1 //===----- CGCXXABI.h - Interface to C++ ABIs -------------------*- C++ -*-===//
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 an abstract class for C++ code generation. Concrete subclasses
11 // of this implement code generation for specific C++ ABIs.
12 //
13 //===----------------------------------------------------------------------===//
14 
15 #ifndef LLVM_CLANG_LIB_CODEGEN_CGCXXABI_H
16 #define LLVM_CLANG_LIB_CODEGEN_CGCXXABI_H
17 
18 #include "CodeGenFunction.h"
19 #include "clang/Basic/LLVM.h"
20 
21 namespace llvm {
22 class Constant;
23 class Type;
24 class Value;
25 class CallInst;
26 }
27 
28 namespace clang {
29 class CastExpr;
30 class CXXConstructorDecl;
31 class CXXDestructorDecl;
32 class CXXMethodDecl;
33 class CXXRecordDecl;
34 class FieldDecl;
35 class MangleContext;
36 
37 namespace CodeGen {
38 class CodeGenFunction;
39 class CodeGenModule;
40 struct CatchTypeInfo;
41 
42 /// \brief Implements C++ ABI-specific code generation functions.
43 class CGCXXABI {
44 protected:
45   CodeGenModule &CGM;
46   std::unique_ptr<MangleContext> MangleCtx;
47 
CGCXXABI(CodeGenModule & CGM)48   CGCXXABI(CodeGenModule &CGM)
49     : CGM(CGM), MangleCtx(CGM.getContext().createMangleContext()) {}
50 
51 protected:
getThisDecl(CodeGenFunction & CGF)52   ImplicitParamDecl *getThisDecl(CodeGenFunction &CGF) {
53     return CGF.CXXABIThisDecl;
54   }
getThisValue(CodeGenFunction & CGF)55   llvm::Value *getThisValue(CodeGenFunction &CGF) {
56     return CGF.CXXABIThisValue;
57   }
getThisAddress(CodeGenFunction & CGF)58   Address getThisAddress(CodeGenFunction &CGF) {
59     return Address(CGF.CXXABIThisValue, CGF.CXXABIThisAlignment);
60   }
61 
62   /// Issue a diagnostic about unsupported features in the ABI.
63   void ErrorUnsupportedABI(CodeGenFunction &CGF, StringRef S);
64 
65   /// Get a null value for unsupported member pointers.
66   llvm::Constant *GetBogusMemberPointer(QualType T);
67 
getStructorImplicitParamDecl(CodeGenFunction & CGF)68   ImplicitParamDecl *&getStructorImplicitParamDecl(CodeGenFunction &CGF) {
69     return CGF.CXXStructorImplicitParamDecl;
70   }
getStructorImplicitParamValue(CodeGenFunction & CGF)71   llvm::Value *&getStructorImplicitParamValue(CodeGenFunction &CGF) {
72     return CGF.CXXStructorImplicitParamValue;
73   }
74 
75   /// Perform prolog initialization of the parameter variable suitable
76   /// for 'this' emitted by buildThisParam.
77   void EmitThisParam(CodeGenFunction &CGF);
78 
getContext()79   ASTContext &getContext() const { return CGM.getContext(); }
80 
81   virtual bool requiresArrayCookie(const CXXDeleteExpr *E, QualType eltType);
82   virtual bool requiresArrayCookie(const CXXNewExpr *E);
83 
84   /// Determine whether there's something special about the rules of
85   /// the ABI tell us that 'this' is a complete object within the
86   /// given function.  Obvious common logic like being defined on a
87   /// final class will have been taken care of by the caller.
88   virtual bool isThisCompleteObject(GlobalDecl GD) const = 0;
89 
90 public:
91 
92   virtual ~CGCXXABI();
93 
94   /// Gets the mangle context.
getMangleContext()95   MangleContext &getMangleContext() {
96     return *MangleCtx;
97   }
98 
99   /// Returns true if the given constructor or destructor is one of the
100   /// kinds that the ABI says returns 'this' (only applies when called
101   /// non-virtually for destructors).
