| //=== ASTRecordLayoutBuilder.cpp - Helper class for building record layouts ==// |
| // |
| // The LLVM Compiler Infrastructure |
| // |
| // This file is distributed under the University of Illinois Open Source |
| // License. See LICENSE.TXT for details. |
| // |
| //===----------------------------------------------------------------------===// |
| |
| #include "RecordLayoutBuilder.h" |
| |
| #include "clang/AST/Attr.h" |
| #include "clang/AST/Decl.h" |
| #include "clang/AST/DeclCXX.h" |
| #include "clang/AST/DeclObjC.h" |
| #include "clang/AST/Expr.h" |
| #include "clang/Basic/TargetInfo.h" |
| #include <llvm/ADT/SmallSet.h> |
| #include <llvm/Support/MathExtras.h> |
| |
| using namespace clang; |
| |
| ASTRecordLayoutBuilder::ASTRecordLayoutBuilder(ASTContext &Ctx) |
| : Ctx(Ctx), Size(0), Alignment(8), Packed(false), UnfilledBitsInLastByte(0), |
| MaxFieldAlignment(0), DataSize(0), IsUnion(false), NonVirtualSize(0), |
| NonVirtualAlignment(8), FirstNearlyEmptyVBase(0) { } |
| |
| /// IsNearlyEmpty - Indicates when a class has a vtable pointer, but |
| /// no other data. |
| bool ASTRecordLayoutBuilder::IsNearlyEmpty(const CXXRecordDecl *RD) const { |
| // FIXME: Audit the corners |
| if (!RD->isDynamicClass()) |
| return false; |
| const ASTRecordLayout &BaseInfo = Ctx.getASTRecordLayout(RD); |
| if (BaseInfo.getNonVirtualSize() == Ctx.Target.getPointerWidth(0)) |
| return true; |
| return false; |
| } |
| |
| void ASTRecordLayoutBuilder::IdentifyPrimaryBases(const CXXRecordDecl *RD) { |
| const ASTRecordLayout::PrimaryBaseInfo &BaseInfo = |
| Ctx.getASTRecordLayout(RD).getPrimaryBaseInfo(); |
| |
| // If the record has a primary base class that is virtual, add it to the set |
| // of primary bases. |
| if (BaseInfo.isVirtual()) |
| IndirectPrimaryBases.insert(BaseInfo.getBase()); |
| |
| // Now traverse all bases and find primary bases for them. |
| for (CXXRecordDecl::base_class_const_iterator i = RD->bases_begin(), |
| e = RD->bases_end(); i != e; ++i) { |
| assert(!i->getType()->isDependentType() && |
| "Cannot layout class with dependent bases."); |
| const CXXRecordDecl *Base = |
| cast<CXXRecordDecl>(i->getType()->getAs<RecordType>()->getDecl()); |
| |
| // Only bases with virtual bases participate in computing the |
| // indirect primary virtual base classes. |
| if (Base->getNumVBases()) |
| IdentifyPrimaryBases(Base); |
| } |
| } |
| |
| void |
| ASTRecordLayoutBuilder::SelectPrimaryVBase(const CXXRecordDecl *RD) { |
| for (CXXRecordDecl::base_class_const_iterator I = RD->bases_begin(), |
| E = RD->bases_end(); I != E; ++I) { |
| assert(!I->getType()->isDependentType() && |
| "Cannot layout class with dependent bases."); |
| |
| const CXXRecordDecl *Base = |
| cast<CXXRecordDecl>(I->getType()->getAs<RecordType>()->getDecl()); |
| |
| // Check if this is a nearly empty virtual base. |
| if (I->isVirtual() && IsNearlyEmpty(Base)) { |
| // If it's not an indirect primary base, then we've found our primary |
| // base. |
| if (!IndirectPrimaryBases.count(Base)) { |
| PrimaryBase = ASTRecordLayout::PrimaryBaseInfo(Base, |
| /*IsVirtual=*/true); |
| return; |
| } |
| |
| // Is this the first nearly empty virtual base? |
