1 //===----- CGCXXABI.h - Interface to C++ ABIs -------------------*- C++ -*-===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This provides an abstract class for C++ code generation. Concrete subclasses
11 // of this implement code generation for specific C++ ABIs.
13 //===----------------------------------------------------------------------===//
15 #ifndef LLVM_CLANG_LIB_CODEGEN_CGCXXABI_H
16 #define LLVM_CLANG_LIB_CODEGEN_CGCXXABI_H
18 #include "CodeGenFunction.h"
19 #include "clang/Basic/LLVM.h"
30 class CXXConstructorDecl;
31 class CXXDestructorDecl;
38 class CodeGenFunction;
41 /// \brief Implements C++ ABI-specific code generation functions.
45 std::unique_ptr<MangleContext> MangleCtx;
47 CGCXXABI(CodeGenModule &CGM)
48 : CGM(CGM), MangleCtx(CGM.getContext().createMangleContext()) {}
51 ImplicitParamDecl *&getThisDecl(CodeGenFunction &CGF) {
52 return CGF.CXXABIThisDecl;
54 llvm::Value *&getThisValue(CodeGenFunction &CGF) {
55 return CGF.CXXABIThisValue;
58 /// Issue a diagnostic about unsupported features in the ABI.
59 void ErrorUnsupportedABI(CodeGenFunction &CGF, StringRef S);
61 /// Get a null value for unsupported member pointers.
62 llvm::Constant *GetBogusMemberPointer(QualType T);
64 ImplicitParamDecl *&getStructorImplicitParamDecl(CodeGenFunction &CGF) {
65 return CGF.CXXStructorImplicitParamDecl;
67 llvm::Value *&getStructorImplicitParamValue(CodeGenFunction &CGF) {
68 return CGF.CXXStructorImplicitParamValue;
71 /// Perform prolog initialization of the parameter variable suitable
72 /// for 'this' emitted by buildThisParam.
73 void EmitThisParam(CodeGenFunction &CGF);
75 ASTContext &getContext() const { return CGM.getContext(); }
77 virtual bool requiresArrayCookie(const CXXDeleteExpr *E, QualType eltType);
78 virtual bool requiresArrayCookie(const CXXNewExpr *E);
84 /// Gets the mangle context.
85 MangleContext &getMangleContext() {
89 /// Returns true if the given constructor or destructor is one of the
90 /// kinds that the ABI says returns 'this' (only applies when called
91 /// non-virtually for destructors).
93 /// There currently is no way to indicate if a destructor returns 'this'
94 /// when called virtually, and code generation does not support the case.
95 virtual bool HasThisReturn(GlobalDecl GD) const { return false; }
97 virtual bool hasMostDerivedReturn(GlobalDecl GD) const { return false; }
99 /// If the C++ ABI requires the given type be returned in a particular way,
100 /// this method sets RetAI and returns true.
101 virtual bool classifyReturnType(CGFunctionInfo &FI) const = 0;
103 /// Specify how one should pass an argument of a record type.
105 /// Pass it using the normal C aggregate rules for the ABI, potentially
106 /// introducing extra copies and passing some or all of it in registers.
109 /// Pass it on the stack using its defined layout. The argument must be
110 /// evaluated directly into the correct stack position in the arguments area,
111 /// and the call machinery must not move it or introduce extra copies.
114 /// Pass it as a pointer to temporary memory.
118 /// Returns true if C++ allows us to copy the memory of an object of type RD
119 /// when it is passed as an argument.
120 bool canCopyArgument(const CXXRecordDecl *RD) const;
122 /// Returns how an argument of the given record type should be passed.
123 virtual RecordArgABI getRecordArgABI(const CXXRecordDecl *RD) const = 0;
125 /// Returns true if the implicit 'sret' parameter comes after the implicit
126 /// 'this' parameter of C++ instance methods.
127 virtual bool isSRetParameterAfterThis() const { return false; }
129 /// Find the LLVM type used to represent the given member pointer
132 ConvertMemberPointerType(const MemberPointerType *MPT);
134 /// Load a member function from an object and a member function
135 /// pointer. Apply the this-adjustment and set 'This' to the
137 virtual llvm::Value *EmitLoadOfMemberFunctionPointer(
138 CodeGenFunction &CGF, const Expr *E, llvm::Value *&This,
139 llvm::Value *MemPtr, const MemberPointerType *MPT);
141 /// Calculate an l-value from an object and a data member pointer.
