diff options
Diffstat (limited to 'clang/lib/AST/RecordLayoutBuilder.cpp')
| -rw-r--r-- | clang/lib/AST/RecordLayoutBuilder.cpp | 458 |
1 files changed, 70 insertions, 388 deletions
diff --git a/clang/lib/AST/RecordLayoutBuilder.cpp b/clang/lib/AST/RecordLayoutBuilder.cpp index a79cbdd84bb..edef526fa66 100644 --- a/clang/lib/AST/RecordLayoutBuilder.cpp +++ b/clang/lib/AST/RecordLayoutBuilder.cpp @@ -604,13 +604,6 @@ protected: /// pointer, as opposed to inheriting one from a primary base class. bool HasOwnVFPtr; - /// HasOwnVBPtr - Whether the class provides its own vbtbl - /// pointer, as opposed to inheriting one from a base class. Only for MS. - bool HasOwnVBPtr; - - /// VBPtrOffset - Virtual base table offset. Only for MS layout. - CharUnits VBPtrOffset; - typedef llvm::DenseMap<const CXXRecordDecl *, CharUnits> BaseOffsetsMapTy; /// Bases - base classes and their offsets in the record. @@ -658,8 +651,6 @@ protected: NonVirtualAlignment(CharUnits::One()), PrimaryBase(0), PrimaryBaseIsVirtual(false), HasOwnVFPtr(false), - HasOwnVBPtr(false), - VBPtrOffset(CharUnits::fromQuantity(-1)), FirstNearlyEmptyVBase(0) { } /// Reset this RecordLayoutBuilder to a fresh state, using the given @@ -687,12 +678,6 @@ protected: return Context.getTargetInfo().getCXXABI(); } - bool isMicrosoftCXXABI() const { - return getCXXABI().isMicrosoft(); - } - - void MSLayoutVirtualBases(const CXXRecordDecl *RD); - /// BaseSubobjectInfoAllocator - Allocator for BaseSubobjectInfo objects. llvm::SpecificBumpPtrAllocator<BaseSubobjectInfo> BaseSubobjectInfoAllocator; @@ -734,21 +719,12 @@ protected: void AddPrimaryVirtualBaseOffsets(const BaseSubobjectInfo *Info, CharUnits Offset); - bool needsVFTable(const CXXRecordDecl *RD) const; - bool hasNewVirtualFunction(const CXXRecordDecl *RD, - bool IgnoreDestructor = false) const; - bool isPossiblePrimaryBase(const CXXRecordDecl *Base) const; - - void computeVtordisps(const CXXRecordDecl *RD, - ClassSetTy &VtordispVBases); - /// LayoutVirtualBases - Lays out all the virtual bases. void LayoutVirtualBases(const CXXRecordDecl *RD, const CXXRecordDecl *MostDerivedClass); /// LayoutVirtualBase - Lays out a single virtual base. - void LayoutVirtualBase(const BaseSubobjectInfo *Base, - bool IsVtordispNeed = false); + void LayoutVirtualBase(const BaseSubobjectInfo *Base); /// LayoutBase - Will lay out a base and return the offset where it was /// placed, in chars. @@ -858,7 +834,7 @@ void RecordLayoutBuilder::DeterminePrimaryBase(const CXXRecordDecl *RD) { const CXXRecordDecl *Base = cast<CXXRecordDecl>(i->getType()->getAs<RecordType>()->getDecl()); - if (isPossiblePrimaryBase(Base)) { + if (Base->isDynamicClass()) { // We found it. PrimaryBase = Base; PrimaryBaseIsVirtual = false; @@ -866,12 +842,6 @@ void RecordLayoutBuilder::DeterminePrimaryBase(const CXXRecordDecl *RD) { } } - // The Microsoft ABI doesn't have primary virtual bases. - if (isMicrosoftCXXABI()) { - assert(!PrimaryBase && "Should not get here with a primary base!"); - return; - } - // Under the Itanium ABI, if there is no non-virtual primary base class, // try to compute the primary virtual base. The primary virtual base is // the first nearly empty virtual base that is not an indirect primary @@ -1050,7 +1020,7 @@ RecordLayoutBuilder::LayoutNonVirtualBases(const CXXRecordDecl *RD) { // If this class needs a vtable/vf-table and didn't get one from a // primary base, add it in now. - } else if (needsVFTable(RD)) { + } else if (RD->isDynamicClass()) { assert(DataSize == 0 && "Vtable pointer must be at offset zero!"); CharUnits PtrWidth = Context.toCharUnitsFromBits(Context.getTargetInfo().getPointerWidth(0)); @@ -1094,38 +1064,6 @@ RecordLayoutBuilder::LayoutNonVirtualBases(const CXXRecordDecl *RD) { LayoutNonVirtualBase(BaseInfo); } - - // In the MS ABI, add the vb-table pointer if we need one, which is - // whenever we have a virtual base and we can't re-use a vb-table - // pointer from a non-virtual base. - if (isMicrosoftCXXABI() && - HasDirectVirtualBases && !HasNonVirtualBaseWithVBTable) { - CharUnits PtrWidth = - Context.toCharUnitsFromBits(Context.getTargetInfo().getPointerWidth(0)); - CharUnits PtrAlign = - Context.toCharUnitsFromBits(Context.getTargetInfo().getPointerAlign(0)); - - // MSVC potentially over-aligns the vb-table pointer by giving it - // the max alignment of all the non-virtual objects in the class. - // This is completely unnecessary, but we're not here to pass - // judgment. - // - // Note that we've only laid out the non-virtual bases, so on the - // first pass Alignment won't be set correctly here, but if the - // vb-table doesn't end up aligned correctly we'll come through - // and redo the layout from scratch with the right alignment. - // - // TODO: Instead of doing this, just lay out the fields as if the - // vb-table were at offset zero, then retroactively bump the field - // offsets up. - PtrAlign = std::max(PtrAlign, Alignment); - - EnsureVTablePointerAlignment(PtrAlign); - HasOwnVBPtr = true; - VBPtrOffset = getSize(); - setSize(getSize() + PtrWidth); - setDataSize(getSize()); - } } void RecordLayoutBuilder::LayoutNonVirtualBase(const BaseSubobjectInfo *Base) { @@ -1174,38 +1112,6 @@ RecordLayoutBuilder::AddPrimaryVirtualBaseOffsets(const BaseSubobjectInfo *Info, } } -/// needsVFTable - Return true if this class needs a vtable or vf-table -/// when laid out as a base class. These are treated the same because -/// they're both always laid out at offset zero. -/// -/// This function assumes that the class has no primary base. -bool RecordLayoutBuilder::needsVFTable(const CXXRecordDecl *RD) const { - assert(!PrimaryBase); - - // In the Itanium ABI, every dynamic class needs a vtable: even if - // this class has no virtual functions as a base class (i.e. it's - // non-polymorphic or only has virtual functions from virtual - // bases),x it still needs a vtable to locate its virtual bases. - if (!isMicrosoftCXXABI()) - return RD->isDynamicClass(); - - // In the MS ABI, we need a vfptr if the class has virtual functions - // other than those declared by its virtual bases. The AST doesn't - // tell us that directly, and checking manually for virtual - // functions that aren't overrides is expensive, but there are - // some important shortcuts: - - // - Non-polymorphic classes have no virtual functions at all. - if (!RD->isPolymorphic()) return false; - - // - Polymorphic classes with no virtual bases must either declare - // virtual functions directly or inherit them, but in the latter - // case we would have a primary base. - if (RD->getNumVBases() == 0) return true; - - return hasNewVirtualFunction(RD); -} - /// Does the given class inherit non-virtually from any of the classes /// in the given set? static bool hasNonVirtualBaseInSet(const CXXRecordDecl *RD, @@ -1228,195 +1134,6 @@ static bool hasNonVirtualBaseInSet(const CXXRecordDecl *RD, return false; } -/// Does the given method (B::foo()) already override a method (A::foo()) -/// such that A requires a vtordisp in B? If so, we don't need to add a -/// new vtordisp for B in a yet-more-derived class C providing C::foo(). -static bool overridesMethodRequiringVtorDisp(const ASTContext &Context, - const CXXMethodDecl *M) { - CXXMethodDecl::method_iterator - I = M->begin_overridden_methods(), E = M->end_overridden_methods(); - if (I == E) return false; - - const ASTRecordLayout::VBaseOffsetsMapTy &offsets = - Context.getASTRecordLayout(M->getParent()).getVBaseOffsetsMap(); - do { - const CXXMethodDecl *overridden = *I; - - // If the overridden method's class isn't recognized as a virtual - // base in the derived class, ignore it. - ASTRecordLayout::VBaseOffsetsMapTy::const_iterator - it = offsets.find(overridden->getParent()); - if (it == offsets.end()) continue; - - // Otherwise, check if the overridden method's class needs a vtordisp. - if (it->second.hasVtorDisp()) return true; - - } while (++I != E); - return