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 21 namespace llvm { 22 class Constant; 23 class Type; 24 class Value; 25 } 26 27 namespace clang { 28 class CastExpr; 29 class CXXConstructorDecl; 30 class CXXDestructorDecl; 31 class CXXMethodDecl; 32 class CXXRecordDecl; 33 class FieldDecl; 34 class MangleContext; 35 36 namespace CodeGen { 37 class CodeGenFunction; 38 class CodeGenModule; 39 40 /// \brief Implements C++ ABI-specific code generation functions. 41 class CGCXXABI { 42 protected: 43 CodeGenModule &CGM; 44 OwningPtr<MangleContext> MangleCtx; 45 46 CGCXXABI(CodeGenModule &CGM) 47 : CGM(CGM), MangleCtx(CGM.getContext().createMangleContext()) {} 48 49 protected: 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 91 public: 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); 190 191 protected: 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); 204 205 public: 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 constructor variants required by this ABI. 238 virtual void EmitCXXConstructors(const CXXConstructorDecl *D) = 0; 239 240 /// Build the signature of the given destructor variant by adding 241 /// any required parameters. For convenience, ArgTys has been initialized 242 /// with the type of 'this' and ResTy has been initialized with the type of 243 /// 'this' if HasThisReturn(GlobalDecl(Dtor, T)) is true or 'void' otherwise 244 /// (although both may be changed by the ABI). 245 virtual void BuildDestructorSignature(const CXXDestructorDecl *Dtor, 246 CXXDtorType T, 247 CanQualType &ResTy, 248 SmallVectorImpl<CanQualType> &ArgTys) = 0; 249 250 /// Returns true if the given destructor type should be emitted as a linkonce 251 /// delegating thunk, regardless of whether the dtor is defined in this TU or 252 /// not. 253 virtual bool useThunkForDtorVariant(const CXXDestructorDecl *Dtor, 254 CXXDtorType DT) const = 0; 255 256 /// Emit destructor variants required by this ABI. 257 virtual void EmitCXXDestructors(const CXXDestructorDecl *D) = 0; 258 259 /// Build the ABI-specific portion of the parameter list for a 260 /// function. This generally involves a 'this' parameter and 261 /// possibly some extra data for constructors and destructors. 262 /// 263 /// ABIs may also choose to override the return type, which has been 264 /// initialized with the type of 'this' if HasThisReturn(CGF.CurGD) is true or 265 /// the formal return type of the function otherwise. 266 virtual void BuildInstanceFunctionParams(CodeGenFunction &CGF, 267 QualType &ResTy, 268 FunctionArgList &Params) = 0; 269 270 /// Emit the ABI-specific prolog for the function. 271 virtual void EmitInstanceFunctionProlog(CodeGenFunction &CGF) = 0; 272 273 /// Emit the constructor call. Return the function that is called. 274 virtual void EmitConstructorCall(CodeGenFunction &CGF, 275 const CXXConstructorDecl *D, 276 CXXCtorType Type, 277 bool ForVirtualBase, bool Delegating, 278 llvm::Value *This, 279 CallExpr::const_arg_iterator ArgBeg, 280 CallExpr::const_arg_iterator ArgEnd) = 0; 281 282 /// Emit the ABI-specific virtual destructor call. 283 virtual void EmitVirtualDestructorCall(CodeGenFunction &CGF, 284 const CXXDestructorDecl *Dtor, 285 CXXDtorType DtorType, 286 SourceLocation CallLoc, 287 llvm::Value *This) = 0; 288 289 /// Emit any tables needed to implement virtual inheritance. For Itanium, 290 /// this emits virtual table tables. For the MSVC++ ABI, this emits virtual 291 /// base tables. 292 virtual void 293 EmitVirtualInheritanceTables(llvm::GlobalVariable::LinkageTypes Linkage, 294 const CXXRecordDecl *RD) = 0; 295 296 virtual void EmitReturnFromThunk(CodeGenFunction &CGF, 297 RValue RV, QualType ResultType); 298 299 /// Gets the pure virtual member call function. 300 virtual StringRef GetPureVirtualCallName() = 0; 301 302 /// Gets the deleted virtual member call name. 303 virtual StringRef GetDeletedVirtualCallName() = 0; 304 305 /**************************** Array cookies ******************************/ 306 307 /// Returns the extra size required in order to store the array 308 /// cookie for the given new-expression. May return 0 to indicate that no 309 /// array cookie is required. 310 /// 311 /// Several cases are filtered out before this method is called: 312 /// - non-array allocations never need a cookie 313 /// - calls to \::operator new(size_t, void*) never need a cookie 314 /// 315 /// \param expr - the new-expression being allocated. 316 virtual CharUnits GetArrayCookieSize(const CXXNewExpr *expr); 317 318 /// Initialize the array cookie for the given allocation. 