| if (!FirstNearlyEmptyVBase) |
| FirstNearlyEmptyVBase = Base; |
| } |
| |
| SelectPrimaryVBase(Base); |
| if (PrimaryBase.getBase()) |
| return; |
| } |
| } |
| |
| /// DeterminePrimaryBase - Determine the primary base of the given class. |
| void ASTRecordLayoutBuilder::DeterminePrimaryBase(const CXXRecordDecl *RD) { |
| // If the class isn't dynamic, it won't have a primary base. |
| if (!RD->isDynamicClass()) |
| return; |
| |
| // Compute all the primary virtual bases for all of our direct and |
| // indirect bases, and record all their primary virtual base classes. |
| for (CXXRecordDecl::base_class_const_iterator i = RD->bases_begin(), |
| e = RD->bases_end(); i != e; ++i) { |
| assert(!i->getType()->isDependentType() && |
| "Cannot lay out class with dependent bases."); |
| const CXXRecordDecl *Base = |
| cast<CXXRecordDecl>(i->getType()->getAs<RecordType>()->getDecl()); |
| IdentifyPrimaryBases(Base); |
| } |
| |
| // If the record has a dynamic base class, attempt to choose a primary base |
| // class. It is the first (in direct base class order) non-virtual dynamic |
| // base class, if one exists. |
| for (CXXRecordDecl::base_class_const_iterator i = RD->bases_begin(), |
| e = RD->bases_end(); i != e; ++i) { |
| // Ignore virtual bases. |
| if (i->isVirtual()) |
| continue; |
| |
| const CXXRecordDecl *Base = |
| cast<CXXRecordDecl>(i->getType()->getAs<RecordType>()->getDecl()); |
| |
| if (Base->isDynamicClass()) { |
| // We found it. |
| PrimaryBase = ASTRecordLayout::PrimaryBaseInfo(Base, /*IsVirtual=*/false); |
| return; |
| } |
| } |
| |
| // Otherwise, it is the first nearly empty virtual base that is not an |
| // indirect primary virtual base class, if one exists. |
| if (RD->getNumVBases() != 0) { |
| SelectPrimaryVBase(RD); |
| if (PrimaryBase.getBase()) |
| return; |
| } |
| |
| // Otherwise, it is the first nearly empty virtual base that is not an |
| // indirect primary virtual base class, if one exists. |
| if (FirstNearlyEmptyVBase) { |
| PrimaryBase = ASTRecordLayout::PrimaryBaseInfo(FirstNearlyEmptyVBase, |
| /*IsVirtual=*/true); |
| return; |
| } |
| |
| // Otherwise there is no primary base class. |
| assert(!PrimaryBase.getBase() && "Should not get here with a primary base!"); |
| |
| // Allocate the virtual table pointer at offset zero. |
| assert(DataSize == 0 && "Vtable pointer must be at offset zero!"); |
| |
| // Update the size. |
| Size += Ctx.Target.getPointerWidth(0); |
| DataSize = Size; |
| |
| // Update the alignment. |
| UpdateAlignment(Ctx.Target.getPointerAlign(0)); |
| } |
| |
| void |
| ASTRecordLayoutBuilder::LayoutNonVirtualBases(const CXXRecordDecl *RD) { |
| // First, determine the primary base class. |
| DeterminePrimaryBase(RD); |
| |
| // If we have a primary base class, lay it out. |
| if (const CXXRecordDecl *Base = PrimaryBase.getBase()) { |
| if (PrimaryBase.isVirtual()) { |
| // We have a virtual primary base, insert it as an indirect primary base. |
| IndirectPrimaryBases.insert(Base); |
| |
| LayoutVirtualBase(Base); |
| } else |
| LayoutNonVirtualBase(Base); |
| } |
| |
| // Now lay out the non-virtual bases. |
| for (CXXRecordDecl::base_class_const_iterator I = RD->bases_begin(), |
