CGCXXABI.h revision 263508
1//===----- CGCXXABI.h - Interface to C++ ABIs -------------------*- C++ -*-===// 2// 3// The LLVM Compiler Infrastructure 4// 5// This file is distributed under the University of Illinois Open Source 6// License. See LICENSE.TXT for details. 7// 8//===----------------------------------------------------------------------===// 9// 10// This provides an abstract class for C++ code generation. Concrete subclasses 11// of this implement code generation for specific C++ ABIs. 12// 13//===----------------------------------------------------------------------===// 14 15#ifndef CLANG_CODEGEN_CXXABI_H 16#define CLANG_CODEGEN_CXXABI_H 17 18#include "CodeGenFunction.h" 19#include "clang/Basic/LLVM.h" 20 21namespace llvm { 22 class Constant; 23 class Type; 24 class Value; 25} 26 27namespace clang { 28 class CastExpr; 29 class CXXConstructorDecl; 30 class CXXDestructorDecl; 31 class CXXMethodDecl; 32 class CXXRecordDecl; 33 class FieldDecl; 34 class MangleContext; 35 36namespace CodeGen { 37 class CodeGenFunction; 38 class CodeGenModule; 39 40/// \brief Implements C++ ABI-specific code generation functions. 41class CGCXXABI { 42protected: 43 CodeGenModule &CGM; 44 OwningPtr<MangleContext> MangleCtx; 45 46 CGCXXABI(CodeGenModule &CGM) 47 : CGM(CGM), MangleCtx(CGM.getContext().createMangleContext()) {} 48 49protected: 50 ImplicitParamDecl *&getThisDecl(CodeGenFunction &CGF) { 51 return CGF.CXXABIThisDecl; 52 } 53 llvm::Value *&getThisValue(CodeGenFunction &CGF) { 54 return CGF.CXXABIThisValue; 55 } 56 57 /// Issue a diagnostic about unsupported features in the ABI. 58 void ErrorUnsupportedABI(CodeGenFunction &CGF, StringRef S); 59 60 /// Get a null value for unsupported member pointers. 61 llvm::Constant *GetBogusMemberPointer(QualType T); 62 63 // FIXME: Every place that calls getVTT{Decl,Value} is something 64 // that needs to be abstracted properly. 65 ImplicitParamDecl *&getVTTDecl(CodeGenFunction &CGF) { 66 return CGF.CXXStructorImplicitParamDecl; 67 } 68 llvm::Value *&getVTTValue(CodeGenFunction &CGF) { 69 return CGF.CXXStructorImplicitParamValue; 70 } 71 72 ImplicitParamDecl *&getStructorImplicitParamDecl(CodeGenFunction &CGF) { 73 return CGF.CXXStructorImplicitParamDecl; 74 } 75 llvm::Value *&getStructorImplicitParamValue(CodeGenFunction &CGF) { 76 return CGF.CXXStructorImplicitParamValue; 77 } 78 79 /// Build a parameter variable suitable for 'this'. 80 void BuildThisParam(CodeGenFunction &CGF, FunctionArgList &Params); 81 82 /// Perform prolog initialization of the parameter variable suitable 83 /// for 'this' emitted by BuildThisParam. 84 void EmitThisParam(CodeGenFunction &CGF); 85 86 ASTContext &getContext() const { return CGM.getContext(); } 87 88 virtual bool requiresArrayCookie(const CXXDeleteExpr *E, QualType eltType); 89 virtual bool requiresArrayCookie(const CXXNewExpr *E); 90 91public: 92 93 virtual ~CGCXXABI(); 94 95 /// Gets the mangle context. 96 MangleContext &getMangleContext() { 97 return *MangleCtx; 98 } 99 100 /// Returns true if the given constructor or destructor is one of the 101 /// kinds that the ABI says returns 'this' (only applies when called 102 /// non-virtually for destructors). 103 /// 104 /// There currently is no way to indicate if a destructor returns 'this' 105 /// when called virtually, and code generation does not support the case. 106 virtual bool HasThisReturn(GlobalDecl GD) const { return false; } 107 108 /// Returns true if the given record type should be returned indirectly. 109 virtual bool isReturnTypeIndirect(const CXXRecordDecl *RD) const = 0; 110 111 /// Specify how one should pass an argument of a record type. 112 enum RecordArgABI { 113 /// Pass it using the normal C aggregate rules for the ABI, potentially 114 /// introducing extra copies and passing some or all of it in registers. 115 RAA_Default = 0, 116 117 /// Pass it on the stack using its defined layout. The argument must be 118 /// evaluated directly into the correct stack position in the arguments area, 119 /// and the call machinery must not move it or introduce extra copies. 