| //===------- MicrosoftCXXABI.cpp - AST support for the Microsoft C++ ABI --===// |
| // |
| // The LLVM Compiler Infrastructure |
| // |
| // This file is distributed under the University of Illinois Open Source |
| // License. See LICENSE.TXT for details. |
| // |
| //===----------------------------------------------------------------------===// |
| // |
| // This provides C++ AST support targeting the Microsoft Visual C++ |
| // ABI. |
| // |
| //===----------------------------------------------------------------------===// |
| |
| #include "CXXABI.h" |
| #include "clang/AST/ASTContext.h" |
| #include "clang/AST/Attr.h" |
| #include "clang/AST/DeclCXX.h" |
| #include "clang/AST/MangleNumberingContext.h" |
| #include "clang/AST/RecordLayout.h" |
| #include "clang/AST/Type.h" |
| #include "clang/Basic/TargetInfo.h" |
| |
| using namespace clang; |
| |
| namespace { |
| |
| /// \brief Numbers things which need to correspond across multiple TUs. |
| /// Typically these are things like static locals, lambdas, or blocks. |
| class MicrosoftNumberingContext : public MangleNumberingContext { |
| public: |
| unsigned getManglingNumber(const VarDecl *VD, |
| unsigned MSLocalManglingNumber) override { |
| return MSLocalManglingNumber; |
| } |
| |
| unsigned getManglingNumber(const TagDecl *TD, |
| unsigned MSLocalManglingNumber) override { |
| return MSLocalManglingNumber; |
| } |
| }; |
| |
| class MicrosoftCXXABI : public CXXABI { |
| ASTContext &Context; |
| public: |
| MicrosoftCXXABI(ASTContext &Ctx) : Context(Ctx) { } |
| |
| std::pair<uint64_t, unsigned> |
| getMemberPointerWidthAndAlign(const MemberPointerType *MPT) const override; |
| |
| CallingConv getDefaultMethodCallConv(bool isVariadic) const override { |
| if (!isVariadic && |
| Context.getTargetInfo().getTriple().getArch() == llvm::Triple::x86) |
| return CC_X86ThisCall; |
| return CC_C; |
| } |
| |
| bool isNearlyEmpty(const CXXRecordDecl *RD) const override { |
| // FIXME: Audit the corners |
| if (!RD->isDynamicClass()) |
| return false; |
| |
| const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD); |
| |
| // In the Microsoft ABI, classes can have one or two vtable pointers. |
| CharUnits PointerSize = |
| Context.toCharUnitsFromBits(Context.getTargetInfo().getPointerWidth(0)); |
| return Layout.getNonVirtualSize() == PointerSize || |
| Layout.getNonVirtualSize() == PointerSize * 2; |
| } |
| |
| MangleNumberingContext *createMangleNumberingContext() const override { |
| return new MicrosoftNumberingContext(); |
| } |
| }; |
| } |
| |
| // getNumBases() seems to only give us the number of direct bases, and not the |
| // total. This function tells us if we inherit from anybody that uses MI, or if |
| // we have a non-primary base class, which uses the multiple inheritance model. |
| static bool usesMultipleInheritanceModel(const CXXRecordDecl *RD) { |
| while (RD->getNumBases() > 0) { |
| if (RD->getNumBases() > 1) |
| return true; |
| assert(RD->getNumBases() == 1); |
| const CXXRecordDecl *Base = |
| RD->bases_begin()->getType()->getAsCXXRecordDecl(); |
| if (RD->isPolymorphic() && !Base->isPolymorphic()) |
| return true; |
| RD = Base; |
| } |
| return false; |
| } |
| |
| MSInheritanceAttr::Spelling CXXRecordDecl::calculateInheritanceModel() const { |
| if (!hasDefinition() || isParsingBaseSpecifiers()) |
| return MSInheritanceAttr::Keyword_unspecified_inheritance; |
| if (getNumVBases() > 0) |
| return MSInheritanceAttr::Keyword_virtual_inheritance; |
| if (usesMultipleInheritanceModel(this)) |
| return MSInheritanceAttr::Keyword_multiple_inheritance; |
| return MSInheritanceAttr::Keyword_single_inheritance; |
| } |
| |
| MSInheritanceAttr::Spelling |
| CXXRecordDecl::getMSInheritanceModel() const { |