| E = RD->bases_end(); I != E; ++I) { |
| |
| // Ignore virtual bases. |
| if (I->isVirtual()) |
| continue; |
| |
| const CXXRecordDecl *Base = |
| cast<CXXRecordDecl>(I->getType()->getAs<RecordType>()->getDecl()); |
| |
| // Skip the primary base. |
| if (Base == PrimaryBase.getBase() && !PrimaryBase.isVirtual()) |
| continue; |
| |
| // Lay out the base. |
| LayoutNonVirtualBase(Base); |
| } |
| } |
| |
| void ASTRecordLayoutBuilder::LayoutNonVirtualBase(const CXXRecordDecl *RD) { |
| // Layout the base. |
| uint64_t Offset = LayoutBase(RD); |
| |
| // Add its base class offset. |
| if (!Bases.insert(std::make_pair(RD, Offset)).second) |
| assert(false && "Added same base offset more than once!"); |
| } |
| |
| void |
| ASTRecordLayoutBuilder::LayoutVirtualBases(const CXXRecordDecl *RD, |
| uint64_t Offset, |
| const CXXRecordDecl *MostDerivedClass) { |
| const CXXRecordDecl *PrimaryBase; |
| |
| if (MostDerivedClass == RD) |
| PrimaryBase = this->PrimaryBase.getBase(); |
| else { |
| const ASTRecordLayout &Layout = Ctx.getASTRecordLayout(RD); |
| PrimaryBase = Layout.getPrimaryBase(); |
| } |
| |
| for (CXXRecordDecl::base_class_const_iterator I = RD->bases_begin(), |
| E = RD->bases_end(); I != E; ++I) { |
| assert(!I->getType()->isDependentType() && |
| "Cannot layout class with dependent bases."); |
| |
| const CXXRecordDecl *Base = |
| cast<CXXRecordDecl>(I->getType()->getAs<RecordType>()->getDecl()); |
| |
| if (I->isVirtual()) { |
| bool IndirectPrimaryBase = IndirectPrimaryBases.count(Base); |
| |
| // We only want to visit this virtual base if it's either a primary base, |
| // or not an indirect primary base. |
| if (Base == PrimaryBase || !IndirectPrimaryBase) { |
| // Only lay things out once. |
| if (!VisitedVirtualBases.insert(Base)) |
| continue; |
| |
| if (Base == PrimaryBase) { |
| assert(IndirectPrimaryBase && |
| "Base is supposed to be an indirect primary base!"); |
| |
| // We only want to add a vbase offset if this primary base is not the |
| // primary base of the most derived class. |
| if (PrimaryBase != this->PrimaryBase.getBase() || |
| !this->PrimaryBase.isVirtual()) { |
| if (!VBases.insert(std::make_pair(Base, Offset)).second) |
| assert(false && "Added same vbase offset more than once!"); |
| } |
| } else { |
| // We actually do want to lay out this base. |
| LayoutVirtualBase(Base); |
| } |
| } |
| } |
| |
| if (!Base->getNumVBases()) { |
| // This base isn't interesting since it doesn't have any virtual bases. |
| continue; |
| } |
| |
| // Compute the offset of this base. |
| uint64_t BaseOffset; |
| |
| if (I->isVirtual()) { |
| // We want the vbase offset from the class we're currently laying out. |
| assert(VBases.count(Base) && "Did not find virtual base!"); |
| BaseOffset = VBases[Base]; |
| } else if (RD == MostDerivedClass) { |
| // We want the base offset from the class we're currently laying out. |
| assert(Bases.count(Base) && "Did not find base!"); |
| BaseOffset = Bases[Base]; |
| } else { |
| const ASTRecordLayout &Layout = Ctx.getASTRecordLayout(RD); |
| BaseOffset = Offset + Layout.getBaseClassOffset(Base); |
| } |
| |
| LayoutVirtualBases(Base, BaseOffset, MostDerivedClass); |
| } |