102   ///
103   /// There currently is no way to indicate if a destructor returns 'this'
104   /// when called virtually, and code generation does not support the case.
HasThisReturn(GlobalDecl GD)105   virtual bool HasThisReturn(GlobalDecl GD) const { return false; }
106 
hasMostDerivedReturn(GlobalDecl GD)107   virtual bool hasMostDerivedReturn(GlobalDecl GD) const { return false; }
108 
109   /// If the C++ ABI requires the given type be returned in a particular way,
110   /// this method sets RetAI and returns true.
111   virtual bool classifyReturnType(CGFunctionInfo &FI) const = 0;
112 
113   /// Specify how one should pass an argument of a record type.
114   enum RecordArgABI {
115     /// Pass it using the normal C aggregate rules for the ABI, potentially
116     /// introducing extra copies and passing some or all of it in registers.
117     RAA_Default = 0,
118 
119     /// Pass it on the stack using its defined layout.  The argument must be
120     /// evaluated directly into the correct stack position in the arguments area,
121     /// and the call machinery must not move it or introduce extra copies.
122     RAA_DirectInMemory,
123 
124     /// Pass it as a pointer to temporary memory.
125     RAA_Indirect
126   };
127 
128   /// Returns true if C++ allows us to copy the memory of an object of type RD
129   /// when it is passed as an argument.
130   bool canCopyArgument(const CXXRecordDecl *RD) const;
131 
132   /// Returns how an argument of the given record type should be passed.
133   virtual RecordArgABI getRecordArgABI(const CXXRecordDecl *RD) const = 0;
134 
135   /// Returns true if the implicit 'sret' parameter comes after the implicit
136   /// 'this' parameter of C++ instance methods.
isSRetParameterAfterThis()137   virtual bool isSRetParameterAfterThis() const { return false; }
138 
139   /// Find the LLVM type used to represent the given member pointer
140   /// type.
141   virtual llvm::Type *
142   ConvertMemberPointerType(const MemberPointerType *MPT);
143 
144   /// Load a member function from an object and a member function
145   /// pointer.  Apply the this-adjustment and set 'This' to the
146   /// adjusted value.
147   virtual llvm::Value *EmitLoadOfMemberFunctionPointer(
148       CodeGenFunction &CGF, const Expr *E, Address This,
149       llvm::Value *&ThisPtrForCall, llvm::Value *MemPtr,
150       const MemberPointerType *MPT);
151 
152   /// Calculate an l-value from an object and a data member pointer.
153   virtual llvm::Value *
154   EmitMemberDataPointerAddress(CodeGenFunction &CGF, const Expr *E,
155                                Address Base, llvm::Value *MemPtr,
156                                const MemberPointerType *MPT);
157 
158   /// Perform a derived-to-base, base-to-derived, or bitcast member
159   /// pointer conversion.
160   virtual llvm::Value *EmitMemberPointerConversion(CodeGenFunction &CGF,
161                                                    const CastExpr *E,
162                                                    llvm::Value *Src);
163 
164   /// Perform a derived-to-base, base-to-derived, or bitcast member
165   /// pointer conversion on a constant value.
166   virtual llvm::Constant *EmitMemberPointerConversion(const CastExpr *E,
167                                                       llvm::Constant *Src);
168 
169   /// Return true if the given member pointer can be zero-initialized
170   /// (in the C++ sense) with an LLVM zeroinitializer.
171   virtual bool isZeroInitializable(const MemberPointerType *MPT);
172 
173   /// Return whether or not a member pointers type is convertible to an IR type.
isMemberPointerConvertible(const MemberPointerType * MPT)174   virtual bool isMemberPointerConvertible(const MemberPointerType *MPT) const {
175     return true;
176   }
177 
178   /// Create a null member pointer of the given type.