| MSInheritanceAttr *IA = getAttr<MSInheritanceAttr>(); |
| assert(IA && "Expected MSInheritanceAttr on the CXXRecordDecl!"); |
| return IA->getSemanticSpelling(); |
| } |
| |
| MSVtorDispAttr::Mode CXXRecordDecl::getMSVtorDispMode() const { |
| if (MSVtorDispAttr *VDA = getAttr<MSVtorDispAttr>()) |
| return VDA->getVtorDispMode(); |
| return MSVtorDispAttr::Mode(getASTContext().getLangOpts().VtorDispMode); |
| } |
| |
| // Returns the number of pointer and integer slots used to represent a member |
| // pointer in the MS C++ ABI. |
| // |
| // Member function pointers have the following general form; however, fields |
| // are dropped as permitted (under the MSVC interpretation) by the inheritance |
| // model of the actual class. |
| // |
| // struct { |
| // // A pointer to the member function to call. If the member function is |
| // // virtual, this will be a thunk that forwards to the appropriate vftable |
| // // slot. |
| // void *FunctionPointerOrVirtualThunk; |
| // |
| // // An offset to add to the address of the vbtable pointer after (possibly) |
| // // selecting the virtual base but before resolving and calling the function. |
| // // Only needed if the class has any virtual bases or bases at a non-zero |
| // // offset. |
| // int NonVirtualBaseAdjustment; |
| // |
| // // The offset of the vb-table pointer within the object. Only needed for |
| // // incomplete types. |
| // int VBPtrOffset; |
| // |
| // // An offset within the vb-table that selects the virtual base containing |
| // // the member. Loading from this offset produces a new offset that is |
| // // added to the address of the vb-table pointer to produce the base. |
| // int VirtualBaseAdjustmentOffset; |
| // }; |
| static std::pair<unsigned, unsigned> |
| getMSMemberPointerSlots(const MemberPointerType *MPT) { |
| const CXXRecordDecl *RD = MPT->getMostRecentCXXRecordDecl(); |
| MSInheritanceAttr::Spelling Inheritance = RD->getMSInheritanceModel(); |
| unsigned Ptrs = 0; |
| unsigned Ints = 0; |
| if (MPT->isMemberFunctionPointer()) |
| Ptrs = 1; |
| else |
| Ints = 1; |
| if (MSInheritanceAttr::hasNVOffsetField(MPT->isMemberFunctionPointer(), |
| Inheritance)) |
| Ints++; |
| if (MSInheritanceAttr::hasVBPtrOffsetField(Inheritance)) |
| Ints++; |
| if (MSInheritanceAttr::hasVBTableOffsetField(Inheritance)) |
| Ints++; |
| return std::make_pair(Ptrs, Ints); |
| } |
| |
| std::pair<uint64_t, unsigned> MicrosoftCXXABI::getMemberPointerWidthAndAlign( |
| const MemberPointerType *MPT) const { |
| const TargetInfo &Target = Context.getTargetInfo(); |
| assert(Target.getTriple().getArch() == llvm::Triple::x86 || |
| Target.getTriple().getArch() == llvm::Triple::x86_64); |
| unsigned Ptrs, Ints; |
| std::tie(Ptrs, Ints) = getMSMemberPointerSlots(MPT); |
| // The nominal struct is laid out with pointers followed by ints and aligned |
| // to a pointer width if any are present and an int width otherwise. |
| unsigned PtrSize = Target.getPointerWidth(0); |
| unsigned IntSize = Target.getIntWidth(); |
| uint64_t Width = Ptrs * PtrSize + Ints * IntSize; |
| unsigned Align; |
| |
| // When MSVC does x86_32 record layout, it aligns aggregate member pointers to |
| // 8 bytes. However, __alignof usually returns 4 for data memptrs and 8 for |
| // function memptrs. |
| if (Ptrs + Ints > 1 && Target.getTriple().getArch() == llvm::Triple::x86) |
| Align = 8 * 8; |
| else if (Ptrs) |
| Align = Target.getPointerAlign(0); |
| else |
| Align = Target.getIntAlign(); |
| |
| if (Target.getTriple().getArch() == llvm::Triple::x86_64) |
| Width = llvm::RoundUpToAlignment(Width, Align); |
| return std::make_pair(Width, Align); |
| } |
| |
| CXXABI *clang::CreateMicrosoftCXXABI(ASTContext &Ctx) { |
| return new MicrosoftCXXABI(Ctx); |
| } |
| |