1 //===------- MicrosoftCXXABI.cpp - AST support for the Microsoft C++ ABI --===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This provides C++ AST support targeting the Microsoft Visual C++
13 //===----------------------------------------------------------------------===//
16 #include "clang/AST/ASTContext.h"
17 #include "clang/AST/Attr.h"
18 #include "clang/AST/DeclCXX.h"
19 #include "clang/AST/MangleNumberingContext.h"
20 #include "clang/AST/RecordLayout.h"
21 #include "clang/AST/Type.h"
22 #include "clang/Basic/TargetInfo.h"
24 using namespace clang;
28 /// Numbers things which need to correspond across multiple TUs.
29 /// Typically these are things like static locals, lambdas, or blocks.
30 class MicrosoftNumberingContext : public MangleNumberingContext {
31 llvm::DenseMap<const Type *, unsigned> ManglingNumbers;
32 unsigned LambdaManglingNumber;
33 unsigned StaticLocalNumber;
34 unsigned StaticThreadlocalNumber;
37 MicrosoftNumberingContext()
38 : MangleNumberingContext(), LambdaManglingNumber(0),
39 StaticLocalNumber(0), StaticThreadlocalNumber(0) {}
41 unsigned getManglingNumber(const CXXMethodDecl *CallOperator) override {
42 return ++LambdaManglingNumber;
45 unsigned getManglingNumber(const BlockDecl *BD) override {
46 const Type *Ty = nullptr;
47 return ++ManglingNumbers[Ty];
50 unsigned getStaticLocalNumber(const VarDecl *VD) override {
52 return ++StaticThreadlocalNumber;
53 return ++StaticLocalNumber;
56 unsigned getManglingNumber(const VarDecl *VD,
57 unsigned MSLocalManglingNumber) override {
58 return MSLocalManglingNumber;
61 unsigned getManglingNumber(const TagDecl *TD,
62 unsigned MSLocalManglingNumber) override {
63 return MSLocalManglingNumber;
67 class MicrosoftCXXABI : public CXXABI {
69 llvm::SmallDenseMap<CXXRecordDecl *, CXXConstructorDecl *> RecordToCopyCtor;
71 llvm::SmallDenseMap<TagDecl *, DeclaratorDecl *>
72 UnnamedTagDeclToDeclaratorDecl;
73 llvm::SmallDenseMap<TagDecl *, TypedefNameDecl *>
74 UnnamedTagDeclToTypedefNameDecl;
77 MicrosoftCXXABI(ASTContext &Ctx) : Context(Ctx) { }
80 getMemberPointerInfo(const MemberPointerType *MPT) const override;
82 CallingConv getDefaultMethodCallConv(bool isVariadic) const override {
84 Context.getTargetInfo().getTriple().getArch() == llvm::Triple::x86)
85 return CC_X86ThisCall;
89 bool isNearlyEmpty(const CXXRecordDecl *RD) const override {
90 llvm_unreachable("unapplicable to the MS ABI");
93 const CXXConstructorDecl *
94 getCopyConstructorForExceptionObject(CXXRecordDecl *RD) override {
95 return RecordToCopyCtor[RD];
99 addCopyConstructorForExceptionObject(CXXRecordDecl *RD,
100 CXXConstructorDecl *CD) override {
101 assert(CD != nullptr);
102 assert(RecordToCopyCtor[RD] == nullptr || RecordToCopyCtor[RD] == CD);
103 RecordToCopyCtor[RD] = CD;
106 void addTypedefNameForUnnamedTagDecl(TagDecl *TD,
107 TypedefNameDecl *DD) override {
108 TD = TD->getCanonicalDecl();
109 DD = DD->getCanonicalDecl();
110 TypedefNameDecl *&I = UnnamedTagDeclToTypedefNameDecl[TD];
115 TypedefNameDecl *getTypedefNameForUnnamedTagDecl(const TagDecl *TD) override {
116 return UnnamedTagDeclToTypedefNameDecl.lookup(
117 const_cast<TagDecl *>(TD->getCanonicalDecl()));
120 void addDeclaratorForUnnamedTagDecl(TagDecl *TD,
121 DeclaratorDecl *DD) override {
122 TD = TD->getCanonicalDecl();
123 DD = cast<DeclaratorDecl>(DD->getCanonicalDecl());
124 DeclaratorDecl *&I = UnnamedTagDeclToDeclaratorDecl[TD];
129 DeclaratorDecl *getDeclaratorForUnnamedTagDecl(const TagDecl *TD) override {
130 return UnnamedTagDeclToDeclaratorDecl.lookup(
131 const_cast<TagDecl *>(TD->getCanonicalDecl()));
134 std::unique_ptr<MangleNumberingContext>
135 createMangleNumberingContext() const override {
136 return llvm::make_unique<MicrosoftNumberingContext>();
141 // getNumBases() seems to only give us the number of direct bases, and not the
142 // total. This function tells us if we inherit from anybody that uses MI, or if
143 // we have a non-primary base class, which uses the multiple inheritance model.
