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MS ABI: Consider alignment attributes on typedefs for layout

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The MS ABI has a notion of 'required alignment' for fields; this
alignment supercedes pragma pack directives.

MSVC takes into account alignment attributes on typedefs when
determining whether or not a field has a certain required alignment.

Do the same in clang by tracking whether or not we saw such an attribute
when calculating the type's bitwidth and alignment.

This fixes PR20418.

Reviewers: rnk

Differential Revision: http://reviews.llvm.org/D4714

llvm-svn: 214274
This commit is contained in:
David Majnemer
2014-07-30 01:30:47 +00:00
parent 9dcc254a47
commit 34b5749989
7 changed files with 204 additions and 84 deletions
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41
clang/include/clang/AST/ASTContext.h
View File

@@ -74,6 +74,15 @@ namespace clang {
class FullComment;
}
struct TypeInfo {
uint64_t Width;
unsigned Align;
bool AlignIsRequired : 1;
TypeInfo() : Width(0), Align(0), AlignIsRequired(false) {}
TypeInfo(uint64_t Width, unsigned Align, bool AlignIsRequired)
: Width(Width), Align(Align), AlignIsRequired(AlignIsRequired) {}
};
/// \brief Holds long-lived AST nodes (such as types and decls) that can be
/// referred to throughout the semantic analysis of a file.
class ASTContext : public RefCountedBase<ASTContext> {
@@ -144,8 +153,7 @@ class ASTContext : public RefCountedBase<ASTContext> {
ObjCLayouts;
/// \brief A cache from types to size and alignment information.
typedef llvm::DenseMap<const Type*,
std::pair<uint64_t, unsigned> > TypeInfoMap;
typedef llvm::DenseMap<const Type *, struct TypeInfo> TypeInfoMap;
mutable TypeInfoMap MemoizedTypeInfo;
/// \brief A cache mapping from CXXRecordDecls to key functions.
@@ -1581,7 +1589,7 @@ public:
private:
CanQualType getFromTargetType(unsigned Type) const;
std::pair<uint64_t, unsigned> getTypeInfoImpl(const Type *T) const;
TypeInfo getTypeInfoImpl(const Type *T) const;
//===--------------------------------------------------------------------===//
// Type Predicates.
@@ -1614,18 +1622,12 @@ public:
const llvm::fltSemantics &getFloatTypeSemantics(QualType T) const;
/// \brief Get the size and alignment of the specified complete type in bits.
std::pair<uint64_t, unsigned> getTypeInfo(const Type *T) const;
std::pair<uint64_t, unsigned> getTypeInfo(QualType T) const {
return getTypeInfo(T.getTypePtr());
}
TypeInfo getTypeInfo(const Type *T) const;
TypeInfo getTypeInfo(QualType T) const { return getTypeInfo(T.getTypePtr()); }
/// \brief Return the size of the specified (complete) type \p T, in bits.
uint64_t getTypeSize(QualType T) const {
return getTypeInfo(T).first;
}
uint64_t getTypeSize(const Type *T) const {
return getTypeInfo(T).first;
}
uint64_t getTypeSize(QualType T) const { return getTypeInfo(T).Width; }
uint64_t getTypeSize(const Type *T) const { return getTypeInfo(T).Width; }
/// \brief Return the size of the character type, in bits.
uint64_t getCharWidth() const {
@@ -1645,12 +1647,8 @@ public:
/// \brief Return the ABI-specified alignment of a (complete) type \p T, in
/// bits.
unsigned getTypeAlign(QualType T) const {
return getTypeInfo(T).second;
}
unsigned getTypeAlign(const Type *T) const {
return getTypeInfo(T).second;
}
unsigned getTypeAlign(QualType T) const { return getTypeInfo(T).Align; }
unsigned getTypeAlign(const Type *T) const { return getTypeInfo(T).Align; }
/// \brief Return the ABI-specified alignment of a (complete) type \p T, in
/// characters.
@@ -1664,6 +1662,11 @@ public:
std::pair<CharUnits, CharUnits> getTypeInfoInChars(const Type *T) const;
std::pair<CharUnits, CharUnits> getTypeInfoInChars(QualType T) const;
/// \brief Determine if the alignment the type has was required using an
/// alignment attribute.
bool isAlignmentRequired(const Type *T) const;
bool isAlignmentRequired(QualType T) const;
/// \brief Return the "preferred" alignment of the specified type \p T for
/// the current target, in bits.
///