false; -} - -/// In the Microsoft ABI, decide which of the virtual bases require a -/// vtordisp field. -void RecordLayoutBuilder::computeVtordisps(const CXXRecordDecl *RD, - ClassSetTy &vtordispVBases) { - // Bail out if we have no virtual bases. - assert(RD->getNumVBases()); - - // Build up the set of virtual bases that we haven't decided yet. - ClassSetTy undecidedVBases; - for (CXXRecordDecl::base_class_const_iterator - I = RD->vbases_begin(), E = RD->vbases_end(); I != E; ++I) { - const CXXRecordDecl *vbase = I->getType()->getAsCXXRecordDecl(); - undecidedVBases.insert(vbase); - } - assert(!undecidedVBases.empty()); - - // A virtual base requires a vtordisp field in a derived class if it - // requires a vtordisp field in a base class. Walk all the direct - // bases and collect this information. - for (CXXRecordDecl::base_class_const_iterator I = RD->bases_begin(), - E = RD->bases_end(); I != E; ++I) { - const CXXRecordDecl *base = I->getType()->getAsCXXRecordDecl(); - const ASTRecordLayout &baseLayout = Context.getASTRecordLayout(base); - - // Iterate over the set of virtual bases provided by this class. - for (ASTRecordLayout::VBaseOffsetsMapTy::const_iterator - VI = baseLayout.getVBaseOffsetsMap().begin(), - VE = baseLayout.getVBaseOffsetsMap().end(); VI != VE; ++VI) { - // If it doesn't need a vtordisp in this base, ignore it. - if (!VI->second.hasVtorDisp()) continue; - - // If we've already seen it and decided it needs a vtordisp, ignore it. - if (!undecidedVBases.erase(VI->first)) - continue; - - // Add it. - vtordispVBases.insert(VI->first); - - // Quit as soon as we've decided everything. - if (undecidedVBases.empty()) - return; - } - } - - // Okay, we have virtual bases that we haven't yet decided about. A - // virtual base requires a vtordisp if any the non-destructor - // virtual methods declared in this class directly override a method - // provided by that virtual base. (If so, we need to emit a thunk - // for that method, to be used in the construction vftable, which - // applies an additional 'vtordisp' this-adjustment.) - - // Collect the set of bases directly overridden by any method in this class. - // It's possible that some of these classes won't be virtual bases, or won't be - // provided by virtual bases, or won't be virtual bases in the overridden - // instance but are virtual bases elsewhere. Only the last matters for what - // we're doing, and we can ignore those: if we don't directly override - // a method provided by a virtual copy of a base class, but we do directly - // override a method provided by a non-virtual copy of that base class, - // then we must indirectly override the method provided by the virtual base, - // and so we should already have collected it in the loop above. - ClassSetTy overriddenBases; - for (CXXRecordDecl::method_iterator - M = RD->method_begin(), E = RD->method_end(); M != E; ++M) { - // Ignore non-virtual methods and destructors. - if (isa<CXXDestructorDecl>(*M) || !M->isVirtual()) - continue; - - for (CXXMethodDecl::method_iterator I = M->begin_overridden_methods(), - E = M->end_overridden_methods(); I != E; ++I) { - const CXXMethodDecl *overriddenMethod = (*I); - - // Ignore methods that override methods from vbases that require - // require vtordisps. - if (overridesMethodRequiringVtorDisp(Context, overriddenMethod)) - continue; - - // As an optimization, check immediately whether we're overriding - // something from the undecided set. - const CXXRecordDecl *overriddenBase = overriddenMethod->getParent(); - if (undecidedVBases.erase(overriddenBase)) { - vtordispVBases.insert(overriddenBase); - if (undecidedVBases.empty()) return; - - // We can't 'continue;' here because one of our undecided - // vbases might non-virtually inherit from this base. - // Consider: - // struct A { virtual void foo(); }; - // struct B : A {}; - // struct C : virtual A, virtual B { virtual void foo(); }; - // We need a vtordisp for B