179   virtual llvm::Constant *EmitNullMemberPointer(const MemberPointerType *MPT);
180 
181   /// Create a member pointer for the given method.
182   virtual llvm::Constant *EmitMemberFunctionPointer(const CXXMethodDecl *MD);
183 
184   /// Create a member pointer for the given field.
185   virtual llvm::Constant *EmitMemberDataPointer(const MemberPointerType *MPT,
186                                                 CharUnits offset);
187 
188   /// Create a member pointer for the given member pointer constant.
189   virtual llvm::Constant *EmitMemberPointer(const APValue &MP, QualType MPT);
190 
191   /// Emit a comparison between two member pointers.  Returns an i1.
192   virtual llvm::Value *
193   EmitMemberPointerComparison(CodeGenFunction &CGF,
194                               llvm::Value *L,
195                               llvm::Value *R,
196                               const MemberPointerType *MPT,
197                               bool Inequality);
198 
199   /// Determine if a member pointer is non-null.  Returns an i1.
200   virtual llvm::Value *
201   EmitMemberPointerIsNotNull(CodeGenFunction &CGF,
202                              llvm::Value *MemPtr,
203                              const MemberPointerType *MPT);
204 
205 protected:
206   /// A utility method for computing the offset required for the given
207   /// base-to-derived or derived-to-base member-pointer conversion.
208   /// Does not handle virtual conversions (in case we ever fully
209   /// support an ABI that allows this).  Returns null if no adjustment
210   /// is required.
211   llvm::Constant *getMemberPointerAdjustment(const CastExpr *E);
212 
213   /// \brief Computes the non-virtual adjustment needed for a member pointer
214   /// conversion along an inheritance path stored in an APValue.  Unlike
215   /// getMemberPointerAdjustment(), the adjustment can be negative if the path
216   /// is from a derived type to a base type.
217   CharUnits getMemberPointerPathAdjustment(const APValue &MP);
218 
219 public:
220   virtual void emitVirtualObjectDelete(CodeGenFunction &CGF,
221                                        const CXXDeleteExpr *DE,
222                                        Address Ptr, QualType ElementType,
223                                        const CXXDestructorDecl *Dtor) = 0;
224   virtual void emitRethrow(CodeGenFunction &CGF, bool isNoReturn) = 0;
225   virtual void emitThrow(CodeGenFunction &CGF, const CXXThrowExpr *E) = 0;
getThrowInfo(QualType T)226   virtual llvm::GlobalVariable *getThrowInfo(QualType T) { return nullptr; }
227 
228   /// \brief Determine whether it's possible to emit a vtable for \p RD, even
229   /// though we do not know that the vtable has been marked as used by semantic
230   /// analysis.
231   virtual bool canSpeculativelyEmitVTable(const CXXRecordDecl *RD) const = 0;
232 
233   virtual void emitBeginCatch(CodeGenFunction &CGF, const CXXCatchStmt *C) = 0;
234 
235   virtual llvm::CallInst *
236   emitTerminateForUnexpectedException(CodeGenFunction &CGF,
237                                       llvm::Value *Exn);
238 
239   virtual llvm::Constant *getAddrOfRTTIDescriptor(QualType Ty) = 0;
240   virtual CatchTypeInfo
241   getAddrOfCXXCatchHandlerType(QualType Ty, QualType CatchHandlerType) = 0;
242   virtual CatchTypeInfo getCatchAllTypeInfo();
243 
244   virtual bool shouldTypeidBeNullChecked(bool IsDeref,
245                                          QualType SrcRecordTy) = 0;
246   virtual void EmitBadTypeidCall(CodeGenFunction &CGF) = 0;
247   virtual llvm::Value *EmitTypeid(CodeGenFunction &CGF, QualType SrcRecordTy,
248                                   Address ThisPtr,
249                                   llvm::Type *StdTypeInfoPtrTy) = 0;
250 
251   virtual bool shouldDynamicCastCallBeNullChecked(bool SrcIsPtr,
252                                                   QualType SrcRecordTy) = 0;
253 
254   virtual llvm::Value *
