void VBTableInfo::EmitVBTableDefinition(
CodeGenModule &CGM, const CXXRecordDecl *RD,
llvm::GlobalVariable::LinkageTypes Linkage) const {
assert(RD->getNumVBases() && ReusingBase->getNumVBases() &&
"should only emit vbtables for classes with vbtables");
const ASTRecordLayout &BaseLayout =
CGM.getContext().getASTRecordLayout(VBPtrSubobject.getBase());
const ASTRecordLayout &DerivedLayout =
CGM.getContext().getASTRecordLayout(RD);
SmallVector<llvm::Constant *, 4> Offsets;
// The offset from ReusingBase's vbptr to itself always leads.
CharUnits VBPtrOffset = BaseLayout.getVBPtrOffset();
Offsets.push_back(
llvm::ConstantInt::get(CGM.IntTy, -VBPtrOffset.getQuantity()));
// These are laid out in the same order as in Itanium, which is the same as
// the order of the vbase iterator.
for (CXXRecordDecl::base_class_const_iterator I = ReusingBase->vbases_begin(),
E = ReusingBase->vbases_end(); I != E; ++I) {
const CXXRecordDecl *VBase = I->getType()->getAsCXXRecordDecl();
CharUnits Offset = DerivedLayout.getVBaseClassOffset(VBase);
assert(!Offset.isNegative());
// Make it relative to the subobject vbptr.
Offset -= VBPtrSubobject.getBaseOffset() + VBPtrOffset;
Offsets.push_back(llvm::ConstantInt::get(CGM.IntTy, Offset.getQuantity()));
}
assert(Offsets.size() ==
cast<llvm::ArrayType>(cast<llvm::PointerType>(GV->getType())
->getElementType())->getNumElements());
llvm::ArrayType *VBTableType =
llvm::ArrayType::get(CGM.IntTy, Offsets.size());
llvm::Constant *Init = llvm::ConstantArray::get(VBTableType, Offsets);
GV->setInitializer(Init);
// Set the correct linkage.
GV->setLinkage(Linkage);
// Set the right visibility.
CGM.setTypeVisibility(GV, RD, CodeGenModule::TVK_ForVTable);
}
/// Check if we are casting to a struct with a flexible array at the end.
/// \code
/// struct foo {
/// size_t len;
/// struct bar data[];
/// };
/// \endcode
/// or
/// \code
/// struct foo {
/// size_t len;
/// struct bar data[0];
/// }
/// \endcode
/// In these cases it is also valid to allocate size of struct foo + a multiple
/// of struct bar.
static bool evenFlexibleArraySize(ASTContext &Ctx, CharUnits RegionSize,
CharUnits TypeSize, QualType ToPointeeTy) {
const RecordType *RT = ToPointeeTy->getAs<RecordType>();
if (!RT)
return false;
const RecordDecl *RD = RT->getDecl();
RecordDecl::field_iterator Iter(RD->field_begin());
RecordDecl::field_iterator End(RD->field_end());
const FieldDecl *Last = 0;
for (; Iter != End; ++Iter)
Last = *Iter;
assert(Last && "empty structs should already be handled");
const Type *ElemType = Last->getType()->getArrayElementTypeNoTypeQual();
CharUnits FlexSize;
if (const ConstantArrayType *ArrayTy =
Ctx.getAsConstantArrayType(Last->getType())) {
FlexSize = Ctx.getTypeSizeInChars(ElemType);
if (ArrayTy->getSize() == 1 && TypeSize > FlexSize)
TypeSize -= FlexSize;
else if (ArrayTy->getSize() != 0)
return false;
} else if (RD->hasFlexibleArrayMember()) {
FlexSize = Ctx.getTypeSizeInChars(ElemType);
} else {
return false;
}
if (FlexSize.isZero())
return false;
CharUnits Left = RegionSize - TypeSize;
if (Left.isNegative())
return false;
if (Left % FlexSize == 0)
return true;
return false;
}