here. - } - - // Otherwise, just collect it. - overriddenBases.insert(overriddenBase); - } - } - - // Walk the undecided v-bases and check whether they (non-virtually) - // provide any of the overridden bases. We don't need to consider - // virtual links because the vtordisp inheres to the layout - // subobject containing the base. - for (ClassSetTy::const_iterator - I = undecidedVBases.begin(), E = undecidedVBases.end(); I != E; ++I) { - if (hasNonVirtualBaseInSet(*I, overriddenBases)) - vtordispVBases.insert(*I); - } -} - -/// hasNewVirtualFunction - Does the given polymorphic class declare a -/// virtual function that does not override a method from any of its -/// base classes? -bool -RecordLayoutBuilder::hasNewVirtualFunction(const CXXRecordDecl *RD, - bool IgnoreDestructor) const { - if (!RD->getNumBases()) - return true; - - for (CXXRecordDecl::method_iterator method = RD->method_begin(); - method != RD->method_end(); - ++method) { - if (method->isVirtual() && !method->size_overridden_methods() && - !(IgnoreDestructor && method->getKind() == Decl::CXXDestructor)) { - return true; - } - } - return false; -} - -/// isPossiblePrimaryBase - Is the given base class an acceptable -/// primary base class? -bool -RecordLayoutBuilder::isPossiblePrimaryBase(const CXXRecordDecl *base) const { - // In the Itanium ABI, a class can be a primary base class if it has - // a vtable for any reason. - if (!isMicrosoftCXXABI()) - return base->isDynamicClass(); - - // In the MS ABI, a class can only be a primary base class if it - // provides a vf-table at a static offset. That means it has to be - // non-virtual base. The existence of a separate vb-table means - // that it's possible to get virtual functions only from a virtual - // base, which we have to guard against. - - // First off, it has to have virtual functions. - if (!base->isPolymorphic()) return false; - - // If it has no virtual bases, then the vfptr must be at a static offset. - if (!base->getNumVBases()) return true; - - // Otherwise, the necessary information is cached in the layout. - const ASTRecordLayout &layout = Context.getASTRecordLayout(base); - - // If the base has its own vfptr, it can be a primary base. - if (layout.hasOwnVFPtr()) return true; - - // If the base has a primary base class, then it can be a primary base. - if (layout.getPrimaryBase()) return true; - - // Otherwise it can't. - return false; -} - void RecordLayoutBuilder::LayoutVirtualBases(const CXXRecordDecl *RD, const CXXRecordDecl *MostDerivedClass) { @@ -1466,39 +1183,7 @@ RecordLayoutBuilder::LayoutVirtualBases(const CXXRecordDecl *RD, } } -void RecordLayoutBuilder::MSLayoutVirtualBases(const CXXRecordDecl *RD) { - if (!RD->getNumVBases()) - return; - - ClassSetTy VtordispVBases; - computeVtordisps(RD, VtordispVBases); - - // This is substantially simplified because there are no virtual - // primary bases. - for (CXXRecordDecl::base_class_const_iterator I = RD->vbases_begin(), - E = RD->vbases_end(); I != E; ++I) { - const CXXRecordDecl *BaseDecl = I->getType()->getAsCXXRecordDecl(); - const BaseSubobjectInfo *BaseInfo = VirtualBaseInfo.lookup(BaseDecl); - assert(BaseInfo && "Did not find virtual base info!"); - - // If this base requires a vtordisp, add enough space for an int field. - // This is apparently always 32-bits, even on x64. - bool vtordispNeeded = false; - if (VtordispVBases.count(BaseDecl)) { - CharUnits IntSize = - CharUnits::fromQuantity(Context.getTargetInfo().getIntWidth() / 8); - - setSize(getSize() + IntSize); - setDataSize(getSize()); - vtordispNeeded = true; - } - - LayoutVirtualBase(BaseInfo, vtordispNeeded); - } -} - -void RecordLayoutBuilder::LayoutVirtualBase(const BaseSubobjectInfo *Base, - bool IsVtordispNeed) { +void RecordLayoutBuilder::LayoutVirtualBase(const BaseSubobjectInfo *Base) { assert(!Base->Derived && "Trying to lay out a primary virtual base!"); // Layout the base. @@ -1507,10 +1192,9 @@ void RecordLayoutBuilder::LayoutVirtualBase(const