81
clang/lib/AST/ASTContext.cpp
View File

@@ -1413,9 +1413,9 @@ std::pair<CharUnits, CharUnits>
ASTContext::getTypeInfoInChars(const Type *T) const {
if (const ConstantArrayType *CAT = dyn_cast<ConstantArrayType>(T))
return getConstantArrayInfoInChars(*this, CAT);
std::pair<uint64_t, unsigned> Info = getTypeInfo(T);
return std::make_pair(toCharUnitsFromBits(Info.first),
toCharUnitsFromBits(Info.second));
TypeInfo Info = getTypeInfo(T);
return std::make_pair(toCharUnitsFromBits(Info.Width),
toCharUnitsFromBits(Info.Align));
}
std::pair<CharUnits, CharUnits>
@@ -1423,14 +1423,20 @@ ASTContext::getTypeInfoInChars(QualType T) const {
return getTypeInfoInChars(T.getTypePtr());
}
std::pair<uint64_t, unsigned> ASTContext::getTypeInfo(const Type *T) const {
TypeInfoMap::iterator it = MemoizedTypeInfo.find(T);
if (it != MemoizedTypeInfo.end())
return it->second;
bool ASTContext::isAlignmentRequired(const Type *T) const {
return getTypeInfo(T).AlignIsRequired;
}
std::pair<uint64_t, unsigned> Info = getTypeInfoImpl(T);
MemoizedTypeInfo.insert(std::make_pair(T, Info));
return Info;
bool ASTContext::isAlignmentRequired(QualType T) const {
return isAlignmentRequired(T.getTypePtr());
}
TypeInfo ASTContext::getTypeInfo(const Type *T) const {
TypeInfo &TI = MemoizedTypeInfo[T];
if (!TI.Align)
TI = getTypeInfoImpl(T);
return TI;
}
/// getTypeInfoImpl - Return the size of the specified type, in bits. This
@@ -1439,10 +1445,10 @@ std::pair<uint64_t, unsigned> ASTContext::getTypeInfo(const Type *T) const {
/// FIXME: Pointers into different addr spaces could have different sizes and
/// alignment requirements: getPointerInfo should take an AddrSpace, this
/// should take a QualType, &c.
std::pair<uint64_t, unsigned>
ASTContext::getTypeInfoImpl(const Type *T) const {
uint64_t Width=0;
unsigned Align=8;
TypeInfo ASTContext::getTypeInfoImpl(const Type *T) const {
uint64_t Width = 0;
unsigned Align = 8;
bool AlignIsRequired = false;
switch (T->getTypeClass()) {
#define TYPE(Class, Base)
#define ABSTRACT_TYPE(Class, Base)
@@ -1471,12 +1477,12 @@ ASTContext::getTypeInfoImpl(const Type *T) const {
case Type::ConstantArray: {
const ConstantArrayType *CAT = cast<ConstantArrayType>(T);
std::pair<uint64_t, unsigned> EltInfo = getTypeInfo(CAT->getElementType());
TypeInfo EltInfo = getTypeInfo(CAT->getElementType());
uint64_t Size = CAT->getSize().getZExtValue();
assert((Size == 0 || EltInfo.first <= (uint64_t)(-1)/Size) &&
assert((Size == 0 || EltInfo.Width <= (uint64_t)(-1) / Size) &&
"Overflow in array type bit size evaluation");
Width = EltInfo.first*Size;
Align = EltInfo.second;
Width = EltInfo.Width * Size;
Align = EltInfo.Align;
if (!getTargetInfo().getCXXABI().isMicrosoft() ||
getTargetInfo().getPointerWidth(0) == 64)
Width = llvm::RoundUpToAlignment(Width, Align);
@@ -1485,8 +1491,8 @@ ASTContext::getTypeInfoImpl(const Type *T) const {
case Type::ExtVector:
case Type::Vector: {
const VectorType *VT = cast<VectorType>(T);
std::pair<uint64_t, unsigned> EltInfo = getTypeInfo(VT->getElementType());
Width = EltInfo.first*VT->getNumElements();
TypeInfo EltInfo = getTypeInfo(VT->getElementType());
Width = EltInfo.Width * VT->getNumElements();
Align = Width;
