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;
42 /// \brief Implements C++ ABI-specific code generation functions.
46 std::unique_ptr<MangleContext> MangleCtx;
48 CGCXXABI(CodeGenModule &CGM)
49 : CGM(CGM), MangleCtx(CGM.getContext().createMangleContext()) {}
52 ImplicitParamDecl *getThisDecl(CodeGenFunction &CGF) {
53 return CGF.CXXABIThisDecl;
55 llvm::Value *getThisValue(CodeGenFunction &CGF) {
56 return CGF.CXXABIThisValue;
58 Address getThisAddress(CodeGenFunction &CGF) {
59 return Address(CGF.CXXABIThisValue, CGF.CXXABIThisAlignment);
62 /// Issue a diagnostic about unsupported features in the ABI.
63 void ErrorUnsupportedABI(CodeGenFunction &CGF, StringRef S);
65 /// Get a null value for unsupported member pointers.
66 llvm::Constant *GetBogusMemberPointer(QualType T);
68 ImplicitParamDecl *&getStructorImplicitParamDecl(CodeGenFunction &CGF) {
69 return CGF.CXXStructorImplicitParamDecl;
71 llvm::Value *&getStructorImplicitParamValue(CodeGenFunction &CGF) {
72 return CGF.CXXStructorImplicitParamValue;
75 /// Perform prolog initialization of the parameter variable suitable
76 /// for 'this' emitted by buildThisParam.
77 void EmitThisParam(CodeGenFunction &CGF);
79 ASTContext &getContext() const { return CGM.getContext(); }
81 virtual bool requiresArrayCookie(const CXXDeleteExpr *E, QualType eltType);
82 virtual bool requiresArrayCookie(const CXXNewExpr *E);
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;
94 /// Gets the mangle context.
95 MangleContext &getMangleContext() {
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).
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.
105 virtual bool HasThisReturn(GlobalDecl GD) const { return false; }
107 virtual bool hasMostDerivedReturn(GlobalDecl GD) const { return false; }
109 /// Returns true if the target allows calling a function through a pointer
110 /// with a different signature than the actual function (or equivalently,
111 /// bitcasting a function or function pointer to a different function type).
112 /// In principle in the most general case this could depend on the target, the
113 /// calling convention, and the actual types of the arguments and return
114 /// value. Here it just means whether the signature mismatch could *ever* be
115 /// allowed; in other words, does the target do strict checking of signatures
117 virtual bool canCallMismatchedFunctionType() const { return true; }
119 /// If the C++ ABI requires the given type be returned in a particular way,
120 /// this method sets RetAI and returns true.
121 virtual bool classifyReturnType(CGFunctionInfo &FI) const = 0;
123 /// Specify how one should pass an argument of a record type.
125 /// Pass it using the normal C aggregate rules for the ABI, potentially
126 /// introducing extra copies and passing some or all of it in registers.
129 /// Pass it on the stack using its defined layout. The argument must be
130 /// evaluated directly into the correct stack position in the arguments area,
131 /// and the call machinery must not move it or introduce extra copies.
134 /// Pass it as a pointer to temporary memory.
138 /// Returns true if C++ allows us to copy the memory of an object of type RD
139 /// when it is passed as an argument.
140 bool canCopyArgument(const CXXRecordDecl *RD) const;
142 /// Returns how an argument of the given record type should be passed.
143 virtual RecordArgABI getRecordArgABI(const CXXRecordDecl *RD) const = 0;
145 /// Returns true if the implicit 'sret' parameter comes after the implicit
146 /// 'this' parameter of C++ instance methods.
147 virtual bool isSRetParameterAfterThis() const { return false; }
149 /// Find the LLVM type used to represent the given member pointer
152 ConvertMemberPointerType(const MemberPointerType *MPT);
154 /// Load a member function from an object and a member function
155 /// pointer. Apply the this-adjustment and set 'This' to the
157 virtual llvm::Value *EmitLoadOfMemberFunctionPointer(
158 CodeGenFunction &CGF, const Expr *E, Address This,
159 llvm::Value *&ThisPtrForCall, llvm::Value *MemPtr,
160 const MemberPointerType *MPT);
162 /// Calculate an l-value from an object and a data member pointer.
163 virtual llvm::Value *
164 EmitMemberDataPointerAddress(CodeGenFunction &CGF, const Expr *E,
165 Address Base, llvm::Value *MemPtr,
166 const MemberPointerType *MPT);
168 /// Perform a derived-to-base, base-to-derived, or bitcast member
169 /// pointer conversion.