144 static bool usesMultipleInheritanceModel(const CXXRecordDecl *RD) {
145 while (RD->getNumBases() > 0) {
146 if (RD->getNumBases() > 1)
148 assert(RD->getNumBases() == 1);
149 const CXXRecordDecl *Base =
150 RD->bases_begin()->getType()->getAsCXXRecordDecl();
151 if (RD->isPolymorphic() && !Base->isPolymorphic())
158 MSInheritanceAttr::Spelling CXXRecordDecl::calculateInheritanceModel() const {
159 if (!hasDefinition() || isParsingBaseSpecifiers())
160 return MSInheritanceAttr::Keyword_unspecified_inheritance;
161 if (getNumVBases() > 0)
162 return MSInheritanceAttr::Keyword_virtual_inheritance;
163 if (usesMultipleInheritanceModel(this))
164 return MSInheritanceAttr::Keyword_multiple_inheritance;
165 return MSInheritanceAttr::Keyword_single_inheritance;
168 MSInheritanceAttr::Spelling
169 CXXRecordDecl::getMSInheritanceModel() const {
170 MSInheritanceAttr *IA = getAttr<MSInheritanceAttr>();
171 assert(IA && "Expected MSInheritanceAttr on the CXXRecordDecl!");
172 return IA->getSemanticSpelling();
175 MSVtorDispAttr::Mode CXXRecordDecl::getMSVtorDispMode() const {
176 if (MSVtorDispAttr *VDA = getAttr<MSVtorDispAttr>())
177 return VDA->getVtorDispMode();
178 return MSVtorDispAttr::Mode(getASTContext().getLangOpts().VtorDispMode);
181 // Returns the number of pointer and integer slots used to represent a member
182 // pointer in the MS C++ ABI.
184 // Member function pointers have the following general form; however, fields
185 // are dropped as permitted (under the MSVC interpretation) by the inheritance
186 // model of the actual class.
189 // // A pointer to the member function to call. If the member function is
190 // // virtual, this will be a thunk that forwards to the appropriate vftable
192 // void *FunctionPointerOrVirtualThunk;
194 // // An offset to add to the address of the vbtable pointer after
195 // // (possibly) selecting the virtual base but before resolving and calling
197 // // Only needed if the class has any virtual bases or bases at a non-zero
199 // int NonVirtualBaseAdjustment;
201 // // The offset of the vb-table pointer within the object. Only needed for
202 // // incomplete types.
205 // // An offset within the vb-table that selects the virtual base containing
206 // // the member. Loading from this offset produces a new offset that is
207 // // added to the address of the vb-table pointer to produce the base.
208 // int VirtualBaseAdjustmentOffset;
210 static std::pair<unsigned, unsigned>
211 getMSMemberPointerSlots(const MemberPointerType *MPT) {
212 const CXXRecordDecl *RD = MPT->getMostRecentCXXRecordDecl();
213 MSInheritanceAttr::Spelling Inheritance = RD->getMSInheritanceModel();
216 if (MPT->isMemberFunctionPointer())
220 if (MSInheritanceAttr::hasNVOffsetField(MPT->isMemberFunctionPointer(),
223 if (MSInheritanceAttr::hasVBPtrOffsetField(Inheritance))
225 if (MSInheritanceAttr::hasVBTableOffsetField(Inheritance))
227 return std::make_pair(Ptrs, Ints);
230 CXXABI::MemberPointerInfo MicrosoftCXXABI::getMemberPointerInfo(
231 const MemberPointerType *MPT) const {
232 // The nominal struct is laid out with pointers followed by ints and aligned
233 // to a pointer width if any are present and an int width otherwise.
234 const TargetInfo &Target = Context.getTargetInfo();
235 unsigned PtrSize = Target.getPointerWidth(0);
236 unsigned IntSize = Target.getIntWidth();
239 std::tie(Ptrs, Ints) = getMSMemberPointerSlots(MPT);
240 MemberPointerInfo MPI;
241 MPI.HasPadding = false;
242 MPI.Width = Ptrs * PtrSize + Ints * IntSize;
244 // When MSVC does x86_32 record layout, it aligns aggregate member pointers to
245 // 8 bytes. However, __alignof usually returns 4 for data memptrs and 8 for
247 if (Ptrs + Ints > 1 && Target.getTriple().isArch32Bit())
250 MPI.Align = Target.getPointerAlign(0);
252 MPI.Align = Target.getIntAlign();
254 if (Target.getTriple().isArch64Bit()) {
255 MPI.Width = llvm::alignTo(MPI.Width, MPI.Align);
256 MPI.HasPadding = MPI.Width != (Ptrs * PtrSize + Ints * IntSize);
261 CXXABI *clang::CreateMicrosoftCXXABI(ASTContext &Ctx) {
262 return new MicrosoftCXXABI(Ctx);