// If the alignment is not a power of 2, round up to the next power of 2.
// This happens for non-power-of-2 length vectors.
@@ -1638,10 +1644,9 @@ ASTContext::getTypeInfoImpl(const Type *T) const {
case Type::Complex: {
// Complex types have the same alignment as their elements, but twice the
// size.
std::pair<uint64_t, unsigned> EltInfo =
getTypeInfo(cast<ComplexType>(T)->getElementType());
Width = EltInfo.first*2;
Align = EltInfo.second;
TypeInfo EltInfo = getTypeInfo(cast<ComplexType>(T)->getElementType());
Width = EltInfo.Width * 2;
Align = EltInfo.Align;
break;
}
case Type::ObjCObject:
@@ -1692,16 +1697,16 @@ ASTContext::getTypeInfoImpl(const Type *T) const {
case Type::Typedef: {
const TypedefNameDecl *Typedef = cast<TypedefType>(T)->getDecl();
std::pair<uint64_t, unsigned> Info
= getTypeInfo(Typedef->getUnderlyingType().getTypePtr());
TypeInfo Info = getTypeInfo(Typedef->getUnderlyingType().getTypePtr());
// If the typedef has an aligned attribute on it, it overrides any computed
// alignment we have. This violates the GCC documentation (which says that
// attribute(aligned) can only round up) but matches its implementation.
if (unsigned AttrAlign = Typedef->getMaxAlignment())
if (unsigned AttrAlign = Typedef->getMaxAlignment()) {
Align = AttrAlign;
else
Align = Info.second;
Width = Info.first;
AlignIsRequired = true;
} else
Align = Info.Align;
Width = Info.Width;
break;
}
@@ -1714,10 +1719,9 @@ ASTContext::getTypeInfoImpl(const Type *T) const {
case Type::Atomic: {
// Start with the base type information.
std::pair<uint64_t, unsigned> Info
= getTypeInfo(cast<AtomicType>(T)->getValueType());
Width = Info.first;
Align = Info.second;
TypeInfo Info = getTypeInfo(cast<AtomicType>(T)->getValueType());
Width = Info.Width;
Align = Info.Align;
// If the size of the type doesn't exceed the platform's max
// atomic promotion width, make the size and alignment more
@@ -1735,7 +1739,7 @@ ASTContext::getTypeInfoImpl(const Type *T) const {
}
assert(llvm::isPowerOf2_32(Align) && "Alignment must be power of 2");
return std::make_pair(Width, Align);
return TypeInfo(Width, Align, AlignIsRequired);
}
/// toCharUnitsFromBits - Convert a size in bits to a size in characters.
@@ -1771,13 +1775,12 @@ CharUnits ASTContext::getTypeAlignInChars(const Type *T) const {
/// alignment in cases where it is beneficial for performance to overalign
/// a data type.
unsigned ASTContext::getPreferredTypeAlign(const Type *T) const {
unsigned ABIAlign = getTypeAlign(T);
TypeInfo TI = getTypeInfo(T);
unsigned ABIAlign = TI.Align;
if (Target->getTriple().getArch() == llvm::Triple::xcore)
return ABIAlign; // Never overalign on XCore.
const TypedefType *TT = T->getAs<TypedefType>();
// Double and long long should be naturally aligned if possible.
T = T->getBaseElementTypeUnsafe();
if (const ComplexType *CT = T->getAs<ComplexType>())
@@ -1787,7 +1790,7 @@ unsigned ASTContext::getPreferredTypeAlign(const Type *T) const {
T->isSpecificBuiltinType(BuiltinType::ULongLong))
// Don't increase the alignment if an alignment attribute was specified on a
// typedef declaration.
if (!TT || !TT->getDecl()->getMaxAlignment())
if (!TI.AlignIsRequired)
return std::max(ABIAlign, (unsigned)getTypeSize(T));
return ABIAlign;

