xref: /freebsd/contrib/llvm-project/clang/lib/CodeGen/CGCXXABI.h (revision 9f23cbd6cae82fd77edfad7173432fa8dccd0a95)
1 //===----- CGCXXABI.h - Interface to C++ ABIs -------------------*- C++ -*-===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 //
9 // This provides an abstract class for C++ code generation. Concrete subclasses
10 // of this implement code generation for specific C++ ABIs.
11 //
12 //===----------------------------------------------------------------------===//
13 
14 #ifndef LLVM_CLANG_LIB_CODEGEN_CGCXXABI_H
15 #define LLVM_CLANG_LIB_CODEGEN_CGCXXABI_H
16 
17 #include "CodeGenFunction.h"
18 #include "clang/Basic/LLVM.h"
19 #include "clang/CodeGen/CodeGenABITypes.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 MangleContext;
35 
36 namespace CodeGen {
37 class CGCallee;
38 class CodeGenFunction;
39 class CodeGenModule;
40 struct CatchTypeInfo;
41 
42 /// Implements C++ ABI-specific code generation functions.
43 class CGCXXABI {
44   friend class CodeGenModule;
45 
46 protected:
47   CodeGenModule &CGM;
48   std::unique_ptr<MangleContext> MangleCtx;
49 
50   CGCXXABI(CodeGenModule &CGM)
51     : CGM(CGM), MangleCtx(CGM.getContext().createMangleContext()) {}
52 
53 protected:
54   ImplicitParamDecl *getThisDecl(CodeGenFunction &CGF) {
55     return CGF.CXXABIThisDecl;
56   }
57   llvm::Value *getThisValue(CodeGenFunction &CGF) {
58     return CGF.CXXABIThisValue;
59   }
60   Address getThisAddress(CodeGenFunction &CGF) {
61     return Address(
62         CGF.CXXABIThisValue,
63         CGF.ConvertTypeForMem(CGF.CXXABIThisDecl->getType()->getPointeeType()),
64         CGF.CXXABIThisAlignment);
65   }
66 
67   /// Issue a diagnostic about unsupported features in the ABI.
68   void ErrorUnsupportedABI(CodeGenFunction &CGF, StringRef S);
69 
70   /// Get a null value for unsupported member pointers.
71   llvm::Constant *GetBogusMemberPointer(QualType T);
72 
73   ImplicitParamDecl *&getStructorImplicitParamDecl(CodeGenFunction &CGF) {
74     return CGF.CXXStructorImplicitParamDecl;
75   }
76   llvm::Value *&getStructorImplicitParamValue(CodeGenFunction &CGF) {
77     return CGF.CXXStructorImplicitParamValue;
78   }
79 
80   /// Loads the incoming C++ this pointer as it was passed by the caller.
81   llvm::Value *loadIncomingCXXThis(CodeGenFunction &CGF);
82 
83   void setCXXABIThisValue(CodeGenFunction &CGF, llvm::Value *ThisPtr);
84 
85   ASTContext &getContext() const { return CGM.getContext(); }
86 
87   bool mayNeedDestruction(const VarDecl *VD) const;
88 
89   /// Determine whether we will definitely emit this variable with a constant
90   /// initializer, either because the language semantics demand it or because
91   /// we know that the initializer is a constant.
92   // For weak definitions, any initializer available in the current translation
93   // is not necessarily reflective of the initializer used; such initializers
94   // are ignored unless if InspectInitForWeakDef is true.
95   bool
96   isEmittedWithConstantInitializer(const VarDecl *VD,
97                                    bool InspectInitForWeakDef = false) const;
98 
99   virtual bool requiresArrayCookie(const CXXDeleteExpr *E, QualType eltType);
100   virtual bool requiresArrayCookie(const CXXNewExpr *E);
101 
102   /// Determine whether there's something special about the rules of
103   /// the ABI tell us that 'this' is a complete object within the
104   /// given function.  Obvious common logic like being defined on a
105   /// final class will have been taken care of by the caller.
