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
21namespace llvm {
22class Constant;
23class Type;
24class Value;
25class CallInst;
26}
27
28namespace clang {
29class CastExpr;
30class CXXConstructorDecl;
31class CXXDestructorDecl;
32class CXXMethodDecl;
33class CXXRecordDecl;
34class MangleContext;
35
36namespace CodeGen {
37class CGCallee;
38class CodeGenFunction;
39class CodeGenModule;
40struct CatchTypeInfo;
41
42/// Implements C++ ABI-specific code generation functions.
43class CGCXXABI {
44  friend class CodeGenModule;
45
46protected:
47  CodeGenModule &CGM;
48  std::unique_ptr<MangleContext> MangleCtx;
49
50  CGCXXABI(CodeGenModule &CGM)
51    : CGM(CGM), MangleCtx(CGM.getContext().createMangleContext()) {}
52
53protected:
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
112public:
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
248protected:
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
256public:
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
580protected:
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
598public:
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.
665CGCXXABI *CreateItaniumCXXABI(CodeGenModule &CGM);
666
667/// Creates a Microsoft-family ABI.
668CGCXXABI *CreateMicrosoftCXXABI(CodeGenModule &CGM);
669
670struct 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