18
clang/lib/AST/RecordLayoutBuilder.cpp
View File

@@ -1413,9 +1413,9 @@ void RecordLayoutBuilder::LayoutWideBitField(uint64_t FieldSize,
void RecordLayoutBuilder::LayoutBitField(const FieldDecl *D) {
bool FieldPacked = Packed || D->hasAttr<PackedAttr>();
uint64_t FieldSize = D->getBitWidthValue(Context);
std::pair<uint64_t, unsigned> FieldInfo = Context.getTypeInfo(D->getType());
uint64_t TypeSize = FieldInfo.first;
unsigned FieldAlign = FieldInfo.second;
TypeInfo FieldInfo = Context.getTypeInfo(D->getType());
uint64_t TypeSize = FieldInfo.Width;
unsigned FieldAlign = FieldInfo.Align;
// UnfilledBitsInLastUnit is the difference between the end of the
// last allocated bitfield (i.e. the first bit offset available for
@@ -2260,12 +2260,18 @@ MicrosoftRecordLayoutBuilder::getAdjustedElementInfo(
MicrosoftRecordLayoutBuilder::ElementInfo
MicrosoftRecordLayoutBuilder::getAdjustedElementInfo(
const FieldDecl *FD) {
// Get the alignment of the field type's natural alignment, ignore any
// alignment attributes.
ElementInfo Info;
std::tie(Info.Size, Info.Alignment) =
Context.getTypeInfoInChars(FD->getType());
// Respect align attributes.
CharUnits FieldRequiredAlignment =
Context.getTypeInfoInChars(FD->getType()->getUnqualifiedDesugaredType());
// Respect align attributes on the field.
CharUnits FieldRequiredAlignment =
Context.toCharUnitsFromBits(FD->getMaxAlignment());
// Respect align attributes on the type.
if (Context.isAlignmentRequired(FD->getType()))
FieldRequiredAlignment = std::max(
Context.getTypeAlignInChars(FD->getType()), FieldRequiredAlignment);
// Respect attributes applied to subobjects of the field.
if (FD->isBitField())
// For some reason __declspec align impacts alignment rather than required

18
clang/lib/CodeGen/CGAtomic.cpp
View File

@@ -46,17 +46,21 @@ namespace {
ASTContext &C = CGF.getContext();
uint64_t valueAlignInBits;
std::tie(ValueSizeInBits, valueAlignInBits) = C.getTypeInfo(ValueTy);
uint64_t ValueAlignInBits;
uint64_t AtomicAlignInBits;
TypeInfo ValueTI = C.getTypeInfo(ValueTy);
ValueSizeInBits = ValueTI.Width;
ValueAlignInBits = ValueTI.Align;
uint64_t atomicAlignInBits;
std::tie(AtomicSizeInBits, atomicAlignInBits) = C.getTypeInfo(AtomicTy);
TypeInfo AtomicTI = C.getTypeInfo(AtomicTy);
AtomicSizeInBits = AtomicTI.Width;
AtomicAlignInBits = AtomicTI.Align;
assert(ValueSizeInBits <= AtomicSizeInBits);
assert(valueAlignInBits <= atomicAlignInBits);
assert(ValueAlignInBits <= AtomicAlignInBits);
AtomicAlign = C.toCharUnitsFromBits(atomicAlignInBits);
ValueAlign = C.toCharUnitsFromBits(valueAlignInBits);
AtomicAlign = C.toCharUnitsFromBits(AtomicAlignInBits);
ValueAlign = C.toCharUnitsFromBits(ValueAlignInBits);
if (lvalue.getAlignment().isZero())
lvalue.setAlignment(AtomicAlign);

