clang  6.0.0svn
MicrosoftCXXABI.cpp
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1 //===------- MicrosoftCXXABI.cpp - AST support for the Microsoft C++ ABI --===//
2 //
3 // The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 //
10 // This provides C++ AST support targeting the Microsoft Visual C++
11 // ABI.
12 //
13 //===----------------------------------------------------------------------===//
14 
15 #include "CXXABI.h"
16 #include "clang/AST/ASTContext.h"
17 #include "clang/AST/Attr.h"
18 #include "clang/AST/DeclCXX.h"
20 #include "clang/AST/RecordLayout.h"
21 #include "clang/AST/Type.h"
22 #include "clang/Basic/TargetInfo.h"
23 
24 using namespace clang;
25 
26 namespace {
27 
28 /// \brief 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;
35 
36 public:
37  MicrosoftNumberingContext()
38  : MangleNumberingContext(), LambdaManglingNumber(0),
39  StaticLocalNumber(0), StaticThreadlocalNumber(0) {}
40 
41  unsigned getManglingNumber(const CXXMethodDecl *CallOperator) override {
42  return ++LambdaManglingNumber;
43  }
44 
45  unsigned getManglingNumber(const BlockDecl *BD) override {
46  const Type *Ty = nullptr;
47  return ++ManglingNumbers[Ty];
48  }
49 
50  unsigned getStaticLocalNumber(const VarDecl *VD) override {
51  if (VD->getTLSKind())
52  return ++StaticThreadlocalNumber;
53  return ++StaticLocalNumber;
54  }
55 
56  unsigned getManglingNumber(const VarDecl *VD,
57  unsigned MSLocalManglingNumber) override {
58  return MSLocalManglingNumber;
59  }
60 
61  unsigned getManglingNumber(const TagDecl *TD,
62  unsigned MSLocalManglingNumber) override {
63  return MSLocalManglingNumber;
64  }
65 };
66 
67 class MicrosoftCXXABI : public CXXABI {
68  ASTContext &Context;
69  llvm::SmallDenseMap<CXXRecordDecl *, CXXConstructorDecl *> RecordToCopyCtor;
70 
71  llvm::SmallDenseMap<TagDecl *, DeclaratorDecl *>
72  UnnamedTagDeclToDeclaratorDecl;
73  llvm::SmallDenseMap<TagDecl *, TypedefNameDecl *>
74  UnnamedTagDeclToTypedefNameDecl;
75 
76 public:
77  MicrosoftCXXABI(ASTContext &Ctx) : Context(Ctx) { }
78 
79  MemberPointerInfo
80  getMemberPointerInfo(const MemberPointerType *MPT) const override;
81 
82  CallingConv getDefaultMethodCallConv(bool isVariadic) const override {
83  if (!isVariadic &&
84  Context.getTargetInfo().getTriple().getArch() == llvm::Triple::x86)
85  return CC_X86ThisCall;
86  return CC_C;
87  }
88 
89  bool isNearlyEmpty(const CXXRecordDecl *RD) const override {
90  llvm_unreachable("unapplicable to the MS ABI");
91  }
92 
93  const CXXConstructorDecl *
94  getCopyConstructorForExceptionObject(CXXRecordDecl *RD) override {
95  return RecordToCopyCtor[RD];
96  }
97 
98  void
99  addCopyConstructorForExceptionObject(CXXRecordDecl *RD,
100  CXXConstructorDecl *CD) override {
101  assert(CD != nullptr);
102  assert(RecordToCopyCtor[RD] == nullptr || RecordToCopyCtor[RD] == CD);
103  RecordToCopyCtor[RD] = CD;
104  }
105 
106  void addTypedefNameForUnnamedTagDecl(TagDecl *TD,
107  TypedefNameDecl *DD) override {
108  TD = TD->getCanonicalDecl();
109  DD = cast<TypedefNameDecl>(DD->getCanonicalDecl());
110  TypedefNameDecl *&I = UnnamedTagDeclToTypedefNameDecl[TD];
111  if (!I)
112  I = DD;
113  }
114 
115  TypedefNameDecl *getTypedefNameForUnnamedTagDecl(const TagDecl *TD) override {
116  return UnnamedTagDeclToTypedefNameDecl.lookup(
117  const_cast<TagDecl *>(TD->getCanonicalDecl()));
118  }
119 
120  void addDeclaratorForUnnamedTagDecl(TagDecl *TD,
121  DeclaratorDecl *DD) override {
122  TD = TD->getCanonicalDecl();
123  DD = cast<DeclaratorDecl>(DD->getCanonicalDecl());
124  DeclaratorDecl *&I = UnnamedTagDeclToDeclaratorDecl[TD];
125  if (!I)
126  I = DD;
127  }
128 
129  DeclaratorDecl *getDeclaratorForUnnamedTagDecl(const TagDecl *TD) override {
130  return UnnamedTagDeclToDeclaratorDecl.lookup(
131  const_cast<TagDecl *>(TD->getCanonicalDecl()));
132  }
133 
134  std::unique_ptr<MangleNumberingContext>
135  createMangleNumberingContext() const override {
136  return llvm::make_unique<MicrosoftNumberingContext>();
137  }
138 };
139 }
140 
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.
