MS ABI: Consider alignment attributes on typedefs for layout
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
diff --git a/clang/lib/AST/ASTContext.cpp b/clang/lib/AST/ASTContext.cpp
index bccdae9..c7685e4 100644
--- a/clang/lib/AST/ASTContext.cpp
+++ b/clang/lib/AST/ASTContext.cpp
@@ -1413,9 +1413,9 @@
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 @@
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 @@
/// 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 @@
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 @@
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 @@
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 @@
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 @@
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 @@
}
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 @@
/// 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 @@
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;