170 virtual llvm::Value *EmitMemberPointerConversion(CodeGenFunction &CGF,
174 /// Perform a derived-to-base, base-to-derived, or bitcast member
175 /// pointer conversion on a constant value.
176 virtual llvm::Constant *EmitMemberPointerConversion(const CastExpr *E,
177 llvm::Constant *Src);
179 /// Return true if the given member pointer can be zero-initialized
180 /// (in the C++ sense) with an LLVM zeroinitializer.
181 virtual bool isZeroInitializable(const MemberPointerType *MPT);
183 /// Return whether or not a member pointers type is convertible to an IR type.
184 virtual bool isMemberPointerConvertible(const MemberPointerType *MPT) const {
188 /// Create a null member pointer of the given type.
189 virtual llvm::Constant *EmitNullMemberPointer(const MemberPointerType *MPT);
191 /// Create a member pointer for the given method.
192 virtual llvm::Constant *EmitMemberFunctionPointer(const CXXMethodDecl *MD);
194 /// Create a member pointer for the given field.
195 virtual llvm::Constant *EmitMemberDataPointer(const MemberPointerType *MPT,
198 /// Create a member pointer for the given member pointer constant.
199 virtual llvm::Constant *EmitMemberPointer(const APValue &MP, QualType MPT);
201 /// Emit a comparison between two member pointers. Returns an i1.
202 virtual llvm::Value *
203 EmitMemberPointerComparison(CodeGenFunction &CGF,
206 const MemberPointerType *MPT,
209 /// Determine if a member pointer is non-null. Returns an i1.
210 virtual llvm::Value *
211 EmitMemberPointerIsNotNull(CodeGenFunction &CGF,
213 const MemberPointerType *MPT);
216 /// A utility method for computing the offset required for the given
217 /// base-to-derived or derived-to-base member-pointer conversion.
218 /// Does not handle virtual conversions (in case we ever fully
219 /// support an ABI that allows this). Returns null if no adjustment
221 llvm::Constant *getMemberPointerAdjustment(const CastExpr *E);
223 /// \brief Computes the non-virtual adjustment needed for a member pointer
224 /// conversion along an inheritance path stored in an APValue. Unlike
225 /// getMemberPointerAdjustment(), the adjustment can be negative if the path
226 /// is from a derived type to a base type.
227 CharUnits getMemberPointerPathAdjustment(const APValue &MP);
230 virtual void emitVirtualObjectDelete(CodeGenFunction &CGF,
231 const CXXDeleteExpr *DE,
232 Address Ptr, QualType ElementType,
233 const CXXDestructorDecl *Dtor) = 0;
234 virtual void emitRethrow(CodeGenFunction &CGF, bool isNoReturn) = 0;
235 virtual void emitThrow(CodeGenFunction &CGF, const CXXThrowExpr *E) = 0;
236 virtual llvm::GlobalVariable *getThrowInfo(QualType T) { return nullptr; }
238 /// \brief Determine whether it's possible to emit a vtable for \p RD, even
239 /// though we do not know that the vtable has been marked as used by semantic
241 virtual bool canSpeculativelyEmitVTable(const CXXRecordDecl *RD) const = 0;
243 virtual void emitBeginCatch(CodeGenFunction &CGF, const CXXCatchStmt *C) = 0;
245 virtual llvm::CallInst *
246 emitTerminateForUnexpectedException(CodeGenFunction &CGF,
249 virtual llvm::Constant *getAddrOfRTTIDescriptor(QualType Ty) = 0;
250 virtual CatchTypeInfo
251 getAddrOfCXXCatchHandlerType(QualType Ty, QualType CatchHandlerType) = 0;
252 virtual CatchTypeInfo getCatchAllTypeInfo();
254 virtual bool shouldTypeidBeNullChecked(bool IsDeref,
255 QualType SrcRecordTy) = 0;
256 virtual void EmitBadTypeidCall(CodeGenFunction &CGF) = 0;
257 virtual llvm::Value *EmitTypeid(CodeGenFunction &CGF, QualType SrcRecordTy,
259 llvm::Type *StdTypeInfoPtrTy) = 0;
261 virtual bool shouldDynamicCastCallBeNullChecked(bool SrcIsPtr,
262 QualType SrcRecordTy) = 0;
264 virtual llvm::Value *
265 EmitDynamicCastCall(CodeGenFunction &CGF, Address Value,
266 QualType SrcRecordTy, QualType DestTy,
267 QualType DestRecordTy, llvm::BasicBlock *CastEnd) = 0;
269 virtual llvm::Value *EmitDynamicCastToVoid(CodeGenFunction &CGF,
271 QualType SrcRecordTy,
272 QualType DestTy) = 0;
274 virtual bool EmitBadCastCall(CodeGenFunction &CGF) = 0;
276 virtual llvm::Value *GetVirtualBaseClassOffset(CodeGenFunction &CGF,
278 const CXXRecordDecl *ClassDecl,
279 const CXXRecordDecl *BaseClassDecl) = 0;
281 virtual llvm::BasicBlock *EmitCtorCompleteObjectHandler(CodeGenFunction &CGF,
282 const CXXRecordDecl *RD);
284 /// Emit the code to initialize hidden members required
285 /// to handle virtual inheritance, if needed by the ABI.