106   virtual bool isThisCompleteObject(GlobalDecl GD) const = 0;
107 
108   virtual bool constructorsAndDestructorsReturnThis() const {
109     return CGM.getCodeGenOpts().CtorDtorReturnThis;
110   }
111 
112 public:
113 
114   virtual ~CGCXXABI();
115 
116   /// Gets the mangle context.
117   MangleContext &getMangleContext() {
118     return *MangleCtx;
119   }
120 
121   /// Returns true if the given constructor or destructor is one of the
122   /// kinds that the ABI says returns 'this' (only applies when called
123   /// non-virtually for destructors).
124   ///
125   /// There currently is no way to indicate if a destructor returns 'this'
126   /// when called virtually, and code generation does not support the case.
127   virtual bool HasThisReturn(GlobalDecl GD) const {
128     if (isa<CXXConstructorDecl>(GD.getDecl()) ||
129         (isa<CXXDestructorDecl>(GD.getDecl()) &&
130          GD.getDtorType() != Dtor_Deleting))
131       return constructorsAndDestructorsReturnThis();
132     return false;
133   }
134 
135   virtual bool hasMostDerivedReturn(GlobalDecl GD) const { return false; }
136 
137   virtual bool useSinitAndSterm() const { return false; }
138 
139   /// Returns true if the target allows calling a function through a pointer
140   /// with a different signature than the actual function (or equivalently,
141   /// bitcasting a function or function pointer to a different function type).
142   /// In principle in the most general case this could depend on the target, the
143   /// calling convention, and the actual types of the arguments and return
144   /// value. Here it just means whether the signature mismatch could *ever* be
145   /// allowed; in other words, does the target do strict checking of signatures
146   /// for all calls.
147   virtual bool canCallMismatchedFunctionType() const { return true; }
148 
149   /// If the C++ ABI requires the given type be returned in a particular way,
150   /// this method sets RetAI and returns true.
151   virtual bool classifyReturnType(CGFunctionInfo &FI) const = 0;
152 
153   /// Specify how one should pass an argument of a record type.
154   enum RecordArgABI {
155     /// Pass it using the normal C aggregate rules for the ABI, potentially
156     /// introducing extra copies and passing some or all of it in registers.
157     RAA_Default = 0,
158 
159     /// Pass it on the stack using its defined layout.  The argument must be
160     /// evaluated directly into the correct stack position in the arguments area,
161     /// and the call machinery must not move it or introduce extra copies.
162     RAA_DirectInMemory,
163 
164     /// Pass it as a pointer to temporary memory.
165     RAA_Indirect
166   };
167 
168   /// Returns how an argument of the given record type should be passed.
169   virtual RecordArgABI getRecordArgABI(const CXXRecordDecl *RD) const = 0;
170 
171   /// Returns true if the implicit 'sret' parameter comes after the implicit
172   /// 'this' parameter of C++ instance methods.
173   virtual bool isSRetParameterAfterThis() const { return false; }
174 
175   /// Returns true if the ABI permits the argument to be a homogeneous
176   /// aggregate.
177   virtual bool
178   isPermittedToBeHomogeneousAggregate(const CXXRecordDecl *RD) const {
179     return true;
180   };
181 
182   /// Find the LLVM type used to represent the given member pointer
183   /// type.
184   virtual llvm::Type *
185   ConvertMemberPointerType(const MemberPointerType *MPT);
186 
187   /// Load a member function from an object and a member function
188   /// pointer.  Apply the this-adjustment and set 'This' to the
189   /// adjusted value.
190   virtual CGCallee EmitLoadOfMemberFunctionPointer(
191       CodeGenFunction &CGF, const Expr *E, Address This,
192       llvm::Value *&ThisPtrForCall, llvm::Value *MemPtr,
193       const MemberPointerType *MPT);
194 
195   /// Calculate an l-value from an object and a data member pointer.