| } |
| |
| void ASTRecordLayoutBuilder::LayoutVirtualBase(const CXXRecordDecl *RD) { |
| // Layout the base. |
| uint64_t Offset = LayoutBase(RD); |
| |
| // Add its base class offset. |
| if (!VBases.insert(std::make_pair(RD, Offset)).second) |
| assert(false && "Added same vbase offset more than once!"); |
| } |
| |
| uint64_t ASTRecordLayoutBuilder::LayoutBase(const CXXRecordDecl *RD) { |
| const ASTRecordLayout &BaseInfo = Ctx.getASTRecordLayout(RD); |
| |
| // If we have an empty base class, try to place it at offset 0. |
| if (RD->isEmpty() && canPlaceRecordAtOffset(RD, 0)) { |
| // We were able to place the class at offset 0. |
| UpdateEmptyClassOffsets(RD, 0); |
| |
| Size = std::max(Size, BaseInfo.getSize()); |
| |
| return 0; |
| } |
| |
| unsigned BaseAlign = BaseInfo.getNonVirtualAlign(); |
| |
| // Round up the current record size to the base's alignment boundary. |
| uint64_t Offset = llvm::RoundUpToAlignment(DataSize, BaseAlign); |
| |
| // Try to place the base. |
| while (true) { |
| if (canPlaceRecordAtOffset(RD, Offset)) |
| break; |
| |
| Offset += BaseAlign; |
| } |
| |
| if (!RD->isEmpty()) { |
| // Update the data size. |
| DataSize = Offset + BaseInfo.getNonVirtualSize(); |
| |
| Size = std::max(Size, DataSize); |
| } else |
| Size = std::max(Size, Offset + BaseInfo.getSize()); |
| |
| // Remember max struct/class alignment. |
| UpdateAlignment(BaseAlign); |
| |
| UpdateEmptyClassOffsets(RD, Offset); |
| return Offset; |
| } |
| |
| bool ASTRecordLayoutBuilder::canPlaceRecordAtOffset(const CXXRecordDecl *RD, |
| uint64_t Offset) const { |
| // Look for an empty class with the same type at the same offset. |
| for (EmptyClassOffsetsTy::const_iterator I = |
| EmptyClassOffsets.lower_bound(Offset), |
| E = EmptyClassOffsets.upper_bound(Offset); I != E; ++I) { |
| |
| if (I->second == RD) |
| return false; |
| } |
| |
| const ASTRecordLayout &Info = Ctx.getASTRecordLayout(RD); |
| |
| // Check bases. |
| for (CXXRecordDecl::base_class_const_iterator I = RD->bases_begin(), |
| E = RD->bases_end(); I != E; ++I) { |
| assert(!I->getType()->isDependentType() && |
| "Cannot layout class with dependent bases."); |
| if (I->isVirtual()) |
| continue; |
| |
| const CXXRecordDecl *Base = |
| cast<CXXRecordDecl>(I->getType()->getAs<RecordType>()->getDecl()); |
| |
| uint64_t BaseClassOffset = Info.getBaseClassOffset(Base); |
| |
| if (!canPlaceRecordAtOffset(Base, Offset + BaseClassOffset)) |
| return false; |
| } |
| |
| // Check fields. |
| unsigned FieldNo = 0; |
| for (CXXRecordDecl::field_iterator I = RD->field_begin(), E = RD->field_end(); |
| I != E; ++I, ++FieldNo) { |
| const FieldDecl *FD = *I; |
| |
| uint64_t FieldOffset = Info.getFieldOffset(FieldNo); |
| |
| if (!canPlaceFieldAtOffset(FD, Offset + FieldOffset)) |
| return false; |
| } |
| |
| // FIXME: virtual bases. |
| return true; |
| } |
| |
| bool ASTRecordLayoutBuilder::canPlaceFieldAtOffset(const FieldDecl *FD, |
| uint64_t Offset) const { |
| QualType T = FD->getType(); |
| if (const RecordType *RT = T->getAs<RecordType>()) { |
| if (const CXXRecordDecl *RD = dyn_cast<CXXRecordDecl>(RT->getDecl())) |
| return canPlaceRecordAtOffset(RD, Offset); |
| } |
| |