287 initializeHiddenVirtualInheritanceMembers(CodeGenFunction &CGF,
288 const CXXRecordDecl *RD) {}
290 /// Emit constructor variants required by this ABI.
291 virtual void EmitCXXConstructors(const CXXConstructorDecl *D) = 0;
293 /// Build the signature of the given constructor or destructor variant by
294 /// adding any required parameters. For convenience, ArgTys has been
295 /// initialized with the type of 'this'.
296 virtual void buildStructorSignature(const CXXMethodDecl *MD, StructorType T,
297 SmallVectorImpl<CanQualType> &ArgTys) = 0;
299 /// Returns true if the given destructor type should be emitted as a linkonce
300 /// delegating thunk, regardless of whether the dtor is defined in this TU or
302 virtual bool useThunkForDtorVariant(const CXXDestructorDecl *Dtor,
303 CXXDtorType DT) const = 0;
305 /// Emit destructor variants required by this ABI.
306 virtual void EmitCXXDestructors(const CXXDestructorDecl *D) = 0;
308 /// Get the type of the implicit "this" parameter used by a method. May return
309 /// zero if no specific type is applicable, e.g. if the ABI expects the "this"
310 /// parameter to point to some artificial offset in a complete object due to
311 /// vbases being reordered.
312 virtual const CXXRecordDecl *
313 getThisArgumentTypeForMethod(const CXXMethodDecl *MD) {
314 return MD->getParent();
317 /// Perform ABI-specific "this" argument adjustment required prior to
318 /// a call of a virtual function.
319 /// The "VirtualCall" argument is true iff the call itself is virtual.
321 adjustThisArgumentForVirtualFunctionCall(CodeGenFunction &CGF, GlobalDecl GD,
322 Address This, bool VirtualCall) {
326 /// Build a parameter variable suitable for 'this'.
327 void buildThisParam(CodeGenFunction &CGF, FunctionArgList &Params);
329 /// Insert any ABI-specific implicit parameters into the parameter list for a
330 /// function. This generally involves extra data for constructors and
333 /// ABIs may also choose to override the return type, which has been
334 /// initialized with the type of 'this' if HasThisReturn(CGF.CurGD) is true or
335 /// the formal return type of the function otherwise.
336 virtual void addImplicitStructorParams(CodeGenFunction &CGF, QualType &ResTy,
337 FunctionArgList &Params) = 0;
339 /// Get the ABI-specific "this" parameter adjustment to apply in the prologue
340 /// of a virtual function.
341 virtual CharUnits getVirtualFunctionPrologueThisAdjustment(GlobalDecl GD) {
342 return CharUnits::Zero();
345 /// Perform ABI-specific "this" parameter adjustment in a virtual function
347 virtual llvm::Value *adjustThisParameterInVirtualFunctionPrologue(
348 CodeGenFunction &CGF, GlobalDecl GD, llvm::Value *This) {
352 /// Emit the ABI-specific prolog for the function.
353 virtual void EmitInstanceFunctionProlog(CodeGenFunction &CGF) = 0;
355 /// Add any ABI-specific implicit arguments needed to call a constructor.
357 /// \return The number of args added to the call, which is typically zero or
360 addImplicitConstructorArgs(CodeGenFunction &CGF, const CXXConstructorDecl *D,
361 CXXCtorType Type, bool ForVirtualBase,
362 bool Delegating, CallArgList &Args) = 0;
364 /// Emit the destructor call.
365 virtual void EmitDestructorCall(CodeGenFunction &CGF,
366 const CXXDestructorDecl *DD, CXXDtorType Type,
367 bool ForVirtualBase, bool Delegating,
370 /// Emits the VTable definitions required for the given record type.