319 /// 320 /// \param NewPtr - a char* which is the presumed-non-null 321 /// return value of the allocation function 322 /// \param NumElements - the computed number of elements, 323 /// potentially collapsed from the multidimensional array case; 324 /// always a size_t 325 /// \param ElementType - the base element allocated type, 326 /// i.e. the allocated type after stripping all array types 327 virtual llvm::Value *InitializeArrayCookie(CodeGenFunction &CGF, 328 llvm::Value *NewPtr, 329 llvm::Value *NumElements, 330 const CXXNewExpr *expr, 331 QualType ElementType); 332 333 /// Reads the array cookie associated with the given pointer, 334 /// if it has one. 335 /// 336 /// \param Ptr - a pointer to the first element in the array 337 /// \param ElementType - the base element type of elements of the array 338 /// \param NumElements - an out parameter which will be initialized 339 /// with the number of elements allocated, or zero if there is no 340 /// cookie 341 /// \param AllocPtr - an out parameter which will be initialized 342 /// with a char* pointing to the address returned by the allocation 343 /// function 344 /// \param CookieSize - an out parameter which will be initialized 345 /// with the size of the cookie, or zero if there is no cookie 346 virtual void ReadArrayCookie(CodeGenFunction &CGF, llvm::Value *Ptr, 347 const CXXDeleteExpr *expr, 348 QualType ElementType, llvm::Value *&NumElements, 349 llvm::Value *&AllocPtr, CharUnits &CookieSize); 350 351 /// Return whether the given global decl needs a VTT parameter. 352 virtual bool NeedsVTTParameter(GlobalDecl GD); 353 354 protected: 355 /// Returns the extra size required in order to store the array 356 /// cookie for the given type. Assumes that an array cookie is 357 /// required. 358 virtual CharUnits getArrayCookieSizeImpl(QualType elementType); 359 360 /// Reads the array cookie for an allocation which is known to have one. 361 /// This is called by the standard implementation of ReadArrayCookie. 362 /// 363 /// \param ptr - a pointer to the allocation made for an array, as a char* 364 /// \param cookieSize - the computed cookie size of an array 365 /// 366 /// Other parameters are as above. 367 /// 368 /// \return a size_t 369 virtual llvm::Value *readArrayCookieImpl(CodeGenFunction &IGF, 370 llvm::Value *ptr, 371 CharUnits cookieSize); 372 373 public: 374 375 /*************************** Static local guards ****************************/ 376 377 /// Emits the guarded initializer and destructor setup for the given 378 /// variable, given that it couldn't be emitted as a constant. 379 /// If \p PerformInit is false, the initialization has been folded to a 380 /// constant and should not be performed. 381 /// 382 /// The variable may be: 383 /// - a static local variable 384 /// - a static data member of a class template instantiation 385 virtual void EmitGuardedInit(CodeGenFunction &CGF, const VarDecl &D, 386 llvm::GlobalVariable *DeclPtr, bool PerformInit); 387 388 /// Emit code to force the execution of a destructor during global 389 /// teardown. The default implementation of this uses atexit. 390 /// 391 /// \param dtor - a function taking a single pointer argument 392 /// \param addr - a pointer to pass to the destructor function. 393 virtual void registerGlobalDtor(CodeGenFunction &CGF, const VarDecl &D, 394 llvm::Constant *dtor, llvm::Constant *addr); 395 396 /*************************** thread_local initialization ********************/ 397 398 /// Emits ABI-required functions necessary to initialize thread_local 399 /// variables in this translation unit. 400 /// 401 /// \param Decls The thread_local declarations in this translation unit. 402 /// \param InitFunc If this translation unit contains any non-constant 403 /// initialization or non-trivial destruction for thread_local 404 /// variables, a function to perform the initialization. Otherwise, 0. 405 virtual void EmitThreadLocalInitFuncs( 406 llvm::ArrayRef<std::pair<const VarDecl *, llvm::GlobalVariable *> > Decls, 407 llvm::Function *InitFunc); 408 409 /// Emit a reference to a non-local thread_local variable (including 410 /// triggering the initialization of all thread_local variables in its 411 /// translation unit). 412 virtual LValue EmitThreadLocalDeclRefExpr(CodeGenFunction &CGF, 413 const DeclRefExpr *DRE); 414 }; 415 416 // Create an instance of a C++ ABI class: 417 418 /// Creates an Itanium-family ABI. 419 CGCXXABI *CreateItaniumCXXABI(CodeGenModule &CGM); 420 421 /// Creates a Microsoft-family ABI. 422 CGCXXABI *CreateMicrosoftCXXABI(CodeGenModule &CGM); 423 424 } 425 } 426 427 #endif 428
