRUCT_CONTAINSSTRONGWEAK]]* %[[A]])

void testParamContainsStrongWeak(ContainsStrongWeak a) {
}

// CHECK: define void @_Z26testParamDerivedStrongWeak17DerivedStrongWeak(%[[STRUCT_DERIVEDSTRONGWEAK]]* %[[A:.*]])
// CHECK: call %[[STRUCT_DERIVEDSTRONGWEAK]]* @_ZN17DerivedStrongWeakD1Ev(%[[STRUCT_DERIVEDSTRONGWEAK]]* %[[A]])

void testParamDerivedStrongWeak(DerivedStrongWeak a) {
}

// CHECK: define void @_Z15testParamStrong6Strong(i64 %[[A_COERCE:.*]])
// CHECK: %[[A:.*]] = alloca %[[STRUCT_STRONG]], align 8
// CHECK: %[[COERCE_DIVE:.*]] = getelementptr inbounds %[[STRUCT_STRONG]], %[[STRUCT_STRONG]]* %[[A]], i32 0, i32 0

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