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 * 383 getThisArgumentTypeForMethod(const CXXMethodDecl *MD) { 384 return MD->getParent(); 385 } 386 387 /// Perform ABI-specific "this" argument adjustment required prior to 388 /// a call of a virtual function. 389 /// The "VirtualCall" argument is true iff the call itself is virtual. 390 virtual Address 391 adjustThisArgumentForVirtualFunctionCall(CodeGenFunction &CGF, GlobalDecl GD, 392 Address This, bool VirtualCall) { 393 return This; 394 } 395 396 /// Build a parameter variable suitable for 'this'. 397 void buildThisParam(CodeGenFunction &CGF, FunctionArgList &Params); 398 399 /// Insert any ABI-specific implicit parameters into the parameter list for a 400 /// function. This generally involves extra data for constructors and 401 /// destructors. 402 /// 403 /// ABIs may also choose to override the return type, which has been 404 /// initialized with the type of 'this' if HasThisReturn(CGF.CurGD) is true or 405 /// the formal return type of the function otherwise. 406 virtual void addImplicitStructorParams(CodeGenFunction &CGF, QualType &ResTy, 407 FunctionArgList &Params) = 0; 408 409 /// Get the ABI-specific "this" parameter adjustment to apply in the prologue 410 /// of a virtual function. 411 virtual CharUnits getVirtualFunctionPrologueThisAdjustment(GlobalDecl GD) { 412 return CharUnits::Zero(); 413 } 414 415 /// Emit the ABI-specific prolog for the function. 416 virtual void EmitInstanceFunctionProlog(CodeGenFunction &CGF) = 0; 417 418 virtual AddedStructorArgs 419 getImplicitConstructorArgs(CodeGenFunction &CGF, const CXXConstructorDecl *D, 420 CXXCtorType Type, bool ForVirtualBase, 421 bool Delegating) = 0; 422 423 /// Add any ABI-specific implicit arguments needed to call a constructor. 424 /// 425 /// \return The number of arguments added at the beginning and end of the 426 /// call, which is typically zero or one. 427 AddedStructorArgCounts 428 addImplicitConstructorArgs(CodeGenFunction &CGF, const CXXConstructorDecl *D, 429 CXXCtorType Type, bool ForVirtualBase, 430 bool Delegating, CallArgList &Args); 431 432 /// Get the implicit (second) parameter that comes after the "this" pointer, 433 /// or nullptr if there is isn't one. 434 virtual llvm::Value * 435 getCXXDestructorImplicitParam(CodeGenFunction &CGF, 436 const CXXDestructorDecl *DD, CXXDtorType Type, 437 bool ForVirtualBase, bool Delegating) = 0; 438 439 /// Emit the destructor call. 440 virtual void EmitDestructorCall(CodeGenFunction &CGF, 441 const CXXDestructorDecl *DD, CXXDtorType Type, 442 bool ForVirtualBase, bool Delegating, 443 Address This, QualType ThisTy) = 0; 444 445 /// Emits the VTable definitions required for the given record type. 446 virtual void emitVTableDefinitions(CodeGenVTables &CGVT, 447 const CXXRecordDecl *RD) = 0; 448 449 /// Checks if ABI requires extra virtual offset for vtable field. 450 virtual bool 451 isVirtualOffsetNeededForVTableField(CodeGenFunction &CGF, 452 CodeGenFunction::VPtr Vptr) = 0; 453 454 /// Checks if ABI requires to initialize vptrs for given dynamic class. 455 virtual bool doStructorsInitializeVPtrs(const CXXRecordDecl *VTableClass) = 0; 456 457 /// Get the address point of the vtable for the given base subobject. 458 virtual llvm::Constant * 459 getVTableAddressPoint(BaseSubobject Base, 460 const CXXRecordDecl *VTableClass) = 0; 461 462 /// Get the address point of the vtable for the given base subobject while 463 /// building a constructor or a destructor. 464 virtual llvm::Value * 465 getVTableAddressPointInStructor(CodeGenFunction &CGF, const CXXRecordDecl *RD, 466 BaseSubobject Base, 467 const CXXRecordDecl *NearestVBase) = 0; 468 469 /// Get the address point of the vtable for the given base subobject while 470 /// building a constexpr. 