255   EmitDynamicCastCall(CodeGenFunction &CGF, Address Value,
256                       QualType SrcRecordTy, QualType DestTy,
257                       QualType DestRecordTy, llvm::BasicBlock *CastEnd) = 0;
258 
259   virtual llvm::Value *EmitDynamicCastToVoid(CodeGenFunction &CGF,
260                                              Address Value,
261                                              QualType SrcRecordTy,
262                                              QualType DestTy) = 0;
263 
264   virtual bool EmitBadCastCall(CodeGenFunction &CGF) = 0;
265 
266   virtual llvm::Value *GetVirtualBaseClassOffset(CodeGenFunction &CGF,
267                                                  Address This,
268                                                  const CXXRecordDecl *ClassDecl,
269                                         const CXXRecordDecl *BaseClassDecl) = 0;
270 
271   virtual llvm::BasicBlock *EmitCtorCompleteObjectHandler(CodeGenFunction &CGF,
272                                                           const CXXRecordDecl *RD);
273 
274   /// Emit the code to initialize hidden members required
275   /// to handle virtual inheritance, if needed by the ABI.
276   virtual void
initializeHiddenVirtualInheritanceMembers(CodeGenFunction & CGF,const CXXRecordDecl * RD)277   initializeHiddenVirtualInheritanceMembers(CodeGenFunction &CGF,
278                                             const CXXRecordDecl *RD) {}
279 
280   /// Emit constructor variants required by this ABI.
281   virtual void EmitCXXConstructors(const CXXConstructorDecl *D) = 0;
282 
283   /// Build the signature of the given constructor or destructor variant by
284   /// adding any required parameters.  For convenience, ArgTys has been
285   /// initialized with the type of 'this'.
286   virtual void buildStructorSignature(const CXXMethodDecl *MD, StructorType T,
287                                       SmallVectorImpl<CanQualType> &ArgTys) = 0;
288 
289   /// Returns true if the given destructor type should be emitted as a linkonce
290   /// delegating thunk, regardless of whether the dtor is defined in this TU or
291   /// not.
292   virtual bool useThunkForDtorVariant(const CXXDestructorDecl *Dtor,
293                                       CXXDtorType DT) const = 0;
294 
295   /// Emit destructor variants required by this ABI.
296   virtual void EmitCXXDestructors(const CXXDestructorDecl *D) = 0;
297 
298   /// Get the type of the implicit "this" parameter used by a method. May return
299   /// zero if no specific type is applicable, e.g. if the ABI expects the "this"
300   /// parameter to point to some artificial offset in a complete object due to
301   /// vbases being reordered.
302   virtual const CXXRecordDecl *
getThisArgumentTypeForMethod(const CXXMethodDecl * MD)303   getThisArgumentTypeForMethod(const CXXMethodDecl *MD) {
304     return MD->getParent();
305   }
306 
307   /// Perform ABI-specific "this" argument adjustment required prior to
308   /// a call of a virtual function.
309   /// The "VirtualCall" argument is true iff the call itself is virtual.
310   virtual Address
adjustThisArgumentForVirtualFunctionCall(CodeGenFunction & CGF,GlobalDecl GD,Address This,bool VirtualCall)311   adjustThisArgumentForVirtualFunctionCall(CodeGenFunction &CGF, GlobalDecl GD,
312                                            Address This, bool VirtualCall) {
313     return This;
314   }
315 
316   /// Build a parameter variable suitable for 'this'.
317   void buildThisParam(CodeGenFunction &CGF, FunctionArgList &Params);
318 
319   /// Insert any ABI-specific implicit parameters into the parameter list for a
320   /// function.  This generally involves extra data for constructors and
321   /// destructors.
322   ///
323   /// ABIs may also choose to override the return type, which has been
324   /// initialized with the type of 'this' if HasThisReturn(CGF.CurGD) is true or
325   /// the formal return type of the function otherwise.