196   virtual llvm::Value *
197   EmitMemberDataPointerAddress(CodeGenFunction &CGF, const Expr *E,
198                                Address Base, llvm::Value *MemPtr,
199                                const MemberPointerType *MPT);
200 
201   /// Perform a derived-to-base, base-to-derived, or bitcast member
202   /// pointer conversion.
203   virtual llvm::Value *EmitMemberPointerConversion(CodeGenFunction &CGF,
204                                                    const CastExpr *E,
205                                                    llvm::Value *Src);
206 
207   /// Perform a derived-to-base, base-to-derived, or bitcast member
208   /// pointer conversion on a constant value.
209   virtual llvm::Constant *EmitMemberPointerConversion(const CastExpr *E,
210                                                       llvm::Constant *Src);
211 
212   /// Return true if the given member pointer can be zero-initialized
213   /// (in the C++ sense) with an LLVM zeroinitializer.
214   virtual bool isZeroInitializable(const MemberPointerType *MPT);
215 
216   /// Return whether or not a member pointers type is convertible to an IR type.
217   virtual bool isMemberPointerConvertible(const MemberPointerType *MPT) const {
218     return true;
219   }
220 
221   /// Create a null member pointer of the given type.
222   virtual llvm::Constant *EmitNullMemberPointer(const MemberPointerType *MPT);
223 
224   /// Create a member pointer for the given method.
225   virtual llvm::Constant *EmitMemberFunctionPointer(const CXXMethodDecl *MD);
226 
227   /// Create a member pointer for the given field.
228   virtual llvm::Constant *EmitMemberDataPointer(const MemberPointerType *MPT,
229                                                 CharUnits offset);
230 
231   /// Create a member pointer for the given member pointer constant.
232   virtual llvm::Constant *EmitMemberPointer(const APValue &MP, QualType MPT);
233 
234   /// Emit a comparison between two member pointers.  Returns an i1.
235   virtual llvm::Value *
236   EmitMemberPointerComparison(CodeGenFunction &CGF,
237                               llvm::Value *L,
238                               llvm::Value *R,
239                               const MemberPointerType *MPT,
240                               bool Inequality);
241 
242   /// Determine if a member pointer is non-null.  Returns an i1.
243   virtual llvm::Value *
244   EmitMemberPointerIsNotNull(CodeGenFunction &CGF,
245                              llvm::Value *MemPtr,
246                              const MemberPointerType *MPT);
247 
248 protected:
249   /// A utility method for computing the offset required for the given
250   /// base-to-derived or derived-to-base member-pointer conversion.
251   /// Does not handle virtual conversions (in case we ever fully
252   /// support an ABI that allows this).  Returns null if no adjustment
253   /// is required.
254   llvm::Constant *getMemberPointerAdjustment(const CastExpr *E);
255 
256 public:
257   virtual void emitVirtualObjectDelete(CodeGenFunction &CGF,
258                                        const CXXDeleteExpr *DE,
259                                        Address Ptr, QualType ElementType,
260                                        const CXXDestructorDecl *Dtor) = 0;
261   virtual void emitRethrow(CodeGenFunction &CGF, bool isNoReturn) = 0;
262   virtual void emitThrow(CodeGenFunction &CGF, const CXXThrowExpr *E) = 0;
263   virtual llvm::GlobalVariable *getThrowInfo(QualType T) { return nullptr; }
264 
265   /// Determine whether it's possible to emit a vtable for \p RD, even
266   /// though we do not know that the vtable has been marked as used by semantic
267   /// analysis.