145  while (RD->getNumBases() > 0) {
146  if (RD->getNumBases() > 1)
147  return true;
148  assert(RD->getNumBases() == 1);
149  const CXXRecordDecl *Base =
151  if (RD->isPolymorphic() && !Base->isPolymorphic())
152  return true;
153  RD = Base;
154  }
155  return false;
156 }
157 
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;
164  return MSInheritanceAttr::Keyword_multiple_inheritance;
165  return MSInheritanceAttr::Keyword_single_inheritance;
166 }
167 
168 MSInheritanceAttr::Spelling
170  MSInheritanceAttr *IA = getAttr<MSInheritanceAttr>();
171  assert(IA && "Expected MSInheritanceAttr on the CXXRecordDecl!");
172  return IA->getSemanticSpelling();
173 }
174 
175 MSVtorDispAttr::Mode CXXRecordDecl::getMSVtorDispMode() const {
176  if (MSVtorDispAttr *VDA = getAttr<MSVtorDispAttr>())
177  return VDA->getVtorDispMode();
178  return MSVtorDispAttr::Mode(getASTContext().getLangOpts().VtorDispMode);
179 }
180 
181 // Returns the number of pointer and integer slots used to represent a member
182 // pointer in the MS C++ ABI.
183 //
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.
187 //
188 // struct {
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
191 // // slot.
192 // void *FunctionPointerOrVirtualThunk;
193 //
194 // // An offset to add to the address of the vbtable pointer after
195 // // (possibly) selecting the virtual base but before resolving and calling
196 // // the function.
197 // // Only needed if the class has any virtual bases or bases at a non-zero
198 // // offset.
199 // int NonVirtualBaseAdjustment;
200 //
201 // // The offset of the vb-table pointer within the object. Only needed for
202 // // incomplete types.
203 // int VBPtrOffset;
204 //
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;
209 // };
210 static std::pair<unsigned, unsigned>
212  const CXXRecordDecl *RD = MPT->getMostRecentCXXRecordDecl();
213  MSInheritanceAttr::Spelling Inheritance = RD->getMSInheritanceModel();
214  unsigned Ptrs = 0;
215  unsigned Ints = 0;
216  if (MPT->isMemberFunctionPointer())
217  Ptrs = 1;
218  else
219  Ints = 1;
220  if (MSInheritanceAttr::hasNVOffsetField(MPT->isMemberFunctionPointer(),
221  Inheritance))
222  Ints++;
223  if (MSInheritanceAttr::hasVBPtrOffsetField(Inheritance))
224  Ints++;
225  if (MSInheritanceAttr::hasVBTableOffsetField(Inheritance))
226  Ints++;
227  return std::make_pair(Ptrs, Ints);
228 }
229 
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();
237 
238  unsigned Ptrs, Ints;
239  std::tie(Ptrs, Ints) = getMSMemberPointerSlots(MPT);
240  MemberPointerInfo MPI;
241  MPI.HasPadding = false;
242  MPI.Width = Ptrs * PtrSize + Ints * IntSize;
243 
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
246  // function memptrs.
247  if (Ptrs + Ints > 1 && Target.getTriple().isArch32Bit())
248  MPI.Align = 64;
249  else if (Ptrs)
250  MPI.Align = Target.getPointerAlign(0);
251  else
252  MPI.Align = Target.getIntAlign();
253 
254  if (Target.getTriple().isArch64Bit()) {
255  MPI.Width = llvm::alignTo(MPI.Width, MPI.Align);
256  MPI.HasPadding = MPI.Width != (Ptrs * PtrSize + Ints * IntSize);
257  }
258  return MPI;
259 }
260 
262  return new MicrosoftCXXABI(Ctx);
263 }
264 
Defines the clang::ASTContext interface.