BaseSubobjectInfo *Base, // Add its base class offset. assert(!VBases.count(Base->Class) && "vbase offset already exists!"); VBases.insert(std::make_pair(Base->Class, - ASTRecordLayout::VBaseInfo(Offset, IsVtordispNeed))); + ASTRecordLayout::VBaseInfo(Offset, false))); - if (!isMicrosoftCXXABI()) - AddPrimaryVirtualBaseOffsets(Base, Offset); + AddPrimaryVirtualBaseOffsets(Base, Offset); } CharUnits RecordLayoutBuilder::LayoutBase(const BaseSubobjectInfo *Base) { @@ -1664,24 +1348,8 @@ void RecordLayoutBuilder::Layout(const CXXRecordDecl *RD) { Context.getTargetInfo().getCharAlign())); NonVirtualAlignment = Alignment; - if (isMicrosoftCXXABI()) { - if (NonVirtualSize != NonVirtualSize.RoundUpToAlignment(Alignment)) { - CharUnits AlignMember = - NonVirtualSize.RoundUpToAlignment(Alignment) - NonVirtualSize; - - setSize(getSize() + AlignMember); - setDataSize(getSize()); - - NonVirtualSize = Context.toCharUnitsFromBits( - llvm::RoundUpToAlignment(getSizeInBits(), - Context.getTargetInfo().getCharAlign())); - } - - MSLayoutVirtualBases(RD); - } else { - // Lay out the virtual bases and add the primary virtual base offsets. - LayoutVirtualBases(RD, RD); - } + // Lay out the virtual bases and add the primary virtual base offsets. + LayoutVirtualBases(RD, RD); // Finally, round the size of the total struct up to the alignment // of the struct itself. @@ -2100,13 +1768,6 @@ void RecordLayoutBuilder::FinishLayout(const NamedDecl *D) { return; } - - // MSVC doesn't round up to the alignment of the record with virtual bases. - if (const CXXRecordDecl *RD = dyn_cast<CXXRecordDecl>(D)) { - if (isMicrosoftCXXABI() && RD->getNumVBases()) - return; - } - // Set the size to the final size. setSize(RoundedSize); @@ -2345,11 +2006,7 @@ static bool mustSkipTailPadding(TargetCXXABI ABI, const CXXRecordDecl *RD) { } static bool isMsLayout(const RecordDecl* D) { - // FIXME: Use MS record layout for x64 code and remove MS C++ support from the - // Itanium record layout code. - return D->getASTContext().getTargetInfo().getCXXABI().isMicrosoft() && - D->getASTContext().getTargetInfo().getTriple().getArch() == - llvm::Triple::x86; + return D->getASTContext().getTargetInfo().getCXXABI().isMicrosoft(); } // This section contains an implementation of struct layout that is, up to the @@ -2363,21 +2020,25 @@ static bool isMsLayout(const RecordDecl* D) { // a non-zero length bitfield is ignored. // * The Itanium equivalent vtable pointers are split into a vfptr (virtual // function pointer) and a vbptr (virtual base pointer). They can each be -// shared with a, non-virtual bases. These bases need not be the same. vfptrs always occur at offset 0. vbptrs can occur at an +// shared with a, non-virtual bases. These bases need not be the same. vfptrs +// always occur at offset 0. vbptrs can occur at an // arbitrary offset and are placed after non-virtual bases but before fields. // * Virtual bases sometimes require a 'vtordisp' field that is laid out before // the virtual base and is used in conjunction with virtual overrides during // construction and destruction. // * vfptrs are allocated in a block of memory equal to the alignment of the -// fields and non-virtual bases at offset 0. +// fields and non-virtual bases at offset 0 in 32 bit mode and in a pointer +// sized block of memory in 64 bit mode. // * vbptrs are allocated in a block of memory equal to the alignment of the -// fields and non-virtual bases. This block is at a potentially unaligned offset. If the -// allocation slot is unaligned and the alignment is less than or equal to the -// pointer size, additional space is allocated so that the pointer can be aligned properly. This causes very strange effects on the placement of objects after the allocated block. (see -// the code). +// fields and non-virtual bases. This block is at a potentially unaligned +// offset. If the allocation slot is unaligned and the alignment is less than +// or equal to the