268   virtual bool canSpeculativelyEmitVTable(const CXXRecordDecl *RD) const = 0;
269 
270   virtual void emitBeginCatch(CodeGenFunction &CGF, const CXXCatchStmt *C) = 0;
271 
272   virtual llvm::CallInst *
273   emitTerminateForUnexpectedException(CodeGenFunction &CGF,
274                                       llvm::Value *Exn);
275 
276   virtual llvm::Constant *getAddrOfRTTIDescriptor(QualType Ty) = 0;
277   virtual CatchTypeInfo
278   getAddrOfCXXCatchHandlerType(QualType Ty, QualType CatchHandlerType) = 0;
279   virtual CatchTypeInfo getCatchAllTypeInfo();
280 
281   virtual bool shouldTypeidBeNullChecked(bool IsDeref,
282                                          QualType SrcRecordTy) = 0;
283   virtual void EmitBadTypeidCall(CodeGenFunction &CGF) = 0;
284   virtual llvm::Value *EmitTypeid(CodeGenFunction &CGF, QualType SrcRecordTy,
285                                   Address ThisPtr,
286                                   llvm::Type *StdTypeInfoPtrTy) = 0;
287 
288   virtual bool shouldDynamicCastCallBeNullChecked(bool SrcIsPtr,
289                                                   QualType SrcRecordTy) = 0;
290 
291   virtual llvm::Value *
292   EmitDynamicCastCall(CodeGenFunction &CGF, Address Value,
293                       QualType SrcRecordTy, QualType DestTy,
294                       QualType DestRecordTy, llvm::BasicBlock *CastEnd) = 0;
295 
296   virtual llvm::Value *EmitDynamicCastToVoid(CodeGenFunction &CGF,
297                                              Address Value,
298                                              QualType SrcRecordTy,
299                                              QualType DestTy) = 0;
300 
301   virtual bool EmitBadCastCall(CodeGenFunction &CGF) = 0;
302 
303   virtual llvm::Value *GetVirtualBaseClassOffset(CodeGenFunction &CGF,
304                                                  Address This,
305                                                  const CXXRecordDecl *ClassDecl,
306                                         const CXXRecordDecl *BaseClassDecl) = 0;
307 
308   virtual llvm::BasicBlock *EmitCtorCompleteObjectHandler(CodeGenFunction &CGF,
309                                                           const CXXRecordDecl *RD);
310 
311   /// Emit the code to initialize hidden members required
312   /// to handle virtual inheritance, if needed by the ABI.
313   virtual void
314   initializeHiddenVirtualInheritanceMembers(CodeGenFunction &CGF,
315                                             const CXXRecordDecl *RD) {}
316 
317   /// Emit constructor variants required by this ABI.
318   virtual void EmitCXXConstructors(const CXXConstructorDecl *D) = 0;
319 
320   /// Additional implicit arguments to add to the beginning (Prefix) and end
321   /// (Suffix) of a constructor / destructor arg list.
322   ///
323   /// Note that Prefix should actually be inserted *after* the first existing
324   /// arg; `this` arguments always come first.
325   struct AddedStructorArgs {
326     struct Arg {
327       llvm::Value *Value;
328       QualType Type;
329     };
330     SmallVector<Arg, 1> Prefix;
331     SmallVector<Arg, 1> Suffix;
332     AddedStructorArgs() = default;
333     AddedStructorArgs(SmallVector<Arg, 1> P, SmallVector<Arg, 1> S)
334         : Prefix(std::move(P)), Suffix(std::move(S)) {}
335     static AddedStructorArgs prefix(SmallVector<Arg, 1> Args) {
336       return {std::move(Args), {}};
337     }
338     static AddedStructorArgs suffix(SmallVector<Arg, 1> Args) {
339       return {{}, std::move(Args)};
340     }
341   };
342 
343   /// Similar to AddedStructorArgs, but only notes the number of additional
344   /// arguments.
345   struct AddedStructorArgCounts {
346     unsigned Prefix = 0;
347     unsigned Suffix = 0;
348     AddedStructorArgCounts() = default;
349     AddedStructorArgCounts(unsigned P, unsigned S) : Prefix(P), Suffix(S) {}
350     static AddedStructorArgCounts prefix(unsigned N) { return {N, 0}; }
351     static AddedStructorArgCounts suffix(unsigned N) { return {0, N}; }
352   };
353 
354   /// Build the signature of the given constructor or destructor variant by
355   /// adding any required parameters.  For convenience, ArgTys has been
356   /// initialized with the type of 'this'.