326   virtual void addImplicitStructorParams(CodeGenFunction &CGF, QualType &ResTy,
327                                          FunctionArgList &Params) = 0;
328 
329   /// Perform ABI-specific "this" parameter adjustment in a virtual function
330   /// prologue.
adjustThisParameterInVirtualFunctionPrologue(CodeGenFunction & CGF,GlobalDecl GD,llvm::Value * This)331   virtual llvm::Value *adjustThisParameterInVirtualFunctionPrologue(
332       CodeGenFunction &CGF, GlobalDecl GD, llvm::Value *This) {
333     return This;
334   }
335 
336   /// Emit the ABI-specific prolog for the function.
337   virtual void EmitInstanceFunctionProlog(CodeGenFunction &CGF) = 0;
338 
339   /// Add any ABI-specific implicit arguments needed to call a constructor.
340   ///
341   /// \return The number of args added to the call, which is typically zero or
342   /// one.
343   virtual unsigned
344   addImplicitConstructorArgs(CodeGenFunction &CGF, const CXXConstructorDecl *D,
345                              CXXCtorType Type, bool ForVirtualBase,
346                              bool Delegating, CallArgList &Args) = 0;
347 
348   /// Emit the destructor call.
349   virtual void EmitDestructorCall(CodeGenFunction &CGF,
350                                   const CXXDestructorDecl *DD, CXXDtorType Type,
351                                   bool ForVirtualBase, bool Delegating,
352                                   Address This) = 0;
353 
354   /// Emits the VTable definitions required for the given record type.
355   virtual void emitVTableDefinitions(CodeGenVTables &CGVT,
356                                      const CXXRecordDecl *RD) = 0;
357 
358   /// Checks if ABI requires extra virtual offset for vtable field.
359   virtual bool
360   isVirtualOffsetNeededForVTableField(CodeGenFunction &CGF,
361                                       CodeGenFunction::VPtr Vptr) = 0;
362 
363   /// Checks if ABI requires to initilize vptrs for given dynamic class.
364   virtual bool doStructorsInitializeVPtrs(const CXXRecordDecl *VTableClass) = 0;
365 
366   /// Get the address point of the vtable for the given base subobject.
367   virtual llvm::Constant *
368   getVTableAddressPoint(BaseSubobject Base,
369                         const CXXRecordDecl *VTableClass) = 0;
370 
371   /// Get the address point of the vtable for the given base subobject while
372   /// building a constructor or a destructor.
373   virtual llvm::Value *
374   getVTableAddressPointInStructor(CodeGenFunction &CGF, const CXXRecordDecl *RD,
375                                   BaseSubobject Base,
376                                   const CXXRecordDecl *NearestVBase) = 0;
377 
378   /// Get the address point of the vtable for the given base subobject while
379   /// building a constexpr.
380   virtual llvm::Constant *
381   getVTableAddressPointForConstExpr(BaseSubobject Base,
382                                     const CXXRecordDecl *VTableClass) = 0;
383 
384   /// Get the address of the vtable for the given record decl which should be
385   /// used for the vptr at the given offset in RD.
386   virtual llvm::GlobalVariable *getAddrOfVTable(const CXXRecordDecl *RD,
387                                                 CharUnits VPtrOffset) = 0;
388 
389   /// Build a virtual function pointer in the ABI-specific way.
390   virtual llvm::Value *getVirtualFunctionPointer(CodeGenFunction &CGF,
391                                                  GlobalDecl GD,
392                                                  Address This,
393                                                  llvm::Type *Ty,
394                                                  SourceLocation Loc) = 0;
395 
396   /// Emit the ABI-specific virtual destructor call.