142 virtual llvm::Value *
143 EmitMemberDataPointerAddress(CodeGenFunction &CGF, const Expr *E,
144 llvm::Value *Base, llvm::Value *MemPtr,
145 const MemberPointerType *MPT);
147 /// Perform a derived-to-base, base-to-derived, or bitcast member
148 /// pointer conversion.
149 virtual llvm::Value *EmitMemberPointerConversion(CodeGenFunction &CGF,
153 /// Perform a derived-to-base, base-to-derived, or bitcast member
154 /// pointer conversion on a constant value.
155 virtual llvm::Constant *EmitMemberPointerConversion(const CastExpr *E,
156 llvm::Constant *Src);
158 /// Return true if the given member pointer can be zero-initialized
159 /// (in the C++ sense) with an LLVM zeroinitializer.
160 virtual bool isZeroInitializable(const MemberPointerType *MPT);
162 /// Return whether or not a member pointers type is convertible to an IR type.
163 virtual bool isMemberPointerConvertible(const MemberPointerType *MPT) const {
167 virtual bool isTypeInfoCalculable(QualType Ty) const {
168 return !Ty->isIncompleteType();
171 /// Create a null member pointer of the given type.
172 virtual llvm::Constant *EmitNullMemberPointer(const MemberPointerType *MPT);
174 /// Create a member pointer for the given method.
175 virtual llvm::Constant *EmitMemberPointer(const CXXMethodDecl *MD);
177 /// Create a member pointer for the given field.
178 virtual llvm::Constant *EmitMemberDataPointer(const MemberPointerType *MPT,
181 /// Create a member pointer for the given member pointer constant.
182 virtual llvm::Constant *EmitMemberPointer(const APValue &MP, QualType MPT);
184 /// Emit a comparison between two member pointers. Returns an i1.
185 virtual llvm::Value *
186 EmitMemberPointerComparison(CodeGenFunction &CGF,
189 const MemberPointerType *MPT,
192 /// Determine if a member pointer is non-null. Returns an i1.
193 virtual llvm::Value *
194 EmitMemberPointerIsNotNull(CodeGenFunction &CGF,
196 const MemberPointerType *MPT);
199 /// A utility method for computing the offset required for the given
200 /// base-to-derived or derived-to-base member-pointer conversion.
201 /// Does not handle virtual conversions (in case we ever fully
202 /// support an ABI that allows this). Returns null if no adjustment
204 llvm::Constant *getMemberPointerAdjustment(const CastExpr *E);
206 /// \brief Computes the non-virtual adjustment needed for a member pointer
207 /// conversion along an inheritance path stored in an APValue. Unlike
208 /// getMemberPointerAdjustment(), the adjustment can be negative if the path
209 /// is from a derived type to a base type.
210 CharUnits getMemberPointerPathAdjustment(const APValue &MP);
213 virtual void emitVirtualObjectDelete(CodeGenFunction &CGF,
214 const CXXDeleteExpr *DE,
215 llvm::Value *Ptr, QualType ElementType,
216 const CXXDestructorDecl *Dtor) = 0;
217 virtual void emitRethrow(CodeGenFunction &CGF, bool isNoReturn) = 0;
218 virtual void emitThrow(CodeGenFunction &CGF, const CXXThrowExpr *E) = 0;
219 virtual llvm::GlobalVariable *getThrowInfo(QualType T) { return nullptr; }
221 virtual void emitBeginCatch(CodeGenFunction &CGF, const CXXCatchStmt *C) = 0;
223 virtual llvm::CallInst *
224 emitTerminateForUnexpectedException(CodeGenFunction &CGF,
227 virtual llvm::Constant *getAddrOfRTTIDescriptor(QualType Ty) = 0;
228 virtual llvm::Constant *
229 getAddrOfCXXCatchHandlerType(QualType Ty, QualType CatchHandlerType) = 0;
231 virtual bool shouldTypeidBeNullChecked(bool IsDeref,
232 QualType SrcRecordTy) = 0;
233 virtual void EmitBadTypeidCall(CodeGenFunction &CGF) = 0;
234 virtual llvm::Value *EmitTypeid(CodeGenFunction &CGF, QualType SrcRecordTy,
235 llvm::Value *ThisPtr,
236 llvm::Type *StdTypeInfoPtrTy) = 0;
238 virtual bool shouldDynamicCastCallBeNullChecked(bool SrcIsPtr,
239 QualType SrcRecordTy) = 0;
241 virtual llvm::Value *
242 EmitDynamicCastCall(CodeGenFunction &CGF, llvm::Value *Value,
243 QualType SrcRecordTy, QualType DestTy,
244 QualType DestRecordTy, llvm::BasicBlock *CastEnd) = 0;
246 virtual llvm::Value *EmitDynamicCastToVoid(CodeGenFunction &CGF,
248 QualType SrcRecordTy,
249 QualType DestTy) = 0;
251 virtual bool EmitBadCastCall(CodeGenFunction &CGF) = 0;
253 virtual llvm::Value *GetVirtualBaseClassOffset(CodeGenFunction &CGF,
255 const CXXRecordDecl *ClassDecl,
256 const CXXRecordDecl *BaseClassDecl) = 0;
258 virtual llvm::BasicBlock *EmitCtorCompleteObjectHandler(CodeGenFunction &CGF,
259 const CXXRecordDecl *RD);
261 /// Emit the code to initialize hidden members required
262 /// to handle virtual inheritance, if needed by the ABI.