120 RAA_DirectInMemory, 121 122 /// Pass it as a pointer to temporary memory. 123 RAA_Indirect 124 }; 125 126 /// Returns how an argument of the given record type should be passed. 127 virtual RecordArgABI getRecordArgABI(const CXXRecordDecl *RD) const = 0; 128 129 /// Find the LLVM type used to represent the given member pointer 130 /// type. 131 virtual llvm::Type * 132 ConvertMemberPointerType(const MemberPointerType *MPT); 133 134 /// Load a member function from an object and a member function 135 /// pointer. Apply the this-adjustment and set 'This' to the 136 /// adjusted value. 137 virtual llvm::Value * 138 EmitLoadOfMemberFunctionPointer(CodeGenFunction &CGF, 139 llvm::Value *&This, 140 llvm::Value *MemPtr, 141 const MemberPointerType *MPT); 142 143 /// Calculate an l-value from an object and a data member pointer. 144 virtual llvm::Value *EmitMemberDataPointerAddress(CodeGenFunction &CGF, 145 llvm::Value *Base, 146 llvm::Value *MemPtr, 147 const MemberPointerType *MPT); 148 149 /// Perform a derived-to-base, base-to-derived, or bitcast member 150 /// pointer conversion. 151 virtual llvm::Value *EmitMemberPointerConversion(CodeGenFunction &CGF, 152 const CastExpr *E, 153 llvm::Value *Src); 154 155 /// Perform a derived-to-base, base-to-derived, or bitcast member 156 /// pointer conversion on a constant value. 157 virtual llvm::Constant *EmitMemberPointerConversion(const CastExpr *E, 158 llvm::Constant *Src); 159 160 /// Return true if the given member pointer can be zero-initialized 161 /// (in the C++ sense) with an LLVM zeroinitializer. 162 virtual bool isZeroInitializable(const MemberPointerType *MPT); 163 164 /// Create a null member pointer of the given type. 165 virtual llvm::Constant *EmitNullMemberPointer(const MemberPointerType *MPT); 166 167 /// Create a member pointer for the given method. 168 virtual llvm::Constant *EmitMemberPointer(const CXXMethodDecl *MD); 169 170 /// Create a member pointer for the given field. 171 virtual llvm::Constant *EmitMemberDataPointer(const MemberPointerType *MPT, 172 CharUnits offset); 173 174 /// Create a member pointer for the given member pointer constant. 175 virtual llvm::Constant *EmitMemberPointer(const APValue &MP, QualType MPT); 176 177 /// Emit a comparison between two member pointers. Returns an i1. 178 virtual llvm::Value * 179 EmitMemberPointerComparison(CodeGenFunction &CGF, 180 llvm::Value *L, 181 llvm::Value *R, 182 const MemberPointerType *MPT, 183 bool Inequality); 184 185 /// Determine if a member pointer is non-null. Returns an i1. 186 virtual llvm::Value * 187 EmitMemberPointerIsNotNull(CodeGenFunction &CGF, 188 llvm::Value *MemPtr, 189 const MemberPointerType *MPT); 190 191protected: 192 /// A utility method for computing the offset required for the given 193 /// base-to-derived or derived-to-base member-pointer conversion. 194 /// Does not handle virtual conversions (in case we ever fully 195 /// support an ABI that allows this). Returns null if no adjustment 196 /// is required. 197 llvm::Constant *getMemberPointerAdjustment(const CastExpr *E); 198 199 /// \brief Computes the non-virtual adjustment needed for a member pointer 200 /// conversion along an inheritance path stored in an APValue. Unlike 201 /// getMemberPointerAdjustment(), the adjustment can be negative if the path 202 /// is from a derived type to a base type. 203 CharUnits getMemberPointerPathAdjustment(const APValue &MP); 204 205public: 206 /// Adjust the given non-null pointer to an object of polymorphic 207 /// type to point to the complete object. 208 /// 209 /// The IR type of the result should be a pointer but is otherwise 210 /// irrelevant. 211 virtual llvm::Value *adjustToCompleteObject(CodeGenFunction &CGF, 212 llvm::Value *ptr, 213 QualType type) = 0; 214 215 virtual llvm::Value *GetVirtualBaseClassOffset(CodeGenFunction &CGF, 216 llvm::Value *This, 217 const CXXRecordDecl *ClassDecl, 218 const CXXRecordDecl *BaseClassDecl) = 0; 219 220 /// Build the signature of the given constructor variant by adding 221 /// any required parameters. For convenience, ArgTys has been initialized 222 /// with the type of 'this' and ResTy has been initialized with the type of 223 /// 'this' if HasThisReturn(GlobalDecl(Ctor, T)) is true or 'void' otherwise 224 /// (although both may be changed by the ABI). 