357   virtual AddedStructorArgCounts
358   buildStructorSignature(GlobalDecl GD,
359                          SmallVectorImpl<CanQualType> &ArgTys) = 0;
360 
361   /// Returns true if the given destructor type should be emitted as a linkonce
362   /// delegating thunk, regardless of whether the dtor is defined in this TU or
363   /// not.
364   virtual bool useThunkForDtorVariant(const CXXDestructorDecl *Dtor,
365                                       CXXDtorType DT) const = 0;
366 
367   virtual void setCXXDestructorDLLStorage(llvm::GlobalValue *GV,
368                                           const CXXDestructorDecl *Dtor,
369                                           CXXDtorType DT) const;
370 
371   virtual llvm::GlobalValue::LinkageTypes
372   getCXXDestructorLinkage(GVALinkage Linkage, const CXXDestructorDecl *Dtor,
373                           CXXDtorType DT) const;
374 
375   /// Emit destructor variants required by this ABI.
376   virtual void EmitCXXDestructors(const CXXDestructorDecl *D) = 0;
377 
378   /// Get the type of the implicit "this" parameter used by a method. May return
379   /// zero if no specific type is applicable, e.g. if the ABI expects the "this"
380   /// parameter to point to some artificial offset in a complete object due to
381   /// vbases being reordered.
382   virtual const CXXRecordDecl *getThisArgumentTypeForMethod(GlobalDecl GD) {
383     return cast<CXXMethodDecl>(GD.getDecl())->getParent();
384   }
385 
386   /// Perform ABI-specific "this" argument adjustment required prior to
387   /// a call of a virtual function.
388   /// The "VirtualCall" argument is true iff the call itself is virtual.
389   virtual Address
390   adjustThisArgumentForVirtualFunctionCall(CodeGenFunction &CGF, GlobalDecl GD,
391                                            Address This, bool VirtualCall) {
392     return This;
393   }
394 
395   /// Build a parameter variable suitable for 'this'.
396   void buildThisParam(CodeGenFunction &CGF, FunctionArgList &Params);
397 
398   /// Insert any ABI-specific implicit parameters into the parameter list for a
399   /// function.  This generally involves extra data for constructors and
400   /// destructors.
401   ///
402   /// ABIs may also choose to override the return type, which has been
403   /// initialized with the type of 'this' if HasThisReturn(CGF.CurGD) is true or
404   /// the formal return type of the function otherwise.
405   virtual void addImplicitStructorParams(CodeGenFunction &CGF, QualType &ResTy,
406                                          FunctionArgList &Params) = 0;
407 
408   /// Get the ABI-specific "this" parameter adjustment to apply in the prologue
409   /// of a virtual function.
410   virtual CharUnits getVirtualFunctionPrologueThisAdjustment(GlobalDecl GD) {
411     return CharUnits::Zero();
412   }
413 
414   /// Emit the ABI-specific prolog for the function.
415   virtual void EmitInstanceFunctionProlog(CodeGenFunction &CGF) = 0;
416 
417   virtual AddedStructorArgs
418   getImplicitConstructorArgs(CodeGenFunction &CGF, const CXXConstructorDecl *D,
419                              CXXCtorType Type, bool ForVirtualBase,
420                              bool Delegating) = 0;
421 
422   /// Add any ABI-specific implicit arguments needed to call a constructor.
423   ///
424   /// \return The number of arguments added at the beginning and end of the
425   /// call, which is typically zero or one.
426   AddedStructorArgCounts
427   addImplicitConstructorArgs(CodeGenFunction &CGF, const CXXConstructorDecl *D,
428                              CXXCtorType Type, bool ForVirtualBase,
429                              bool Delegating, CallArgList &Args);
430 
431   /// Get the implicit (second) parameter that comes after the "this" pointer,
432   /// or nullptr if there is isn't one.