264 initializeHiddenVirtualInheritanceMembers(CodeGenFunction &CGF,
265 const CXXRecordDecl *RD) {}
267 /// Emit constructor variants required by this ABI.
268 virtual void EmitCXXConstructors(const CXXConstructorDecl *D) = 0;
270 /// Build the signature of the given constructor or destructor variant by
271 /// adding any required parameters. For convenience, ArgTys has been
272 /// initialized with the type of 'this'.
273 virtual void buildStructorSignature(const CXXMethodDecl *MD, StructorType T,
274 SmallVectorImpl<CanQualType> &ArgTys) = 0;
276 /// Returns true if the given destructor type should be emitted as a linkonce
277 /// delegating thunk, regardless of whether the dtor is defined in this TU or
279 virtual bool useThunkForDtorVariant(const CXXDestructorDecl *Dtor,
280 CXXDtorType DT) const = 0;
282 /// Emit destructor variants required by this ABI.
283 virtual void EmitCXXDestructors(const CXXDestructorDecl *D) = 0;
285 /// Get the type of the implicit "this" parameter used by a method. May return
286 /// zero if no specific type is applicable, e.g. if the ABI expects the "this"
287 /// parameter to point to some artificial offset in a complete object due to
288 /// vbases being reordered.
289 virtual const CXXRecordDecl *
290 getThisArgumentTypeForMethod(const CXXMethodDecl *MD) {
291 return MD->getParent();
294 /// Perform ABI-specific "this" argument adjustment required prior to
295 /// a call of a virtual function.
296 /// The "VirtualCall" argument is true iff the call itself is virtual.
297 virtual llvm::Value *
298 adjustThisArgumentForVirtualFunctionCall(CodeGenFunction &CGF, GlobalDecl GD,
304 /// Build a parameter variable suitable for 'this'.
305 void buildThisParam(CodeGenFunction &CGF, FunctionArgList &Params);
307 /// Insert any ABI-specific implicit parameters into the parameter list for a
308 /// function. This generally involves extra data for constructors and
311 /// ABIs may also choose to override the return type, which has been
312 /// initialized with the type of 'this' if HasThisReturn(CGF.CurGD) is true or
313 /// the formal return type of the function otherwise.
314 virtual void addImplicitStructorParams(CodeGenFunction &CGF, QualType &ResTy,
315 FunctionArgList &Params) = 0;
317 /// Perform ABI-specific "this" parameter adjustment in a virtual function
319 virtual llvm::Value *adjustThisParameterInVirtualFunctionPrologue(
320 CodeGenFunction &CGF, GlobalDecl GD, llvm::Value *This) {
324 /// Emit the ABI-specific prolog for the function.
325 virtual void EmitInstanceFunctionProlog(CodeGenFunction &CGF) = 0;
327 /// Add any ABI-specific implicit arguments needed to call a constructor.
329 /// \return The number of args added to the call, which is typically zero or
332 addImplicitConstructorArgs(CodeGenFunction &CGF, const CXXConstructorDecl *D,
333 CXXCtorType Type, bool ForVirtualBase,
334 bool Delegating, CallArgList &Args) = 0;
336 /// Emit the destructor call.