371 virtual void emitVTableDefinitions(CodeGenVTables &CGVT,
372 const CXXRecordDecl *RD) = 0;
374 /// Checks if ABI requires extra virtual offset for vtable field.
376 isVirtualOffsetNeededForVTableField(CodeGenFunction &CGF,
377 CodeGenFunction::VPtr Vptr) = 0;
379 /// Checks if ABI requires to initilize vptrs for given dynamic class.
380 virtual bool doStructorsInitializeVPtrs(const CXXRecordDecl *VTableClass) = 0;
382 /// Get the address point of the vtable for the given base subobject.
383 virtual llvm::Constant *
384 getVTableAddressPoint(BaseSubobject Base,
385 const CXXRecordDecl *VTableClass) = 0;
387 /// Get the address point of the vtable for the given base subobject while
388 /// building a constructor or a destructor.
389 virtual llvm::Value *
390 getVTableAddressPointInStructor(CodeGenFunction &CGF, const CXXRecordDecl *RD,
392 const CXXRecordDecl *NearestVBase) = 0;
394 /// Get the address point of the vtable for the given base subobject while
395 /// building a constexpr.
396 virtual llvm::Constant *
397 getVTableAddressPointForConstExpr(BaseSubobject Base,
398 const CXXRecordDecl *VTableClass) = 0;
400 /// Get the address of the vtable for the given record decl which should be
401 /// used for the vptr at the given offset in RD.
402 virtual llvm::GlobalVariable *getAddrOfVTable(const CXXRecordDecl *RD,
403 CharUnits VPtrOffset) = 0;
405 /// Build a virtual function pointer in the ABI-specific way.
406 virtual llvm::Value *getVirtualFunctionPointer(CodeGenFunction &CGF,
410 SourceLocation Loc) = 0;
412 /// Emit the ABI-specific virtual destructor call.
413 virtual llvm::Value *
414 EmitVirtualDestructorCall(CodeGenFunction &CGF, const CXXDestructorDecl *Dtor,
415 CXXDtorType DtorType, Address This,
416 const CXXMemberCallExpr *CE) = 0;
418 virtual void adjustCallArgsForDestructorThunk(CodeGenFunction &CGF,
420 CallArgList &CallArgs) {}
422 /// Emit any tables needed to implement virtual inheritance. For Itanium,
423 /// this emits virtual table tables. For the MSVC++ ABI, this emits virtual
425 virtual void emitVirtualInheritanceTables(const CXXRecordDecl *RD) = 0;
427 virtual void setThunkLinkage(llvm::Function *Thunk, bool ForVTable,
428 GlobalDecl GD, bool ReturnAdjustment) = 0;
430 virtual llvm::Value *performThisAdjustment(CodeGenFunction &CGF,
432 const ThisAdjustment &TA) = 0;
434 virtual llvm::Value *performReturnAdjustment(CodeGenFunction &CGF,
436 const ReturnAdjustment &RA) = 0;
438 virtual void EmitReturnFromThunk(CodeGenFunction &CGF,
439 RValue RV, QualType ResultType);
441 virtual size_t getSrcArgforCopyCtor(const CXXConstructorDecl *,
442 FunctionArgList &Args) const = 0;
444 /// Gets the offsets of all the virtual base pointers in a given class.
445 virtual std::vector<CharUnits> getVBPtrOffsets(const CXXRecordDecl *RD);
447 /// Gets the pure virtual member call function.
448 virtual StringRef GetPureVirtualCallName() = 0;
450 /// Gets the deleted virtual member call name.
451 virtual StringRef GetDeletedVirtualCallName() = 0;
453 /**************************** Array cookies ******************************/
455 /// Returns the extra size required in order to store the array
456 /// cookie for the given new-expression. May return 0 to indicate that no
457 /// array cookie is required.
459 /// Several cases are filtered out before this method is called:
460 /// - non-array allocations never need a cookie
461 /// - calls to \::operator new(size_t, void*) never need a cookie
463 /// \param expr - the new-expression being allocated.
464 virtual CharUnits GetArrayCookieSize(const CXXNewExpr *expr);
466 /// Initialize the array cookie for the given allocation.