225 /// 226 /// If there are ever any ABIs where the implicit parameters are 227 /// intermixed with the formal parameters, we can address those 228 /// then. 229 virtual void BuildConstructorSignature(const CXXConstructorDecl *Ctor, 230 CXXCtorType T, 231 CanQualType &ResTy, 232 SmallVectorImpl<CanQualType> &ArgTys) = 0; 233 234 virtual llvm::BasicBlock *EmitCtorCompleteObjectHandler(CodeGenFunction &CGF, 235 const CXXRecordDecl *RD); 236 237 /// Emit the code to initialize hidden members required 238 /// to handle virtual inheritance, if needed by the ABI. 239 virtual void 240 initializeHiddenVirtualInheritanceMembers(CodeGenFunction &CGF, 241 const CXXRecordDecl *RD) {} 242 243 /// Emit constructor variants required by this ABI. 244 virtual void EmitCXXConstructors(const CXXConstructorDecl *D) = 0; 245 246 /// Build the signature of the given destructor variant by adding 247 /// any required parameters. For convenience, ArgTys has been initialized 248 /// with the type of 'this' and ResTy has been initialized with the type of 249 /// 'this' if HasThisReturn(GlobalDecl(Dtor, T)) is true or 'void' otherwise 250 /// (although both may be changed by the ABI). 251 virtual void BuildDestructorSignature(const CXXDestructorDecl *Dtor, 252 CXXDtorType T, 253 CanQualType &ResTy, 254 SmallVectorImpl<CanQualType> &ArgTys) = 0; 255 256 /// Returns true if the given destructor type should be emitted as a linkonce 257 /// delegating thunk, regardless of whether the dtor is defined in this TU or 258 /// not. 259 virtual bool useThunkForDtorVariant(const CXXDestructorDecl *Dtor, 260 CXXDtorType DT) const = 0; 261 262 /// Emit destructor variants required by this ABI. 263 virtual void EmitCXXDestructors(const CXXDestructorDecl *D) = 0; 264 265 /// Get the type of the implicit "this" parameter used by a method. May return 266 /// zero if no specific type is applicable, e.g. if the ABI expects the "this" 267 /// parameter to point to some artificial offset in a complete object due to 268 /// vbases being reordered. 269 virtual const CXXRecordDecl * 270 getThisArgumentTypeForMethod(const CXXMethodDecl *MD) { 271 return MD->getParent(); 272 } 273 274 /// Perform ABI-specific "this" argument adjustment required prior to 275 /// a virtual function call. 276 virtual llvm::Value *adjustThisArgumentForVirtualCall(CodeGenFunction &CGF, 277 GlobalDecl GD, 278 llvm::Value *This) { 279 return This; 280 } 281 282 /// Build the ABI-specific portion of the parameter list for a 283 /// function. This generally involves a 'this' parameter and 284 /// possibly some extra data for constructors and destructors. 285 /// 286 /// ABIs may also choose to override the return type, which has been 287 /// initialized with the type of 'this' if HasThisReturn(CGF.CurGD) is true or 288 /// the formal return type of the function otherwise. 289 virtual void BuildInstanceFunctionParams(CodeGenFunction &CGF, 290 QualType &ResTy, 291 FunctionArgList &Params) = 0; 292 293 /// Perform ABI-specific "this" parameter adjustment in a virtual function 294 /// prologue. 295 virtual llvm::Value *adjustThisParameterInVirtualFunctionPrologue( 296 CodeGenFunction &CGF, GlobalDecl GD, llvm::Value *This) { 297 return This; 298 } 299 300 /// Emit the ABI-specific prolog for the function. 301 virtual void EmitInstanceFunctionProlog(CodeGenFunction &CGF) = 0; 302 303 /// Emit the constructor call. Return the function that is called. 