433   virtual llvm::Value *
434   getCXXDestructorImplicitParam(CodeGenFunction &CGF,
435                                 const CXXDestructorDecl *DD, CXXDtorType Type,
436                                 bool ForVirtualBase, bool Delegating) = 0;
437 
438   /// Emit the destructor call.
439   virtual void EmitDestructorCall(CodeGenFunction &CGF,
440                                   const CXXDestructorDecl *DD, CXXDtorType Type,
441                                   bool ForVirtualBase, bool Delegating,
442                                   Address This, QualType ThisTy) = 0;
443 
444   /// Emits the VTable definitions required for the given record type.
445   virtual void emitVTableDefinitions(CodeGenVTables &CGVT,
446                                      const CXXRecordDecl *RD) = 0;
447 
448   /// Checks if ABI requires extra virtual offset for vtable field.
449   virtual bool
450   isVirtualOffsetNeededForVTableField(CodeGenFunction &CGF,
451                                       CodeGenFunction::VPtr Vptr) = 0;
452 
453   /// Checks if ABI requires to initialize vptrs for given dynamic class.
454   virtual bool doStructorsInitializeVPtrs(const CXXRecordDecl *VTableClass) = 0;
455 
456   /// Get the address point of the vtable for the given base subobject.
457   virtual llvm::Constant *
458   getVTableAddressPoint(BaseSubobject Base,
459                         const CXXRecordDecl *VTableClass) = 0;
460 
461   /// Get the address point of the vtable for the given base subobject while
462   /// building a constructor or a destructor.
463   virtual llvm::Value *
464   getVTableAddressPointInStructor(CodeGenFunction &CGF, const CXXRecordDecl *RD,
465                                   BaseSubobject Base,
466                                   const CXXRecordDecl *NearestVBase) = 0;
467 
468   /// Get the address point of the vtable for the given base subobject while
469   /// building a constexpr.
470   virtual llvm::Constant *
471   getVTableAddressPointForConstExpr(BaseSubobject Base,
472                                     const CXXRecordDecl *VTableClass) = 0;
473 
474   /// Get the address of the vtable for the given record decl which should be
475   /// used for the vptr at the given offset in RD.
476   virtual llvm::GlobalVariable *getAddrOfVTable(const CXXRecordDecl *RD,
477                                                 CharUnits VPtrOffset) = 0;
478 
479   /// Build a virtual function pointer in the ABI-specific way.
480   virtual CGCallee getVirtualFunctionPointer(CodeGenFunction &CGF,
481                                              GlobalDecl GD, Address This,
482                                              llvm::Type *Ty,
483                                              SourceLocation Loc) = 0;
484 
485   using DeleteOrMemberCallExpr =
486       llvm::PointerUnion<const CXXDeleteExpr *, const CXXMemberCallExpr *>;
487 
488   /// Emit the ABI-specific virtual destructor call.
489   virtual llvm::Value *EmitVirtualDestructorCall(CodeGenFunction &CGF,
490                                                  const CXXDestructorDecl *Dtor,
491                                                  CXXDtorType DtorType,
492                                                  Address This,
493                                                  DeleteOrMemberCallExpr E) = 0;
494 
495   virtual void adjustCallArgsForDestructorThunk(CodeGenFunction &CGF,
496                                                 GlobalDecl GD,
497                                                 CallArgList &CallArgs) {}
498 
499   /// Emit any tables needed to implement virtual inheritance.  For Itanium,
500   /// this emits virtual table tables.  For the MSVC++ ABI, this emits virtual
501   /// base tables.