468 /// \param NewPtr - a char* which is the presumed-non-null
469 /// return value of the allocation function
470 /// \param NumElements - the computed number of elements,
471 /// potentially collapsed from the multidimensional array case;
473 /// \param ElementType - the base element allocated type,
474 /// i.e. the allocated type after stripping all array types
475 virtual Address InitializeArrayCookie(CodeGenFunction &CGF,
477 llvm::Value *NumElements,
478 const CXXNewExpr *expr,
479 QualType ElementType);
481 /// Reads the array cookie associated with the given pointer,
484 /// \param Ptr - a pointer to the first element in the array
485 /// \param ElementType - the base element type of elements of the array
486 /// \param NumElements - an out parameter which will be initialized
487 /// with the number of elements allocated, or zero if there is no
489 /// \param AllocPtr - an out parameter which will be initialized
490 /// with a char* pointing to the address returned by the allocation
492 /// \param CookieSize - an out parameter which will be initialized
493 /// with the size of the cookie, or zero if there is no cookie
494 virtual void ReadArrayCookie(CodeGenFunction &CGF, Address Ptr,
495 const CXXDeleteExpr *expr,
496 QualType ElementType, llvm::Value *&NumElements,
497 llvm::Value *&AllocPtr, CharUnits &CookieSize);
499 /// Return whether the given global decl needs a VTT parameter.
500 virtual bool NeedsVTTParameter(GlobalDecl GD);
503 /// Returns the extra size required in order to store the array
504 /// cookie for the given type. Assumes that an array cookie is
506 virtual CharUnits getArrayCookieSizeImpl(QualType elementType);
508 /// Reads the array cookie for an allocation which is known to have one.
509 /// This is called by the standard implementation of ReadArrayCookie.
511 /// \param ptr - a pointer to the allocation made for an array, as a char*
512 /// \param cookieSize - the computed cookie size of an array
514 /// Other parameters are as above.
517 virtual llvm::Value *readArrayCookieImpl(CodeGenFunction &IGF, Address ptr,
518 CharUnits cookieSize);
522 /*************************** Static local guards ****************************/
524 /// Emits the guarded initializer and destructor setup for the given
525 /// variable, given that it couldn't be emitted as a constant.
526 /// If \p PerformInit is false, the initialization has been folded to a
527 /// constant and should not be performed.
529 /// The variable may be:
530 /// - a static local variable
531 /// - a static data member of a class template instantiation
532 virtual void EmitGuardedInit(CodeGenFunction &CGF, const VarDecl &D,
533 llvm::GlobalVariable *DeclPtr,
534 bool PerformInit) = 0;
536 /// Emit code to force the execution of a destructor during global
537 /// teardown. The default implementation of this uses atexit.
539 /// \param Dtor - a function taking a single pointer argument
540 /// \param Addr - a pointer to pass to the destructor function.
541 virtual void registerGlobalDtor(CodeGenFunction &CGF, const VarDecl &D,
542 llvm::Constant *Dtor,
543 llvm::Constant *Addr) = 0;
545 /*************************** thread_local initialization ********************/
547 /// Emits ABI-required functions necessary to initialize thread_local
548 /// variables in this translation unit.
550 /// \param CXXThreadLocals - The thread_local declarations in this translation
552 /// \param CXXThreadLocalInits - If this translation unit contains any
553 /// non-constant initialization or non-trivial destruction for
554 /// thread_local variables, a list of functions to perform the
556 virtual void EmitThreadLocalInitFuncs(
557 CodeGenModule &CGM, ArrayRef<const VarDecl *> CXXThreadLocals,
558 ArrayRef<llvm::Function *> CXXThreadLocalInits,
559 ArrayRef<const VarDecl *> CXXThreadLocalInitVars) = 0;
561 // Determine if references to thread_local global variables can be made
562 // directly or require access through a thread wrapper function.
563 virtual bool usesThreadWrapperFunction() const = 0;
565 /// Emit a reference to a non-local thread_local variable (including
566 /// triggering the initialization of all thread_local variables in its
567 /// translation unit).
568 virtual LValue EmitThreadLocalVarDeclLValue(CodeGenFunction &CGF,
570 QualType LValType) = 0;
572 /// Emit a single constructor/destructor with the given type from a C++
573 /// constructor Decl.
574 virtual void emitCXXStructor(const CXXMethodDecl *MD, StructorType Type) = 0;
577 // Create an instance of a C++ ABI class:
579 /// Creates an Itanium-family ABI.
580 CGCXXABI *CreateItaniumCXXABI(CodeGenModule &CGM);
582 /// Creates a Microsoft-family ABI.
583 CGCXXABI *CreateMicrosoftCXXABI(CodeGenModule &CGM);