| if (const ConstantArrayType *AT = Ctx.getAsConstantArrayType(T)) { |
| QualType ElemTy = Ctx.getBaseElementType(AT); |
| const RecordType *RT = ElemTy->getAs<RecordType>(); |
| if (!RT) |
| return true; |
| const CXXRecordDecl *RD = dyn_cast<CXXRecordDecl>(RT->getDecl()); |
| if (!RD) |
| return true; |
| |
| const ASTRecordLayout &Info = Ctx.getASTRecordLayout(RD); |
| |
| uint64_t NumElements = Ctx.getConstantArrayElementCount(AT); |
| uint64_t ElementOffset = Offset; |
| for (uint64_t I = 0; I != NumElements; ++I) { |
| if (!canPlaceRecordAtOffset(RD, ElementOffset)) |
| return false; |
| |
| ElementOffset += Info.getSize(); |
| } |
| } |
| |
| return true; |
| } |
| |
| void ASTRecordLayoutBuilder::UpdateEmptyClassOffsets(const CXXRecordDecl *RD, |
| uint64_t Offset) { |
| if (RD->isEmpty()) |
| EmptyClassOffsets.insert(std::make_pair(Offset, RD)); |
| |
| const ASTRecordLayout &Info = Ctx.getASTRecordLayout(RD); |
| |
| // Update bases. |
| for (CXXRecordDecl::base_class_const_iterator I = RD->bases_begin(), |
| E = RD->bases_end(); I != E; ++I) { |
| assert(!I->getType()->isDependentType() && |
| "Cannot layout class with dependent bases."); |
| if (I->isVirtual()) |
| continue; |
| |
| const CXXRecordDecl *Base = |
| cast<CXXRecordDecl>(I->getType()->getAs<RecordType>()->getDecl()); |
| |
| uint64_t BaseClassOffset = Info.getBaseClassOffset(Base); |
| UpdateEmptyClassOffsets(Base, Offset + BaseClassOffset); |
| } |
| |
| // Update fields. |
| unsigned FieldNo = 0; |
| for (CXXRecordDecl::field_iterator I = RD->field_begin(), E = RD->field_end(); |
| I != E; ++I, ++FieldNo) { |
| const FieldDecl *FD = *I; |
| |
| uint64_t FieldOffset = Info.getFieldOffset(FieldNo); |
| UpdateEmptyClassOffsets(FD, Offset + FieldOffset); |
| } |
| |
| // FIXME: Update virtual bases. |
| } |
| |
| void |
| ASTRecordLayoutBuilder::UpdateEmptyClassOffsets(const FieldDecl *FD, |
| uint64_t Offset) { |
| QualType T = FD->getType(); |
| |
| if (const RecordType *RT = T->getAs<RecordType>()) { |
| if (const CXXRecordDecl *RD = dyn_cast<CXXRecordDecl>(RT->getDecl())) { |
| UpdateEmptyClassOffsets(RD, Offset); |
| return; |
| } |
| } |
| |
| if (const ConstantArrayType *AT = Ctx.getAsConstantArrayType(T)) { |
| QualType ElemTy = Ctx.getBaseElementType(AT); |
| const RecordType *RT = ElemTy->getAs<RecordType>(); |
| if (!RT) |
| return; |
| const CXXRecordDecl *RD = dyn_cast<CXXRecordDecl>(RT->getDecl()); |
| if (!RD) |
| return; |
| |
| const ASTRecordLayout &Info = Ctx.getASTRecordLayout(RD); |
| |
| uint64_t NumElements = Ctx.getConstantArrayElementCount(AT); |
| uint64_t ElementOffset = Offset; |
| |
| for (uint64_t I = 0; I != NumElements; ++I) { |
| UpdateEmptyClassOffsets(RD, ElementOffset); |
| ElementOffset += Info.getSize(); |
| } |
| } |
| } |
| |
| void ASTRecordLayoutBuilder::Layout(const RecordDecl *D) { |
| IsUnion = D->isUnion(); |
| |
| Packed = D->hasAttr<PackedAttr>(); |
| |
| // The #pragma pack attribute specifies the maximum field alignment. |
| if (const PragmaPackAttr *PPA = D->getAttr<PragmaPackAttr>()) |
| MaxFieldAlignment = PPA->getAlignment(); |
| |
| if (const AlignedAttr *AA = D->getAttr<AlignedAttr>()) |