502   virtual void emitVirtualInheritanceTables(const CXXRecordDecl *RD) = 0;
503 
504   virtual bool exportThunk() = 0;
505   virtual void setThunkLinkage(llvm::Function *Thunk, bool ForVTable,
506                                GlobalDecl GD, bool ReturnAdjustment) = 0;
507 
508   virtual llvm::Value *performThisAdjustment(CodeGenFunction &CGF,
509                                              Address This,
510                                              const ThisAdjustment &TA) = 0;
511 
512   virtual llvm::Value *performReturnAdjustment(CodeGenFunction &CGF,
513                                                Address Ret,
514                                                const ReturnAdjustment &RA) = 0;
515 
516   virtual void EmitReturnFromThunk(CodeGenFunction &CGF,
517                                    RValue RV, QualType ResultType);
518 
519   virtual size_t getSrcArgforCopyCtor(const CXXConstructorDecl *,
520                                       FunctionArgList &Args) const = 0;
521 
522   /// Gets the offsets of all the virtual base pointers in a given class.
523   virtual std::vector<CharUnits> getVBPtrOffsets(const CXXRecordDecl *RD);
524 
525   /// Gets the pure virtual member call function.
526   virtual StringRef GetPureVirtualCallName() = 0;
527 
528   /// Gets the deleted virtual member call name.
529   virtual StringRef GetDeletedVirtualCallName() = 0;
530 
531   /**************************** Array cookies ******************************/
532 
533   /// Returns the extra size required in order to store the array
534   /// cookie for the given new-expression.  May return 0 to indicate that no
535   /// array cookie is required.
536   ///
537   /// Several cases are filtered out before this method is called:
538   ///   - non-array allocations never need a cookie
539   ///   - calls to \::operator new(size_t, void*) never need a cookie
540   ///
541   /// \param expr - the new-expression being allocated.
542   virtual CharUnits GetArrayCookieSize(const CXXNewExpr *expr);
543 
544   /// Initialize the array cookie for the given allocation.
545   ///
546   /// \param NewPtr - a char* which is the presumed-non-null
547   ///   return value of the allocation function
548   /// \param NumElements - the computed number of elements,
549   ///   potentially collapsed from the multidimensional array case;
550   ///   always a size_t
551   /// \param ElementType - the base element allocated type,
552   ///   i.e. the allocated type after stripping all array types
553   virtual Address InitializeArrayCookie(CodeGenFunction &CGF,
554                                         Address NewPtr,
555                                         llvm::Value *NumElements,
556                                         const CXXNewExpr *expr,
557                                         QualType ElementType);
558 
559   /// Reads the array cookie associated with the given pointer,
560   /// if it has one.
561   ///
562   /// \param Ptr - a pointer to the first element in the array
563   /// \param ElementType - the base element type of elements of the array
564   /// \param NumElements - an out parameter which will be initialized
565   ///   with the number of elements allocated, or zero if there is no
566   ///   cookie
567   /// \param AllocPtr - an out parameter which will be initialized
568   ///   with a char* pointing to the address returned by the allocation
569   ///   function
570   /// \param CookieSize - an out parameter which will be initialized
571   ///   with the size of the cookie, or zero if there is no cookie
572   virtual void ReadArrayCookie(CodeGenFunction &CGF, Address Ptr,
573                                const CXXDeleteExpr *expr,
574                                QualType ElementType, llvm::Value *&NumElements,
575                                llvm::Value *&AllocPtr, CharUnits &CookieSize);
576 
577   /// Return whether the given global decl needs a VTT parameter.
578   virtual bool NeedsVTTParameter(GlobalDecl GD);
579 
580 protected:
581   /// Returns the extra size required in order to store the array
582   /// cookie for the given type.  Assumes that an array cookie is
583   /// required.
584   virtual CharUnits getArrayCookieSizeImpl(QualType elementType);
585 
586   /// Reads the array cookie for an allocation which is known to have one.
587   /// This is called by the standard implementation of ReadArrayCookie.
588   ///
589   /// \param ptr - a pointer to the allocation made for an array, as a char*
590   /// \param cookieSize - the computed cookie size of an array
591   ///
592   /// Other parameters are as above.