24
clang/lib/CodeGen/CGDebugInfo.cpp
View File

@@ -803,13 +803,15 @@ llvm::DIType CGDebugInfo::createFieldType(StringRef name,
llvm::DIFile file = getOrCreateFile(loc);
unsigned line = getLineNumber(loc);
uint64_t sizeInBits = 0;
unsigned alignInBits = 0;
uint64_t SizeInBits = 0;
unsigned AlignInBits = 0;
if (!type->isIncompleteArrayType()) {
std::tie(sizeInBits, alignInBits) = CGM.getContext().getTypeInfo(type);
TypeInfo TI = CGM.getContext().getTypeInfo(type);
SizeInBits = TI.Width;
AlignInBits = TI.Align;
if (sizeInBitsOverride)
sizeInBits = sizeInBitsOverride;
SizeInBits = sizeInBitsOverride;
}
unsigned flags = 0;
@@ -818,8 +820,8 @@ llvm::DIType CGDebugInfo::createFieldType(StringRef name,
else if (AS == clang::AS_protected)
flags |= llvm::DIDescriptor::FlagProtected;
return DBuilder.createMemberType(scope, name, file, line, sizeInBits,
alignInBits, offsetInBits, flags, debugType);
return DBuilder.createMemberType(scope, name, file, line, SizeInBits,
AlignInBits, offsetInBits, flags, debugType);
}
/// CollectRecordLambdaFields - Helper for CollectRecordFields.
@@ -3030,15 +3032,15 @@ void CGDebugInfo::EmitDeclareOfBlockLiteralArgVariable(const CGBlockInfo &block,
llvm::DIType fieldType;
if (capture->isByRef()) {
std::pair<uint64_t,unsigned> ptrInfo = C.getTypeInfo(C.VoidPtrTy);
TypeInfo PtrInfo = C.getTypeInfo(C.VoidPtrTy);
// FIXME: this creates a second copy of this type!
uint64_t xoffset;
fieldType = EmitTypeForVarWithBlocksAttr(variable, &xoffset);
fieldType = DBuilder.createPointerType(fieldType, ptrInfo.first);
fieldType = DBuilder.createMemberType(tunit, name, tunit, line,
ptrInfo.first, ptrInfo.second,
offsetInBits, 0, fieldType);
fieldType = DBuilder.createPointerType(fieldType, PtrInfo.Width);
fieldType =
DBuilder.createMemberType(tunit, name, tunit, line, PtrInfo.Width,
PtrInfo.Align, offsetInBits, 0, fieldType);
} else {
fieldType = createFieldType(name, variable->getType(), 0,
loc, AS_public, offsetInBits, tunit, tunit);

15
clang/lib/Sema/SemaDeclObjC.cpp
View File

@@ -2107,7 +2107,12 @@ static bool matchTypes(ASTContext &Context, Sema::MethodMatchStrategy strategy,
// validate the basic, low-level compatibility of the two types.
// As a minimum, require the sizes and alignments to match.
if (Context.getTypeInfo(left) != Context.getTypeInfo(right))
TypeInfo LeftTI = Context.getTypeInfo(left);
TypeInfo RightTI = Context.getTypeInfo(right);
if (LeftTI.Width != RightTI.Width)
return false;
if (LeftTI.Align != RightTI.Align)
return false;
// Consider all the kinds of non-dependent canonical types:
@@ -2159,7 +2164,13 @@ static bool tryMatchRecordTypes(ASTContext &Context,
return false;
// Require size and alignment to match.
if (Context.getTypeInfo(lt) != Context.getTypeInfo(rt)) return false;
TypeInfo LeftTI = Context.getTypeInfo(lt);
TypeInfo RightTI = Context.getTypeInfo(rt);
if (LeftTI.Width != RightTI.Width)
return false;
if (LeftTI.Align != RightTI.Align)
return false;
// Require fields to match.
RecordDecl::field_iterator li = left->field_begin(), le = left->field_end();