337 virtual void EmitDestructorCall(CodeGenFunction &CGF,
338 const CXXDestructorDecl *DD, CXXDtorType Type,
339 bool ForVirtualBase, bool Delegating,
340 llvm::Value *This) = 0;
342 /// Emits the VTable definitions required for the given record type.
343 virtual void emitVTableDefinitions(CodeGenVTables &CGVT,
344 const CXXRecordDecl *RD) = 0;
346 /// Get the address point of the vtable for the given base subobject while
347 /// building a constructor or a destructor. On return, NeedsVirtualOffset
348 /// tells if a virtual base adjustment is needed in order to get the offset
349 /// of the base subobject.
350 virtual llvm::Value *getVTableAddressPointInStructor(
351 CodeGenFunction &CGF, const CXXRecordDecl *RD, BaseSubobject Base,
352 const CXXRecordDecl *NearestVBase, bool &NeedsVirtualOffset) = 0;
354 /// Get the address point of the vtable for the given base subobject while
355 /// building a constexpr.
356 virtual llvm::Constant *
357 getVTableAddressPointForConstExpr(BaseSubobject Base,
358 const CXXRecordDecl *VTableClass) = 0;
360 /// Get the address of the vtable for the given record decl which should be
361 /// used for the vptr at the given offset in RD.
362 virtual llvm::GlobalVariable *getAddrOfVTable(const CXXRecordDecl *RD,
363 CharUnits VPtrOffset) = 0;
365 /// Build a virtual function pointer in the ABI-specific way.
366 virtual llvm::Value *getVirtualFunctionPointer(CodeGenFunction &CGF,
370 SourceLocation Loc) = 0;
372 /// Emit the ABI-specific virtual destructor call.
373 virtual llvm::Value *
374 EmitVirtualDestructorCall(CodeGenFunction &CGF, const CXXDestructorDecl *Dtor,
375 CXXDtorType DtorType, llvm::Value *This,
376 const CXXMemberCallExpr *CE) = 0;
378 virtual void adjustCallArgsForDestructorThunk(CodeGenFunction &CGF,
380 CallArgList &CallArgs) {}
382 /// Emit any tables needed to implement virtual inheritance. For Itanium,
383 /// this emits virtual table tables. For the MSVC++ ABI, this emits virtual
385 virtual void emitVirtualInheritanceTables(const CXXRecordDecl *RD) = 0;
387 virtual void setThunkLinkage(llvm::Function *Thunk, bool ForVTable,
388 GlobalDecl GD, bool ReturnAdjustment) = 0;
390 virtual llvm::Value *performThisAdjustment(CodeGenFunction &CGF,
392 const ThisAdjustment &TA) = 0;
394 virtual llvm::Value *performReturnAdjustment(CodeGenFunction &CGF,
396 const ReturnAdjustment &RA) = 0;
398 virtual void EmitReturnFromThunk(CodeGenFunction &CGF,
399 RValue RV, QualType ResultType);
401 virtual size_t getSrcArgforCopyCtor(const CXXConstructorDecl *,
402 FunctionArgList &Args) const = 0;
404 /// Gets the pure virtual member call function.
405 virtual StringRef GetPureVirtualCallName() = 0;
407 /// Gets the deleted virtual member call name.
408 virtual StringRef GetDeletedVirtualCallName() = 0;
410 /**************************** Array cookies ******************************/
412 /// Returns the extra size required in order to store the array
413 /// cookie for the given new-expression. May return 0 to indicate that no
414 /// array cookie is required.
416 /// Several cases are filtered out before this method is called:
417 /// - non-array allocations never need a cookie
418 /// - calls to \::operator new(size_t, void*) never need a cookie
420 /// \param expr - the new-expression being allocated.
421 virtual CharUnits GetArrayCookieSize(const CXXNewExpr *expr);
423 /// Initialize the array cookie for the given allocation.