304 virtual void EmitConstructorCall(CodeGenFunction &CGF, 305 const CXXConstructorDecl *D, 306 CXXCtorType Type, 307 bool ForVirtualBase, bool Delegating, 308 llvm::Value *This, 309 CallExpr::const_arg_iterator ArgBeg, 310 CallExpr::const_arg_iterator ArgEnd) = 0; 311 312 /// Emits the VTable definitions required for the given record type. 313 virtual void emitVTableDefinitions(CodeGenVTables &CGVT, 314 const CXXRecordDecl *RD) = 0; 315 316 /// Get the address point of the vtable for the given base subobject while 317 /// building a constructor or a destructor. On return, NeedsVirtualOffset 318 /// tells if a virtual base adjustment is needed in order to get the offset 319 /// of the base subobject. 320 virtual llvm::Value *getVTableAddressPointInStructor( 321 CodeGenFunction &CGF, const CXXRecordDecl *RD, BaseSubobject Base, 322 const CXXRecordDecl *NearestVBase, bool &NeedsVirtualOffset) = 0; 323 324 /// Get the address point of the vtable for the given base subobject while 325 /// building a constexpr. 326 virtual llvm::Constant * 327 getVTableAddressPointForConstExpr(BaseSubobject Base, 328 const CXXRecordDecl *VTableClass) = 0; 329 330 /// Get the address of the vtable for the given record decl which should be 331 /// used for the vptr at the given offset in RD. 332 virtual llvm::GlobalVariable *getAddrOfVTable(const CXXRecordDecl *RD, 333 CharUnits VPtrOffset) = 0; 334 335 /// Build a virtual function pointer in the ABI-specific way. 336 virtual llvm::Value *getVirtualFunctionPointer(CodeGenFunction &CGF, 337 GlobalDecl GD, 338 llvm::Value *This, 339 llvm::Type *Ty) = 0; 340 341 /// Emit the ABI-specific virtual destructor call. 342 virtual void EmitVirtualDestructorCall(CodeGenFunction &CGF, 343 const CXXDestructorDecl *Dtor, 344 CXXDtorType DtorType, 345 SourceLocation CallLoc, 346 llvm::Value *This) = 0; 347 348 virtual void adjustCallArgsForDestructorThunk(CodeGenFunction &CGF, 349 GlobalDecl GD, 350 CallArgList &CallArgs) {} 351 352 /// Emit any tables needed to implement virtual inheritance. For Itanium, 353 /// this emits virtual table tables. For the MSVC++ ABI, this emits virtual 354 /// base tables. 355 virtual void emitVirtualInheritanceTables(const CXXRecordDecl *RD) = 0; 356 357 virtual void setThunkLinkage(llvm::Function *Thunk, bool ForVTable) = 0; 358 359 virtual llvm::Value *performThisAdjustment(CodeGenFunction &CGF, 360 llvm::Value *This, 361 const ThisAdjustment &TA) = 0; 362 363 virtual llvm::Value *performReturnAdjustment(CodeGenFunction &CGF, 364 llvm::Value *Ret, 365 const ReturnAdjustment &RA) = 0; 366 367 virtual void EmitReturnFromThunk(CodeGenFunction &CGF, 368 RValue RV, QualType ResultType); 369 370 /// Gets the pure virtual member call function. 371 virtual StringRef GetPureVirtualCallName() = 0; 372 373 /// Gets the deleted virtual member call name. 374 virtual StringRef GetDeletedVirtualCallName() = 0; 375 376 /// \brief Returns true iff static data members that are initialized in the 377 /// class definition should have linkonce linkage. 378 virtual bool isInlineInitializedStaticDataMemberLinkOnce() { return false; } 379 380 /**************************** Array cookies ******************************/ 381 382 /// Returns the extra size required in order to store the array 383 /// cookie for the given new-expression. May return 0 to indicate that no 384 /// array cookie is required. 385 /// 386 /// Several cases are filtered out before this method is called: 387 /// - non-array allocations never need a cookie 388 /// - calls to \::operator new(size_t, void*) never need a cookie 389 /// 390 /// \param expr - the new-expression being allocated. 391 virtual CharUnits GetArrayCookieSize(const CXXNewExpr *expr); 392 393 /// Initialize the array cookie for the given allocation. 