| UpdateAlignment(AA->getMaxAlignment()); |
| |
| // If this is a C++ class, lay out the vtable and the non-virtual bases. |
| const CXXRecordDecl *RD = dyn_cast<CXXRecordDecl>(D); |
| if (RD) |
| LayoutNonVirtualBases(RD); |
| |
| LayoutFields(D); |
| |
| NonVirtualSize = Size; |
| NonVirtualAlignment = Alignment; |
| |
| // If this is a C++ class, lay out its virtual bases. |
| if (RD) |
| LayoutVirtualBases(RD, 0, RD); |
| |
| // Finally, round the size of the total struct up to the alignment of the |
| // struct itself. |
| FinishLayout(); |
| } |
| |
| // FIXME. Impl is no longer needed. |
| void ASTRecordLayoutBuilder::Layout(const ObjCInterfaceDecl *D, |
| const ObjCImplementationDecl *Impl) { |
| if (ObjCInterfaceDecl *SD = D->getSuperClass()) { |
| const ASTRecordLayout &SL = Ctx.getASTObjCInterfaceLayout(SD); |
| |
| UpdateAlignment(SL.getAlignment()); |
| |
| // We start laying out ivars not at the end of the superclass |
| // structure, but at the next byte following the last field. |
| Size = llvm::RoundUpToAlignment(SL.getDataSize(), 8); |
| DataSize = Size; |
| } |
| |
| Packed = D->hasAttr<PackedAttr>(); |
| |
| // The #pragma pack attribute specifies the maximum field alignment. |
| if (const PragmaPackAttr *PPA = D->getAttr<PragmaPackAttr>()) |
| MaxFieldAlignment = PPA->getAlignment(); |
| |
| if (const AlignedAttr *AA = D->getAttr<AlignedAttr>()) |
| UpdateAlignment(AA->getMaxAlignment()); |
| // Layout each ivar sequentially. |
| llvm::SmallVector<ObjCIvarDecl*, 16> Ivars; |
| Ctx.ShallowCollectObjCIvars(D, Ivars); |
| for (unsigned i = 0, e = Ivars.size(); i != e; ++i) |
| LayoutField(Ivars[i]); |
| |
| // Finally, round the size of the total struct up to the alignment of the |
| // struct itself. |
| FinishLayout(); |
| } |
| |
| void ASTRecordLayoutBuilder::LayoutFields(const RecordDecl *D) { |
| // Layout each field, for now, just sequentially, respecting alignment. In |
| // the future, this will need to be tweakable by targets. |
| for (RecordDecl::field_iterator Field = D->field_begin(), |
| FieldEnd = D->field_end(); Field != FieldEnd; ++Field) |
| LayoutField(*Field); |
| } |
| |
| void ASTRecordLayoutBuilder::LayoutBitField(const FieldDecl *D) { |
| bool FieldPacked = Packed || D->hasAttr<PackedAttr>(); |
| uint64_t FieldOffset = IsUnion ? 0 : (DataSize - UnfilledBitsInLastByte); |
| uint64_t FieldSize = D->getBitWidth()->EvaluateAsInt(Ctx).getZExtValue(); |
| |
| std::pair<uint64_t, unsigned> FieldInfo = Ctx.getTypeInfo(D->getType()); |
| uint64_t TypeSize = FieldInfo.first; |
| unsigned FieldAlign = FieldInfo.second; |
| |
| if (FieldPacked) |
| FieldAlign = 1; |
| if (const AlignedAttr *AA = D->getAttr<AlignedAttr>()) |
| FieldAlign = std::max(FieldAlign, AA->getMaxAlignment()); |
| |
| // The maximum field alignment overrides the aligned attribute. |
| if (MaxFieldAlignment) |
| FieldAlign = std::min(FieldAlign, MaxFieldAlignment); |
| |
| // Check if we need to add padding to give the field the correct |
| // alignment. |
| if (FieldSize == 0 || (FieldOffset & (FieldAlign-1)) + FieldSize > TypeSize) |
| FieldOffset = (FieldOffset + (FieldAlign-1)) & ~(FieldAlign-1); |
| |
| // Padding members don't affect overall alignment |