471 virtual llvm::Constant * 472 getVTableAddressPointForConstExpr(BaseSubobject Base, 473 const CXXRecordDecl *VTableClass) = 0; 474 475 /// Get the address of the vtable for the given record decl which should be 476 /// used for the vptr at the given offset in RD. 477 virtual llvm::GlobalVariable *getAddrOfVTable(const CXXRecordDecl *RD, 478 CharUnits VPtrOffset) = 0; 479 480 /// Build a virtual function pointer in the ABI-specific way. 481 virtual CGCallee getVirtualFunctionPointer(CodeGenFunction &CGF, 482 GlobalDecl GD, Address This, 483 llvm::Type *Ty, 484 SourceLocation Loc) = 0; 485 486 using DeleteOrMemberCallExpr = 487 llvm::PointerUnion<const CXXDeleteExpr *, const CXXMemberCallExpr *>; 488 489 /// Emit the ABI-specific virtual destructor call. 490 virtual llvm::Value *EmitVirtualDestructorCall(CodeGenFunction &CGF, 491 const CXXDestructorDecl *Dtor, 492 CXXDtorType DtorType, 493 Address This, 494 DeleteOrMemberCallExpr E) = 0; 495 496 virtual void adjustCallArgsForDestructorThunk(CodeGenFunction &CGF, 497 GlobalDecl GD, 498 CallArgList &CallArgs) {} 499 500 /// Emit any tables needed to implement virtual inheritance. For Itanium, 501 /// this emits virtual table tables. For the MSVC++ ABI, this emits virtual 502 /// base tables. 503 virtual void emitVirtualInheritanceTables(const CXXRecordDecl *RD) = 0; 504 505 virtual bool exportThunk() = 0; 506 virtual void setThunkLinkage(llvm::Function *Thunk, bool ForVTable, 507 GlobalDecl GD, bool ReturnAdjustment) = 0; 508 509 virtual llvm::Value *performThisAdjustment(CodeGenFunction &CGF, 510 Address This, 511 const ThisAdjustment &TA) = 0; 512 513 virtual llvm::Value *performReturnAdjustment(CodeGenFunction &CGF, 514 Address Ret, 515 const ReturnAdjustment &RA) = 0; 516 517 virtual void EmitReturnFromThunk(CodeGenFunction &CGF, 518 RValue RV, QualType ResultType); 519 520 virtual size_t getSrcArgforCopyCtor(const CXXConstructorDecl *, 521 FunctionArgList &Args) const = 0; 522 523 /// Gets the offsets of all the virtual base pointers in a given class. 524 virtual std::vector<CharUnits> getVBPtrOffsets(const CXXRecordDecl *RD); 525 526 /// Gets the pure virtual member call function. 527 virtual StringRef GetPureVirtualCallName() = 0; 528 529 /// Gets the deleted virtual member call name. 530 virtual StringRef GetDeletedVirtualCallName() = 0; 531 532 /**************************** Array cookies ******************************/ 533 534 /// Returns the extra size required in order to store the array 535 /// cookie for the given new-expression. May return 0 to indicate that no 536 /// array cookie is required. 537 /// 538 /// Several cases are filtered out before this method is called: 539 /// - non-array allocations never need a cookie 540 /// - calls to \::operator new(size_t, void*) never need a cookie 541 /// 542 /// \param expr - the new-expression being allocated. 543 virtual CharUnits GetArrayCookieSize(const CXXNewExpr *expr); 544 545 /// Initialize the array cookie for the given allocation. 546 /// 547 /// \param NewPtr - a char* which is the presumed-non-null 548 /// return value of the allocation function 549 /// \param NumElements - the computed number of elements, 550 /// potentially collapsed from the multidimensional array case; 551 /// always a size_t 552 /// \param ElementType - the base element allocated type, 553 /// i.e. the allocated type after stripping all array types 554 virtual Address InitializeArrayCookie(CodeGenFunction &CGF, 555 Address NewPtr, 556 llvm::Value *NumElements, 557 const CXXNewExpr *expr, 558 QualType ElementType); 559 560 /// Reads the array cookie associated with the given pointer, 561 /// if it has one. 562 /// 563 /// \param Ptr - a pointer to the first element in the array 564 /// \param ElementType - the base element type of elements of the array 565 /// \param NumElements - an out parameter which will be initialized 566 /// with the number of elements allocated, or zero if there is no 567 /// cookie 568 /// \param AllocPtr - an out parameter which will be initialized 569 /// with a char* pointing to the address returned by the allocation 570 /// function 571 /// \param CookieSize - an out parameter which will be initialized 572 /// with the size of the cookie, or zero if there is no cookie 573 virtual void ReadArrayCookie(CodeGenFunction &CGF, Address Ptr, 574 const CXXDeleteExpr *expr, 575 QualType ElementType, llvm::Value *&NumElements, 576 llvm::Value *&AllocPtr, CharUnits &CookieSize); 577 578 /// Return whether the given global decl needs a VTT parameter. 