394 /// 395 /// \param NewPtr - a char* which is the presumed-non-null 396 /// return value of the allocation function 397 /// \param NumElements - the computed number of elements, 398 /// potentially collapsed from the multidimensional array case; 399 /// always a size_t 400 /// \param ElementType - the base element allocated type, 401 /// i.e. the allocated type after stripping all array types 402 virtual llvm::Value *InitializeArrayCookie(CodeGenFunction &CGF, 403 llvm::Value *NewPtr, 404 llvm::Value *NumElements, 405 const CXXNewExpr *expr, 406 QualType ElementType); 407 408 /// Reads the array cookie associated with the given pointer, 409 /// if it has one. 410 /// 411 /// \param Ptr - a pointer to the first element in the array 412 /// \param ElementType - the base element type of elements of the array 413 /// \param NumElements - an out parameter which will be initialized 414 /// with the number of elements allocated, or zero if there is no 415 /// cookie 416 /// \param AllocPtr - an out parameter which will be initialized 417 /// with a char* pointing to the address returned by the allocation 418 /// function 419 /// \param CookieSize - an out parameter which will be initialized 420 /// with the size of the cookie, or zero if there is no cookie 421 virtual void ReadArrayCookie(CodeGenFunction &CGF, llvm::Value *Ptr, 422 const CXXDeleteExpr *expr, 423 QualType ElementType, llvm::Value *&NumElements, 424 llvm::Value *&AllocPtr, CharUnits &CookieSize); 425 426 /// Return whether the given global decl needs a VTT parameter. 427 virtual bool NeedsVTTParameter(GlobalDecl GD); 428 429protected: 430 /// Returns the extra size required in order to store the array 431 /// cookie for the given type. Assumes that an array cookie is 432 /// required. 433 virtual CharUnits getArrayCookieSizeImpl(QualType elementType); 434 435 /// Reads the array cookie for an allocation which is known to have one. 436 /// This is called by the standard implementation of ReadArrayCookie. 437 /// 438 /// \param ptr - a pointer to the allocation made for an array, as a char* 439 /// \param cookieSize - the computed cookie size of an array 440 /// 441 /// Other parameters are as above. 442 /// 443 /// \return a size_t 444 virtual llvm::Value *readArrayCookieImpl(CodeGenFunction &IGF, 445 llvm::Value *ptr, 446 CharUnits cookieSize); 447 448public: 449 450 /*************************** Static local guards ****************************/ 451 452 /// Emits the guarded initializer and destructor setup for the given 453 /// variable, given that it couldn't be emitted as a constant. 454 /// If \p PerformInit is false, the initialization has been folded to a 455 /// constant and should not be performed. 456 /// 457 /// The variable may be: 458 /// - a static local variable 459 /// - a static data member of a class template instantiation 460 virtual void EmitGuardedInit(CodeGenFunction &CGF, const VarDecl &D, 461 llvm::GlobalVariable *DeclPtr, 462 bool PerformInit) = 0; 463 464 /// Emit code to force the execution of a destructor during global 465 /// teardown. The default implementation of this uses atexit. 466 /// 467 /// \param dtor - a function taking a single pointer argument 468 /// \param addr - a pointer to pass to the destructor function. 469 virtual void registerGlobalDtor(CodeGenFunction &CGF, const VarDecl &D, 470 llvm::Constant *dtor, llvm::Constant *addr); 471 472 /*************************** thread_local initialization ********************/ 473 474 /// Emits ABI-required functions necessary to initialize thread_local 475 /// variables in this translation unit. 476 /// 477 /// \param Decls The thread_local declarations in this translation unit. 478 /// \param InitFunc If this translation unit contains any non-constant 479 /// initialization or non-trivial destruction for thread_local 480 /// variables, a function to perform the initialization. Otherwise, 0. 481 virtual void EmitThreadLocalInitFuncs( 482 llvm::ArrayRef<std::pair<const VarDecl *, llvm::GlobalVariable *> > Decls, 483 llvm::Function *InitFunc); 484 485 /// Emit a reference to a non-local thread_local variable (including 486 /// triggering the initialization of all thread_local variables in its 487 /// translation unit). 488 virtual LValue EmitThreadLocalDeclRefExpr(CodeGenFunction &CGF, 489 const DeclRefExpr *DRE); 490}; 491 492// Create an instance of a C++ ABI class: 493 494/// Creates an Itanium-family ABI. 495CGCXXABI *CreateItaniumCXXABI(CodeGenModule &CGM); 496 497/// Creates a Microsoft-family ABI. 498CGCXXABI *CreateMicrosoftCXXABI(CodeGenModule &CGM); 499 500} 501} 502 503#endif 504