pointer size, additional space is allocated so that the +// pointer can be aligned properly. This causes very strange effects on the +// placement of objects after the allocated block. (see the code). // * vtordisps are allocated in a block of memory with size and alignment equal // to the alignment of the completed structure (before applying __declspec( -// align())). The vtordisp always occur at the end of the allocation block, immediately prior to the virtual base. +// align())). The vtordisp always occur at the end of the allocation block, +// immediately prior to the virtual base. // * The last zero sized non-virtual base is allocated after the placement of // vbptr if one exists and can be placed at the end of the struct, potentially // aliasing either the first member or another struct allocated after this @@ -2472,7 +2133,11 @@ public: /// \brief The data alignment of the record layout. CharUnits DataSize; /// \brief The alignment of the non-virtual portion of the record layout - /// including. Only used for C++ layouts. + /// without the impact of the virtual pointers. + /// Only used for C++ layouts. + CharUnits BasesAndFieldsAlignment; + /// \brief The alignment of the non-virtual portion of the record layout + /// Only used for C++ layouts. CharUnits NonVirtualAlignment; /// \brief The additional alignment imposed by the virtual bases. CharUnits VirtualAlignment; @@ -2496,6 +2161,11 @@ public: CharUnits PointerAlignment; /// \brief Holds an empty base we haven't yet laid out. const CXXRecordDecl *LazyEmptyBase; + /// \brief Lets us know if the last base we laid out was empty. Only used + /// when adjusting the placement of a last zero-sized base in 64 bit mode. + bool LastBaseWasEmpty; + /// \brief Lets us know if we're in 64-bit mode + bool Is64BitMode; }; } // namespace @@ -2548,6 +2218,8 @@ MicrosoftRecordLayoutBuilder::getAdjustedFieldInfo(const FieldDecl *FD) { void MicrosoftRecordLayoutBuilder::initializeLayout(const RecordDecl *RD) { IsUnion = RD->isUnion(); + Is64BitMode = RD->getASTContext().getTargetInfo().getTriple().getArch() == + llvm::Triple::x86_64; Size = CharUnits::Zero(); Alignment = CharUnits::One(); @@ -2601,6 +2273,7 @@ MicrosoftRecordLayoutBuilder::initializeCXXLayout(const CXXRecordDecl *RD) { SharedVBPtrBase = 0; PrimaryBase = 0; VirtualAlignment = CharUnits::One(); + AlignAfterVBases = Is64BitMode; // 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 @@ -2638,6 +2311,7 @@ MicrosoftRecordLayoutBuilder::initializeCXXLayout(const CXXRecordDecl *RD) { // behavior correct and is not actually very expensive. layoutFields(RD); Size = CharUnits::Zero(); + BasesAndFieldsAlignment = Alignment; FieldOffsets.clear(); } @@ -2656,17 +2330,21 @@ void MicrosoftRecordLayoutBuilder::layoutVFPtr(const CXXRecordDecl *RD) { if (!HasVFPtr) return; - // MSVC potentially over-aligns the vf-table pointer by giving it - // the max alignment of all the non-virtual data in the class. The resulting - // layout is essentially { vftbl, { nvdata } }. This is completely + // MSVC 32 (but not 64) potentially over-aligns the vf-table pointer by giving + // it the max alignment of all the non-virtual data in the class. The + // resulting layout is essentially { vftbl, { nvdata } }. This is completely // unnecessary, but we're not here to pass judgment. updateAlignment(PointerAlignment); - Size += Alignment; + if (Is64BitMode) + Size = Size.RoundUpToAlignment(PointerAlignment) + PointerSize; + else + Size = Size.RoundUpToAlignment(PointerAlignment) + Alignment; } void MicrosoftRecordLayoutBuilder::layoutNonVirtualBases(const CXXRecordDecl *RD) { LazyEmptyBase = 0; + LastBaseWasEmpty = false; // Lay out the primary base first. if (PrimaryBase) @@ -2696,8 +2374,10 @@ MicrosoftRecordLayoutBuilder::layoutNonVirtualBase(const CXXRecordDecl *RD) { Size = Size.RoundUpToAlignment(LazyLayout.getAlignment()); Bases.insert(std::make_pair(LazyEmptyBase, Size)); // Empty bases only consume space