91
clang/test/Layout/ms-x86-pack-and-align.cpp
View File

@@ -652,7 +652,94 @@ struct OD : OC {};
// CHECK-X64-NEXT: | [sizeof=12, align=1
// CHECK-X64-NEXT: | nvsize=8, nvalign=1]
struct __declspec(align(4)) PA {
int c;
};
typedef __declspec(align(8)) PA PB;
#pragma pack(push, 1)
struct PC {
char a;
PB x;
};
#pragma pack(pop)
// CHECK: *** Dumping AST Record Layout
// CHECK: 0 | struct PC
// CHECK-NEXT: 0 | char a
// CHECK-NEXT: 8 | struct PA x
// CHECK-NEXT: 8 | int c
// CHECK-NEXT: | [sizeof=4, align=4
// CHECK-NEXT: | nvsize=4, nvalign=4]
// CHECK-NEXT: | [sizeof=16, align=8
// CHECK-NEXT: | nvsize=12, nvalign=8]
// CHECK-X64: *** Dumping AST Record Layout
// CHECK-X64: 0 | struct PC
// CHECK-X64-NEXT: 0 | char a
// CHECK-X64-NEXT: 8 | struct PA x
// CHECK-X64-NEXT: 8 | int c
// CHECK-X64-NEXT: | [sizeof=4, align=4
// CHECK-X64-NEXT: | nvsize=4, nvalign=4]
// CHECK-X64-NEXT: | [sizeof=16, align=8
// CHECK-X64-NEXT: | nvsize=12, nvalign=8]
typedef int __declspec(align(2)) QA;
#pragma pack(push, 1)
struct QB {
char a;
QA b;
};
#pragma pack(pop)
// CHECK: *** Dumping AST Record Layout
// CHECK-NEXT: 0 | struct QB
// CHECK-NEXT: 0 | char a
// CHECK-NEXT: 2 | QA b
// CHECK-NEXT: | [sizeof=6, align=2
// CHECK-NEXT: | nvsize=6, nvalign=2]
// CHECK-X64: *** Dumping AST Record Layout
// CHECK-X64-NEXT: 0 | struct QB
// CHECK-X64-NEXT: 0 | char a
// CHECK-X64-NEXT: 2 | QA b
// CHECK-X64-NEXT: | [sizeof=6, align=2
// CHECK-X64-NEXT: | nvsize=6, nvalign=2]
struct QC {
char a;
QA b;
};
// CHECK: *** Dumping AST Record Layout
// CHECK-NEXT: 0 | struct QC
// CHECK-NEXT: 0 | char a
// CHECK-NEXT: 4 | QA b
// CHECK-NEXT: | [sizeof=8, align=4
// CHECK-NEXT: | nvsize=8, nvalign=4]
// CHECK-X64: *** Dumping AST Record Layout
// CHECK-X64-NEXT: 0 | struct QC
// CHECK-X64-NEXT: 0 | char a
// CHECK-X64-NEXT: 4 | QA b
// CHECK-X64-NEXT: | [sizeof=8, align=4
// CHECK-X64-NEXT: | nvsize=8, nvalign=4]
struct QD {
char a;
QA b : 3;
};
// CHECK: *** Dumping AST Record Layout
// CHECK-NEXT: 0 | struct QD
// CHECK-NEXT: 0 | char a
// CHECK-NEXT: 4 | QA b
// CHECK-NEXT: | [sizeof=8, align=4
// CHECK-NEXT: | nvsize=8, nvalign=4]
// CHECK-X64: *** Dumping AST Record Layout
// CHECK-X64-NEXT: 0 | struct QD
// CHECK-X64-NEXT: 0 | char a
// CHECK-X64-NEXT: 4 | QA b
// CHECK-X64-NEXT: | [sizeof=8, align=4
// CHECK-X64-NEXT: | nvsize=8, nvalign=4]
int a[
sizeof(X)+
@@ -680,4 +767,8 @@ sizeof(RC)+
sizeof(RE)+
sizeof(ND)+
sizeof(OD)+
sizeof(PC)+
sizeof(QB)+
sizeof(QC)+
sizeof(QD)+
0];