| if (!D->getIdentifier()) |
| FieldAlign = 1; |
| |
| // Place this field at the current location. |
| FieldOffsets.push_back(FieldOffset); |
| |
| // Update DataSize to include the last byte containing (part of) the bitfield. |
| if (IsUnion) { |
| // FIXME: I think FieldSize should be TypeSize here. |
| DataSize = std::max(DataSize, FieldSize); |
| } else { |
| uint64_t NewSizeInBits = FieldOffset + FieldSize; |
| |
| DataSize = llvm::RoundUpToAlignment(NewSizeInBits, 8); |
| UnfilledBitsInLastByte = DataSize - NewSizeInBits; |
| } |
| |
| // Update the size. |
| Size = std::max(Size, DataSize); |
| |
| // Remember max struct/class alignment. |
| UpdateAlignment(FieldAlign); |
| } |
| |
| void ASTRecordLayoutBuilder::LayoutField(const FieldDecl *D) { |
| if (D->isBitField()) { |
| LayoutBitField(D); |
| return; |
| } |
| |
| // Reset the unfilled bits. |
| UnfilledBitsInLastByte = 0; |
| |
| bool FieldPacked = Packed || D->hasAttr<PackedAttr>(); |
| uint64_t FieldOffset = IsUnion ? 0 : DataSize; |
| uint64_t FieldSize; |
| unsigned FieldAlign; |
| |
| if (D->getType()->isIncompleteArrayType()) { |
| // This is a flexible array member; we can't directly |
| // query getTypeInfo about these, so we figure it out here. |
| // Flexible array members don't have any size, but they |
| // have to be aligned appropriately for their element type. |
| FieldSize = 0; |
| const ArrayType* ATy = Ctx.getAsArrayType(D->getType()); |
| FieldAlign = Ctx.getTypeAlign(ATy->getElementType()); |
| } else if (const ReferenceType *RT = D->getType()->getAs<ReferenceType>()) { |
| unsigned AS = RT->getPointeeType().getAddressSpace(); |
| FieldSize = Ctx.Target.getPointerWidth(AS); |
| FieldAlign = Ctx.Target.getPointerAlign(AS); |
| } else { |
| std::pair<uint64_t, unsigned> FieldInfo = Ctx.getTypeInfo(D->getType()); |
| FieldSize = FieldInfo.first; |
| FieldAlign = FieldInfo.second; |
| } |
| |
| if (FieldPacked) |
| FieldAlign = 8; |
| if (const AlignedAttr *AA = D->getAttr<AlignedAttr>()) |
| FieldAlign = std::max(FieldAlign, AA->getMaxAlignment()); |
| |
| // The maximum field alignment overrides the aligned attribute. |
| if (MaxFieldAlignment) |
| FieldAlign = std::min(FieldAlign, MaxFieldAlignment); |
| |
| // Round up the current record size to the field's alignment boundary. |
| FieldOffset = llvm::RoundUpToAlignment(FieldOffset, FieldAlign); |
| |
| if (!IsUnion) { |
| while (true) { |
| // Check if we can place the field at this offset. |
| if (canPlaceFieldAtOffset(D, FieldOffset)) |
| break; |
| |
| // We couldn't place the field at the offset. Try again at a new offset. |
| FieldOffset += FieldAlign; |
| } |
| |
| UpdateEmptyClassOffsets(D, FieldOffset); |
| } |
| |
| // Place this field at the current location. |
| FieldOffsets.push_back(FieldOffset); |
| |
| // Reserve space for this field. |
| if (IsUnion) |
| Size = std::max(Size, FieldSize); |
| else |
| Size = FieldOffset + FieldSize; |
| |
| // Update the data size. |
| DataSize = Size; |
| |
| // Remember max struct/class alignment. |
| UpdateAlignment(FieldAlign); |
| } |
| |
| void ASTRecordLayoutBuilder::FinishLayout() { |
| // In C++, records cannot be of size 0. |