when followed by another empty base. - if (RD && Layout->getNonVirtualSize().isZero()) + if (RD && Layout->getNonVirtualSize().isZero()) { + LastBaseWasEmpty = true; Size++; + } LazyEmptyBase = 0; } @@ -2716,6 +2396,7 @@ MicrosoftRecordLayoutBuilder::layoutNonVirtualBase(const CXXRecordDecl *RD) { Size = BaseOffset + Layout->getDataSize(); // Note: we don't update alignment here because it was accounted // for during initalization. + LastBaseWasEmpty = false; } void MicrosoftRecordLayoutBuilder::layoutVBPtr(const CXXRecordDecl *RD) { @@ -2725,24 +2406,24 @@ void MicrosoftRecordLayoutBuilder::layoutVBPtr(const CXXRecordDecl *RD) { const ASTRecordLayout &Layout = Context.getASTRecordLayout(SharedVBPtrBase); VBPtrOffset = Bases[SharedVBPtrBase] + Layout.getVBPtrOffset(); } else { - updateAlignment(PointerAlignment); VBPtrOffset = Size.RoundUpToAlignment(PointerAlignment); - - if (Alignment == PointerAlignment && Size % PointerAlignment) { - CharUnits x = Size + Alignment + Alignment; - Size = VBPtrOffset + Alignment; - // Handle strange padding rules. I have no explanation for why the - // virtual base is padded in such an odd way. My guess is that they - // always Add 2 * Alignment and incorrectly round down to the appropriate - // alignment. It's important to get this case correct because it impacts - // the layout of the first member of the struct. - - RecordDecl::field_iterator FieldBegin = RD->field_begin(); - if (FieldBegin != RD->field_end()) - Size += CharUnits::fromQuantity( - x % getAdjustedFieldInfo(*FieldBegin).second); - } else - Size += Alignment; + CharUnits OldSize = Size; + Size = VBPtrOffset + PointerSize; + if (BasesAndFieldsAlignment <= PointerAlignment) { + // Handle strange padding rules for the lazily placed base. I have no + // explanation for why the last virtual base is padded in such an odd way. + // Two things to note about this padding are that the rules are different + // if the alignment of the bases+fields is <= to the alignemnt of a + // pointer and that the rule in 64-bit mode behaves differently depending + // on if the second to last base was also zero sized. + Size += OldSize % BasesAndFieldsAlignment.getQuantity(); + } else { + if (Is64BitMode) + Size += LastBaseWasEmpty ? CharUnits::One() : CharUnits::Zero(); + else + Size = OldSize + BasesAndFieldsAlignment; + } + updateAlignment(PointerAlignment); } // Flush the lazy empty base. @@ -2886,10 +2567,10 @@ void MicrosoftRecordLayoutBuilder::layoutVirtualBase(const CXXRecordDecl *RD, // Empty bases only consume space when followed by another empty base. // The space consumed is in an Alignment sized/aligned block and the v-base // is placed at its alignment offset into the chunk, unless its alignment - // is less than the size of a pointer, at which it is placed at pointer - // width offset in the chunck. We have no idea why. + // is less than 4 bytes, at which it is placed at 4 byte offset in the + // chunk. We have no idea why. if (RD && Context.getASTRecordLayout(RD).getNonVirtualSize().isZero()) - Size = Size.RoundUpToAlignment(Alignment) + PointerSize; + Size = Size.RoundUpToAlignment(Alignment) + CharUnits::fromQuantity(4); LazyEmptyBase = 0; } @@ -2906,8 +2587,9 @@ void MicrosoftRecordLayoutBuilder::layoutVirtualBase(const CXXRecordDecl *RD, CharUnits BaseNVSize = Layout.getNonVirtualSize(); CharUnits BaseAlign = Layout.getAlignment(); + // vtordisps are always 4 bytes (even in 64-bit mode) if (HasVtordisp) - Size = Size.RoundUpToAlignment(Alignment) + PointerSize; + Size = Size.RoundUpToAlignment(Alignment) + CharUnits::fromQuantity(4); Size = Size.RoundUpToAlignment(BaseAlign); // Insert the base here. @@ -3091,8 +2773,8 @@ ASTContext::getASTRecordLayout(const RecordDecl *D) const { Builder.Alignment, Builder.HasOwnVFPtr, RD->isDynamicClass(), - Builder.HasOwnVBPtr, - Builder.VBPtrOffset, + false, + CharUnits::fromQuantity(-1), DataSize, Builder.FieldOffsets.data(), Builder.FieldOffsets.size(), |