425 /// \param NewPtr - a char* which is the presumed-non-null
426 /// return value of the allocation function
427 /// \param NumElements - the computed number of elements,
428 /// potentially collapsed from the multidimensional array case;
430 /// \param ElementType - the base element allocated type,
431 /// i.e. the allocated type after stripping all array types
432 virtual llvm::Value *InitializeArrayCookie(CodeGenFunction &CGF,
434 llvm::Value *NumElements,
435 const CXXNewExpr *expr,
436 QualType ElementType);
438 /// Reads the array cookie associated with the given pointer,
441 /// \param Ptr - a pointer to the first element in the array
442 /// \param ElementType - the base element type of elements of the array
443 /// \param NumElements - an out parameter which will be initialized
444 /// with the number of elements allocated, or zero if there is no
446 /// \param AllocPtr - an out parameter which will be initialized
447 /// with a char* pointing to the address returned by the allocation
449 /// \param CookieSize - an out parameter which will be initialized
450 /// with the size of the cookie, or zero if there is no cookie
451 virtual void ReadArrayCookie(CodeGenFunction &CGF, llvm::Value *Ptr,
452 const CXXDeleteExpr *expr,
453 QualType ElementType, llvm::Value *&NumElements,
454 llvm::Value *&AllocPtr, CharUnits &CookieSize);
456 /// Return whether the given global decl needs a VTT parameter.
457 virtual bool NeedsVTTParameter(GlobalDecl GD);
460 /// Returns the extra size required in order to store the array
461 /// cookie for the given type. Assumes that an array cookie is
463 virtual CharUnits getArrayCookieSizeImpl(QualType elementType);
465 /// Reads the array cookie for an allocation which is known to have one.
466 /// This is called by the standard implementation of ReadArrayCookie.
468 /// \param ptr - a pointer to the allocation made for an array, as a char*
469 /// \param cookieSize - the computed cookie size of an array
471 /// Other parameters are as above.
474 virtual llvm::Value *readArrayCookieImpl(CodeGenFunction &IGF,
476 CharUnits cookieSize);
480 /*************************** Static local guards ****************************/
482 /// Emits the guarded initializer and destructor setup for the given
483 /// variable, given that it couldn't be emitted as a constant.
484 /// If \p PerformInit is false, the initialization has been folded to a
485 /// constant and should not be performed.
487 /// The variable may be:
488 /// - a static local variable
489 /// - a static data member of a class template instantiation
490 virtual void EmitGuardedInit(CodeGenFunction &CGF, const VarDecl &D,
491 llvm::GlobalVariable *DeclPtr,
492 bool PerformInit) = 0;
494 /// Emit code to force the execution of a destructor during global
495 /// teardown. The default implementation of this uses atexit.
497 /// \param Dtor - a function taking a single pointer argument
498 /// \param Addr - a pointer to pass to the destructor function.
499 virtual void registerGlobalDtor(CodeGenFunction &CGF, const VarDecl &D,
500 llvm::Constant *Dtor,
501 llvm::Constant *Addr) = 0;
503 /*************************** thread_local initialization ********************/
505 /// Emits ABI-required functions necessary to initialize thread_local
506 /// variables in this translation unit.
508 /// \param CXXThreadLocals - The thread_local declarations in this translation
510 /// \param CXXThreadLocalInits - If this translation unit contains any
511 /// non-constant initialization or non-trivial destruction for
512 /// thread_local variables, a list of functions to perform the
514 virtual void EmitThreadLocalInitFuncs(
516 ArrayRef<std::pair<const VarDecl *, llvm::GlobalVariable *>>
518 ArrayRef<llvm::Function *> CXXThreadLocalInits,
519 ArrayRef<llvm::GlobalVariable *> CXXThreadLocalInitVars) = 0;
521 // Determine if references to thread_local global variables can be made
522 // directly or require access through a thread wrapper function.
523 virtual bool usesThreadWrapperFunction() const = 0;
525 /// Emit a reference to a non-local thread_local variable (including
526 /// triggering the initialization of all thread_local variables in its
527 /// translation unit).
528 virtual LValue EmitThreadLocalVarDeclLValue(CodeGenFunction &CGF,
530 QualType LValType) = 0;
532 /// Emit a single constructor/destructor with the given type from a C++
533 /// constructor Decl.
534 virtual void emitCXXStructor(const CXXMethodDecl *MD, StructorType Type) = 0;
537 // Create an instance of a C++ ABI class:
539 /// Creates an Itanium-family ABI.
540 CGCXXABI *CreateItaniumCXXABI(CodeGenModule &CGM);
542 /// Creates a Microsoft-family ABI.
543 CGCXXABI *CreateMicrosoftCXXABI(CodeGenModule &CGM);