| if (Ctx.getLangOptions().CPlusPlus && Size == 0) |
| Size = 8; |
| // Finally, round the size of the record up to the alignment of the |
| // record itself. |
| Size = llvm::RoundUpToAlignment(Size, Alignment); |
| } |
| |
| void ASTRecordLayoutBuilder::UpdateAlignment(unsigned NewAlignment) { |
| if (NewAlignment <= Alignment) |
| return; |
| |
| assert(llvm::isPowerOf2_32(NewAlignment && "Alignment not a power of 2")); |
| |
| Alignment = NewAlignment; |
| } |
| |
| const ASTRecordLayout * |
| ASTRecordLayoutBuilder::ComputeLayout(ASTContext &Ctx, |
| const RecordDecl *D) { |
| ASTRecordLayoutBuilder Builder(Ctx); |
| |
| Builder.Layout(D); |
| |
| if (!isa<CXXRecordDecl>(D)) |
| return new (Ctx) ASTRecordLayout(Ctx, Builder.Size, Builder.Alignment, |
| Builder.Size, |
| Builder.FieldOffsets.data(), |
| Builder.FieldOffsets.size()); |
| |
| // FIXME: This is not always correct. See the part about bitfields at |
| // http://www.codesourcery.com/public/cxx-abi/abi.html#POD for more info. |
| // FIXME: IsPODForThePurposeOfLayout should be stored in the record layout. |
| bool IsPODForThePurposeOfLayout = cast<CXXRecordDecl>(D)->isPOD(); |
| |
| // FIXME: This should be done in FinalizeLayout. |
| uint64_t DataSize = |
| IsPODForThePurposeOfLayout ? Builder.Size : Builder.DataSize; |
| uint64_t NonVirtualSize = |
| IsPODForThePurposeOfLayout ? DataSize : Builder.NonVirtualSize; |
| |
| return new (Ctx) ASTRecordLayout(Ctx, Builder.Size, Builder.Alignment, |
| DataSize, Builder.FieldOffsets.data(), |
| Builder.FieldOffsets.size(), |
| NonVirtualSize, |
| Builder.NonVirtualAlignment, |
| Builder.PrimaryBase, |
| Builder.Bases, Builder.VBases); |
| } |
| |
| const ASTRecordLayout * |
| ASTRecordLayoutBuilder::ComputeLayout(ASTContext &Ctx, |
| const ObjCInterfaceDecl *D, |
| const ObjCImplementationDecl *Impl) { |
| ASTRecordLayoutBuilder Builder(Ctx); |
| |
| Builder.Layout(D, Impl); |
| |
| return new (Ctx) ASTRecordLayout(Ctx, Builder.Size, Builder.Alignment, |
| Builder.DataSize, |
| Builder.FieldOffsets.data(), |
| Builder.FieldOffsets.size()); |
| } |
| |
| const CXXMethodDecl * |
| ASTRecordLayoutBuilder::ComputeKeyFunction(const CXXRecordDecl *RD) { |
| assert(RD->isDynamicClass() && "Class does not have any virtual methods!"); |
| |
| // If a class isnt' polymorphic it doesn't have a key function. |
| if (!RD->isPolymorphic()) |
| return 0; |
| |
| // A class inside an anonymous namespace doesn't have a key function. (Or |
| // at least, there's no point to assigning a key function to such a class; |
| // this doesn't affect the ABI.) |
| if (RD->isInAnonymousNamespace()) |
| return 0; |
| |
| for (CXXRecordDecl::method_iterator I = RD->method_begin(), |
| E = RD->method_end(); I != E; ++I) { |
| const CXXMethodDecl *MD = *I; |
| |
| if (!MD->isVirtual()) |
| continue; |
| |
| if (MD->isPure()) |
| continue; |
| |
| // Ignore implicit member functions, they are always marked as inline, but |
| // they don't have a body until they're defined. |
| if (MD->isImplicit()) |
| continue; |
| |
| if (MD->isInlineSpecified()) |
| continue; |
| |
| if (MD->hasInlineBody()) |
| continue; |
| |
| // We found it. |
| return MD; |
| } |
| |
| return 0; |
| } |
| |