593   ///
594   /// \return a size_t
595   virtual llvm::Value *readArrayCookieImpl(CodeGenFunction &IGF, Address ptr,
596                                            CharUnits cookieSize);
597 
598 public:
599 
600   /*************************** Static local guards ****************************/
601 
602   /// Emits the guarded initializer and destructor setup for the given
603   /// variable, given that it couldn't be emitted as a constant.
604   /// If \p PerformInit is false, the initialization has been folded to a
605   /// constant and should not be performed.
606   ///
607   /// The variable may be:
608   ///   - a static local variable
609   ///   - a static data member of a class template instantiation
610   virtual void EmitGuardedInit(CodeGenFunction &CGF, const VarDecl &D,
611                                llvm::GlobalVariable *DeclPtr,
612                                bool PerformInit) = 0;
613 
614   /// Emit code to force the execution of a destructor during global
615   /// teardown.  The default implementation of this uses atexit.
616   ///
617   /// \param Dtor - a function taking a single pointer argument
618   /// \param Addr - a pointer to pass to the destructor function.
619   virtual void registerGlobalDtor(CodeGenFunction &CGF, const VarDecl &D,
620                                   llvm::FunctionCallee Dtor,
621                                   llvm::Constant *Addr) = 0;
622 
623   /*************************** thread_local initialization ********************/
624 
625   /// Emits ABI-required functions necessary to initialize thread_local
626   /// variables in this translation unit.
627   ///
628   /// \param CXXThreadLocals - The thread_local declarations in this translation
629   ///        unit.
630   /// \param CXXThreadLocalInits - If this translation unit contains any
631   ///        non-constant initialization or non-trivial destruction for
632   ///        thread_local variables, a list of functions to perform the
633   ///        initialization.
634   virtual void EmitThreadLocalInitFuncs(
635       CodeGenModule &CGM, ArrayRef<const VarDecl *> CXXThreadLocals,
636       ArrayRef<llvm::Function *> CXXThreadLocalInits,
637       ArrayRef<const VarDecl *> CXXThreadLocalInitVars) = 0;
638 
639   // Determine if references to thread_local global variables can be made
640   // directly or require access through a thread wrapper function.
641   virtual bool usesThreadWrapperFunction(const VarDecl *VD) const = 0;
642 
643   /// Emit a reference to a non-local thread_local variable (including
644   /// triggering the initialization of all thread_local variables in its
645   /// translation unit).
646   virtual LValue EmitThreadLocalVarDeclLValue(CodeGenFunction &CGF,
647                                               const VarDecl *VD,
648                                               QualType LValType) = 0;
649 
650   /// Emit a single constructor/destructor with the given type from a C++
651   /// constructor Decl.
652   virtual void emitCXXStructor(GlobalDecl GD) = 0;
653 
654   /// Load a vtable from This, an object of polymorphic type RD, or from one of
655   /// its virtual bases if it does not have its own vtable. Returns the vtable
656   /// and the class from which the vtable was loaded.
657   virtual std::pair<llvm::Value *, const CXXRecordDecl *>
658   LoadVTablePtr(CodeGenFunction &CGF, Address This,
659                 const CXXRecordDecl *RD) = 0;
660 };
661 
662 // Create an instance of a C++ ABI class:
663 
664 /// Creates an Itanium-family ABI.
665 CGCXXABI *CreateItaniumCXXABI(CodeGenModule &CGM);
666 
667 /// Creates a Microsoft-family ABI.
668 CGCXXABI *CreateMicrosoftCXXABI(CodeGenModule &CGM);
669 
670 struct CatchRetScope final : EHScopeStack::Cleanup {
671   llvm::CatchPadInst *CPI;
672 
673   CatchRetScope(llvm::CatchPadInst *CPI) : CPI(CPI) {}
674 
675   void Emit(CodeGenFunction &CGF, Flags flags) override {
676     llvm::BasicBlock *BB = CGF.createBasicBlock("catchret.dest");
677     CGF.Builder.CreateCatchRet(CPI, BB);
678     CGF.EmitBlock(BB);
679   }
680 };
681 }
682 }
683 
684 #endif
685