579 virtual bool NeedsVTTParameter(GlobalDecl GD); 580 581 protected: 582 /// Returns the extra size required in order to store the array 583 /// cookie for the given type. Assumes that an array cookie is 584 /// required. 585 virtual CharUnits getArrayCookieSizeImpl(QualType elementType); 586 587 /// Reads the array cookie for an allocation which is known to have one. 588 /// This is called by the standard implementation of ReadArrayCookie. 589 /// 590 /// \param ptr - a pointer to the allocation made for an array, as a char* 591 /// \param cookieSize - the computed cookie size of an array 592 /// 593 /// Other parameters are as above. 594 /// 595 /// \return a size_t 596 virtual llvm::Value *readArrayCookieImpl(CodeGenFunction &IGF, Address ptr, 597 CharUnits cookieSize); 598 599 public: 600 601 /*************************** Static local guards ****************************/ 602 603 /// Emits the guarded initializer and destructor setup for the given 604 /// variable, given that it couldn't be emitted as a constant. 605 /// If \p PerformInit is false, the initialization has been folded to a 606 /// constant and should not be performed. 607 /// 608 /// The variable may be: 609 /// - a static local variable 610 /// - a static data member of a class template instantiation 611 virtual void EmitGuardedInit(CodeGenFunction &CGF, const VarDecl &D, 612 llvm::GlobalVariable *DeclPtr, 613 bool PerformInit) = 0; 614 615 /// Emit code to force the execution of a destructor during global 616 /// teardown. The default implementation of this uses atexit. 617 /// 618 /// \param Dtor - a function taking a single pointer argument 619 /// \param Addr - a pointer to pass to the destructor function. 620 virtual void registerGlobalDtor(CodeGenFunction &CGF, const VarDecl &D, 621 llvm::FunctionCallee Dtor, 622 llvm::Constant *Addr) = 0; 623 624 /*************************** thread_local initialization ********************/ 625 626 /// Emits ABI-required functions necessary to initialize thread_local 627 /// variables in this translation unit. 628 /// 629 /// \param CXXThreadLocals - The thread_local declarations in this translation 630 /// unit. 631 /// \param CXXThreadLocalInits - If this translation unit contains any 632 /// non-constant initialization or non-trivial destruction for 633 /// thread_local variables, a list of functions to perform the 634 /// initialization. 635 virtual void EmitThreadLocalInitFuncs( 636 CodeGenModule &CGM, ArrayRef<const VarDecl *> CXXThreadLocals, 637 ArrayRef<llvm::Function *> CXXThreadLocalInits, 638 ArrayRef<const VarDecl *> CXXThreadLocalInitVars) = 0; 639 640 // Determine if references to thread_local global variables can be made 641 // directly or require access through a thread wrapper function. 642 virtual bool usesThreadWrapperFunction(const VarDecl *VD) const = 0; 643 644 /// Emit a reference to a non-local thread_local variable (including 645 /// triggering the initialization of all thread_local variables in its 646 /// translation unit). 647 virtual LValue EmitThreadLocalVarDeclLValue(CodeGenFunction &CGF, 648 const VarDecl *VD, 649 QualType LValType) = 0; 650 651 /// Emit a single constructor/destructor with the given type from a C++ 652 /// constructor Decl. 653 virtual void emitCXXStructor(GlobalDecl GD) = 0; 654 655 /// Load a vtable from This, an object of polymorphic type RD, or from one of 656 /// its virtual bases if it does not have its own vtable. Returns the vtable 657 /// and the class from which the vtable was loaded. 658 virtual std::pair<llvm::Value *, const CXXRecordDecl *> 659 LoadVTablePtr(CodeGenFunction &CGF, Address This, 660 const CXXRecordDecl *RD) = 0; 661 }; 662 663 // Create an instance of a C++ ABI class: 664 665 /// Creates an Itanium-family ABI. 666 CGCXXABI *CreateItaniumCXXABI(CodeGenModule &CGM); 667 668 /// Creates a Microsoft-family ABI. 669 CGCXXABI *CreateMicrosoftCXXABI(CodeGenModule &CGM); 670 671 struct CatchRetScope final : EHScopeStack::Cleanup { 672 llvm::CatchPadInst *CPI; 673 674 CatchRetScope(llvm::CatchPadInst *CPI) : CPI(CPI) {} 675 676 void Emit(CodeGenFunction &CGF, Flags flags) override { 677 llvm::BasicBlock *BB = CGF.createBasicBlock("catchret.dest"); 678 CGF.Builder.CreateCatchRet(CPI, BB); 679 CGF.EmitBlock(BB); 680 } 681 }; 682 } 683 } 684 685 #endif 686