CXXABI * CreateMicrosoftCXXABI(ASTContext &Ctx)
if(T->getSizeExpr()) TRY_TO(TraverseStmt(T -> getSizeExpr()))
unsigned getNumBases() const
Retrieves the number of base classes of this class.
Definition: DeclCXX.h:767
const llvm::Triple & getTriple() const
Returns the target triple of the primary target.
Definition: TargetInfo.h:790
C Language Family Type Representation.
The base class of the type hierarchy.
Definition: Type.h:1353
const TargetInfo & getTargetInfo() const
Definition: ASTContext.h:671
Represents a C++ constructor within a class.
Definition: DeclCXX.h:2397
MSInheritanceAttr::Spelling getMSInheritanceModel() const
Returns the inheritance model used for this record.
VarDecl - An instance of this class is created to represent a variable declaration or definition...
Definition: Decl.h:807
MSInheritanceAttr::Spelling calculateInheritanceModel() const
Calculate what the inheritance model would be for this class.
uint64_t getPointerWidth(unsigned AddrSpace) const
Return the width of pointers on this target, for the specified address space.
Definition: TargetInfo.h:311
unsigned getIntAlign() const
Definition: TargetInfo.h:347
Holds long-lived AST nodes (such as types and decls) that can be referred to throughout the semantic ...
Definition: ASTContext.h:149
TypedefNameDecl * getCanonicalDecl() override
Retrieves the canonical declaration of this typedef-name.
Definition: Decl.h:2862
Keeps track of the mangled names of lambda expressions and block literals within a particular context...
base_class_iterator bases_begin()
Definition: DeclCXX.h:780
virtual Decl * getCanonicalDecl()
Retrieves the "canonical" declaration of the given declaration.
Definition: DeclBase.h:865
CXXRecordDecl * getAsCXXRecordDecl() const
Retrieves the CXXRecordDecl that this type refers to, either because the type is a RecordType or beca...
Definition: Type.cpp:1590
Represents a ValueDecl that came out of a declarator.
Definition: Decl.h:681
Exposes information about the current target.
Definition: TargetInfo.h:54
BlockDecl - This represents a block literal declaration, which is like an unnamed FunctionDecl...
Definition: Decl.h:3689
unsigned getIntWidth() const
getIntWidth/Align - Return the size of &#39;signed int&#39; and &#39;unsigned int&#39; for this target, in bits.
Definition: TargetInfo.h:346
TLSKind getTLSKind() const
Definition: Decl.cpp:1883
bool isPolymorphic() const
Whether this class is polymorphic (C++ [class.virtual]), which means that the class contains or inher...
Definition: DeclCXX.h:1289
static bool hasDefinition(const ObjCObjectPointerType *ObjPtr)
Implements C++ ABI-specific semantic analysis functions.
Definition: CXXABI.h:30
CallingConv
CallingConv - Specifies the calling convention that a function uses.
Definition: Specifiers.h:233
static bool usesMultipleInheritanceModel(const CXXRecordDecl *RD)
TagDecl - Represents the declaration of a struct/union/class/enum.
Definition: Decl.h:2938
TagDecl * getCanonicalDecl() override
Retrieves the "canonical" declaration of the given declaration.
Definition: Decl.cpp:3691
Represents a static or instance method of a struct/union/class.
Definition: DeclCXX.h:1964
MSVtorDispAttr::Mode getMSVtorDispMode() const
Controls when vtordisps will be emitted if this record is used as a virtual base. ...
Base class for declarations which introduce a typedef-name.
Definition: Decl.h:2796
CXXRecordDecl * getMostRecentCXXRecordDecl() const
Definition: Type.cpp:3908
Dataflow Directional Tag Classes.
A pointer to member type per C++ 8.3.3 - Pointers to members.
Definition: Type.h:2504
Defines the C++ Decl subclasses, other than those for templates (found in DeclTemplate.h) and friends (in DeclFriend.h).
Represents a C++ struct/union/class.
Definition: DeclCXX.h:299
bool isMemberFunctionPointer() const
Returns true if the member type (i.e.
Definition: Type.h:2528
uint64_t getPointerAlign(unsigned AddrSpace) const
Definition: TargetInfo.h:314
Defines the clang::TargetInfo interface.
static std::pair< unsigned, unsigned > getMSMemberPointerSlots(const MemberPointerType *MPT)
QualType getType() const
Retrieves the type of the base class.
Definition: DeclCXX.h:290