397   virtual llvm::Value *
398   EmitVirtualDestructorCall(CodeGenFunction &CGF, const CXXDestructorDecl *Dtor,
399                             CXXDtorType DtorType, Address This,
400                             const CXXMemberCallExpr *CE) = 0;
401 
adjustCallArgsForDestructorThunk(CodeGenFunction & CGF,GlobalDecl GD,CallArgList & CallArgs)402   virtual void adjustCallArgsForDestructorThunk(CodeGenFunction &CGF,
403                                                 GlobalDecl GD,
404                                                 CallArgList &CallArgs) {}
405 
406   /// Emit any tables needed to implement virtual inheritance.  For Itanium,
407   /// this emits virtual table tables.  For the MSVC++ ABI, this emits virtual
408   /// base tables.
409   virtual void emitVirtualInheritanceTables(const CXXRecordDecl *RD) = 0;
410 
411   virtual void setThunkLinkage(llvm::Function *Thunk, bool ForVTable,
412                                GlobalDecl GD, bool ReturnAdjustment) = 0;
413 
414   virtual llvm::Value *performThisAdjustment(CodeGenFunction &CGF,
415                                              Address This,
416                                              const ThisAdjustment &TA) = 0;
417 
418   virtual llvm::Value *performReturnAdjustment(CodeGenFunction &CGF,
419                                                Address Ret,
420                                                const ReturnAdjustment &RA) = 0;
421 
422   virtual void EmitReturnFromThunk(CodeGenFunction &CGF,
423                                    RValue RV, QualType ResultType);
424 
425   virtual size_t getSrcArgforCopyCtor(const CXXConstructorDecl *,
426                                       FunctionArgList &Args) const = 0;
427 
428   /// Gets the offsets of all the virtual base pointers in a given class.
429   virtual std::vector<CharUnits> getVBPtrOffsets(const CXXRecordDecl *RD);
430 
431   /// Gets the pure virtual member call function.
432   virtual StringRef GetPureVirtualCallName() = 0;
433 
434   /// Gets the deleted virtual member call name.
435   virtual StringRef GetDeletedVirtualCallName() = 0;
436 
437   /**************************** Array cookies ******************************/
438 
439   /// Returns the extra size required in order to store the array
440   /// cookie for the given new-expression.  May return 0 to indicate that no
441   /// array cookie is required.
442   ///
443   /// Several cases are filtered out before this method is called:
444   ///   - non-array allocations never need a cookie
445   ///   - calls to \::operator new(size_t, void*) never need a cookie
446   ///
447   /// \param expr - the new-expression being allocated.
448   virtual CharUnits GetArrayCookieSize(const CXXNewExpr *expr);
449 
450   /// Initialize the array cookie for the given allocation.
451   ///
452   /// \param NewPtr - a char* which is the presumed-non-null
453   ///   return value of the allocation function
454   /// \param NumElements - the computed number of elements,
455   ///   potentially collapsed from the multidimensional array case;
456   ///   always a size_t
457   /// \param ElementType - the base element allocated type,
458   ///   i.e. the allocated type after stripping all array types
459   virtual Address InitializeArrayCookie(CodeGenFunction &CGF,
460                                         Address NewPtr,
461                                         llvm::Value *NumElements,
462                                         const CXXNewExpr *expr,
463                                         QualType ElementType);
464 
465   /// Reads the array cookie associated with the given pointer,
466   /// if it has one.
467   ///
468   /// \param Ptr - a pointer to the first element in the array
469   /// \param ElementType - the base element type of elements of the array
470   /// \param NumElements - an out parameter which will be initialized
471   ///   with the number of elements allocated, or zero if there is no
472   ///   cookie
473   /// \param AllocPtr - an out parameter which will be initialized
474   ///   with a char* pointing to the address returned by the allocation
475   ///   function
476   /// \param CookieSize - an out parameter which will be initialized
477   ///   with the size of the cookie, or zero if there is no cookie
478   virtual void ReadArrayCookie(CodeGenFunction &CGF, Address Ptr,
479                                const CXXDeleteExpr *expr,
480                                QualType ElementType, llvm::Value *&NumElements,
481                                llvm::Value *&AllocPtr, CharUnits &CookieSize);
482 
483   /// Return whether the given global decl needs a VTT parameter.
484   virtual bool NeedsVTTParameter(GlobalDecl GD);
485 
486 protected:
487   /// Returns the extra size required in order to store the array
488   /// cookie for the given type.  Assumes that an array cookie is
489   /// required.
490   virtual CharUnits getArrayCookieSizeImpl(QualType elementType);
491 
492   /// Reads the array cookie for an allocation which is known to have one.
493   /// This is called by the standard implementation of ReadArrayCookie.
494   ///
495   /// \param ptr - a pointer to the allocation made for an array, as a char*
496   /// \param cookieSize - the computed cookie size of an array
497   ///
498   /// Other parameters are as above.
499   ///
500   /// \return a size_t
501   virtual llvm::Value *readArrayCookieImpl(CodeGenFunction &IGF, Address ptr,
502                                            CharUnits cookieSize);
503 
504 public:
505 
506   /*************************** Static local guards ****************************/
507 
508   /// Emits the guarded initializer and destructor setup for the given
509   /// variable, given that it couldn't be emitted as a constant.
510   /// If \p PerformInit is false, the initialization has been folded to a
511   /// constant and should not be performed.
512   ///
513   /// The variable may be:
514   ///   - a static local variable
515   ///   - a static data member of a class template instantiation
516   virtual void EmitGuardedInit(CodeGenFunction &CGF, const VarDecl &D,
517                                llvm::GlobalVariable *DeclPtr,
518                                bool PerformInit) = 0;
519 
520   /// Emit code to force the execution of a destructor during global
521   /// teardown.  The default implementation of this uses atexit.
522   ///
523   /// \param Dtor - a function taking a single pointer argument
524   /// \param Addr - a pointer to pass to the destructor function.
525   virtual void registerGlobalDtor(CodeGenFunction &CGF, const VarDecl &D,
526                                   llvm::Constant *Dtor,
527                                   llvm::Constant *Addr) = 0;
528 
529   /*************************** thread_local initialization ********************/
530 
531   /// Emits ABI-required functions necessary to initialize thread_local
532   /// variables in this translation unit.
533   ///
534   /// \param CXXThreadLocals - The thread_local declarations in this translation
535   ///        unit.
536   /// \param CXXThreadLocalInits - If this translation unit contains any
537   ///        non-constant initialization or non-trivial destruction for
538   ///        thread_local variables, a list of functions to perform the
539   ///        initialization.
540   virtual void EmitThreadLocalInitFuncs(
541       CodeGenModule &CGM, ArrayRef<const VarDecl *> CXXThreadLocals,
542       ArrayRef<llvm::Function *> CXXThreadLocalInits,
543       ArrayRef<const VarDecl *> CXXThreadLocalInitVars) = 0;
544 
545   // Determine if references to thread_local global variables can be made
546   // directly or require access through a thread wrapper function.
547   virtual bool usesThreadWrapperFunction() const = 0;
548 
549   /// Emit a reference to a non-local thread_local variable (including
550   /// triggering the initialization of all thread_local variables in its
551   /// translation unit).
552   virtual LValue EmitThreadLocalVarDeclLValue(CodeGenFunction &CGF,
553                                               const VarDecl *VD,
554                                               QualType LValType) = 0;
555 
556   /// Emit a single constructor/destructor with the given type from a C++
557   /// constructor Decl.
558   virtual void emitCXXStructor(const CXXMethodDecl *MD, StructorType Type) = 0;
559 };
560 
561 // Create an instance of a C++ ABI class:
562 
563 /// Creates an Itanium-family ABI.
564 CGCXXABI *CreateItaniumCXXABI(CodeGenModule &CGM);
565 
566 /// Creates a Microsoft-family ABI.
567 CGCXXABI *CreateMicrosoftCXXABI(CodeGenModule &CGM);
568 
569 }
570 }
571 
572 #endif
573