CGCXXABI.h revision b80a16eadd0dacabfc1c32412e243ccb99dd664d
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 instance method is one of the 101 /// kinds that the ABI says returns 'this'. 102 virtual bool HasThisReturn(GlobalDecl GD) const { return false; } 103 104 /// Returns true if the given record type should be returned indirectly. 105 virtual bool isReturnTypeIndirect(const CXXRecordDecl *RD) const = 0; 106 107 /// Specify how one should pass an argument of a record type. 108 enum RecordArgABI { 109 /// Pass it using the normal C aggregate rules for the ABI, potentially 110 /// introducing extra copies and passing some or all of it in registers. 111 RAA_Default = 0, 112 113 /// Pass it on the stack using its defined layout. The argument must be 114 /// evaluated directly into the correct stack position in the arguments area, 115 /// and the call machinery must not move it or introduce extra copies. 116 RAA_DirectInMemory, 117 118 /// Pass it as a pointer to temporary memory. 119 RAA_Indirect 120 }; 121 122 /// Returns how an argument of the given record type should be passed. 123 virtual RecordArgABI getRecordArgABI(const CXXRecordDecl *RD) const = 0; 124 125 /// Find the LLVM type used to represent the given member pointer 126 /// type. 127 virtual llvm::Type * 128 ConvertMemberPointerType(const MemberPointerType *MPT); 129 130 /// Load a member function from an object and a member function 131 /// pointer. Apply the this-adjustment and set 'This' to the 132 /// adjusted value. 133 virtual llvm::Value * 134 EmitLoadOfMemberFunctionPointer(CodeGenFunction &CGF, 135 llvm::Value *&This, 136 llvm::Value *MemPtr, 137 const MemberPointerType *MPT); 138 139 /// Calculate an l-value from an object and a data member pointer. 140 virtual llvm::Value *EmitMemberDataPointerAddress(CodeGenFunction &CGF, 141 llvm::Value *Base, 142 llvm::Value *MemPtr, 143 const MemberPointerType *MPT); 144 145 /// Perform a derived-to-base, base-to-derived, or bitcast member 146 /// pointer conversion. 147 virtual llvm::Value *EmitMemberPointerConversion(CodeGenFunction &CGF, 148 const CastExpr *E, 149 llvm::Value *Src); 150 151 /// Perform a derived-to-base, base-to-derived, or bitcast member 152 /// pointer conversion on a constant value. 153 virtual llvm::Constant *EmitMemberPointerConversion(const CastExpr *E, 154 llvm::Constant *Src); 155 156 /// Return true if the given member pointer can be zero-initialized 157 /// (in the C++ sense) with an LLVM zeroinitializer. 158 virtual bool isZeroInitializable(const MemberPointerType *MPT); 159 160 /// Create a null member pointer of the given type. 161 virtual llvm::Constant *EmitNullMemberPointer(const MemberPointerType *MPT); 162 163 /// Create a member pointer for the given method. 164 virtual llvm::Constant *EmitMemberPointer(const CXXMethodDecl *MD); 165 166 /// Create a member pointer for the given field. 167 virtual llvm::Constant *EmitMemberDataPointer(const MemberPointerType *MPT, 168 CharUnits offset); 169 170 /// Create a member pointer for the given member pointer constant. 171 virtual llvm::Constant *EmitMemberPointer(const APValue &MP, QualType MPT); 172 173 /// Emit a comparison between two member pointers. Returns an i1. 174 virtual llvm::Value * 175 EmitMemberPointerComparison(CodeGenFunction &CGF, 176 llvm::Value *L, 177 llvm::Value *R, 178 const MemberPointerType *MPT, 179 bool Inequality); 180 181 /// Determine if a member pointer is non-null. Returns an i1. 182 virtual llvm::Value * 183 EmitMemberPointerIsNotNull(CodeGenFunction &CGF, 184 llvm::Value *MemPtr, 185 const MemberPointerType *MPT); 186 187protected: 188 /// A utility method for computing the offset required for the given 189 /// base-to-derived or derived-to-base member-pointer conversion. 190 /// Does not handle virtual conversions (in case we ever fully 191 /// support an ABI that allows this). Returns null if no adjustment 192 /// is required. 193 llvm::Constant *getMemberPointerAdjustment(const CastExpr *E); 194 195public: 196 /// Adjust the given non-null pointer to an object of polymorphic 197 /// type to point to the complete object. 198 /// 199 /// The IR type of the result should be a pointer but is otherwise 200 /// irrelevant. 201 virtual llvm::Value *adjustToCompleteObject(CodeGenFunction &CGF, 202 llvm::Value *ptr, 203 QualType type) = 0; 204 205 /// Build the signature of the given constructor variant by adding 206 /// any required parameters. For convenience, ResTy has been 207 /// initialized to 'void', and ArgTys has been initialized with the 208 /// type of 'this' (although this may be changed by the ABI) and 209 /// will have the formal parameters added to it afterwards. 210 /// 211 /// If there are ever any ABIs where the implicit parameters are 212 /// intermixed with the formal parameters, we can address those 213 /// then. 214 virtual void BuildConstructorSignature(const CXXConstructorDecl *Ctor, 215 CXXCtorType T, 216 CanQualType &ResTy, 217 SmallVectorImpl<CanQualType> &ArgTys) = 0; 218 219 virtual llvm::BasicBlock *EmitCtorCompleteObjectHandler(CodeGenFunction &CGF); 220 221 /// Build the signature of the given destructor variant by adding 222 /// any required parameters. For convenience, ResTy has been 223 /// initialized to 'void' and ArgTys has been initialized with the 224 /// type of 'this' (although this may be changed by the ABI). 225 virtual void BuildDestructorSignature(const CXXDestructorDecl *Dtor, 226 CXXDtorType T, 227 CanQualType &ResTy, 228 SmallVectorImpl<CanQualType> &ArgTys) = 0; 229 230 /// Build the ABI-specific portion of the parameter list for a 231 /// function. This generally involves a 'this' parameter and 232 /// possibly some extra data for constructors and destructors. 233 /// 234 /// ABIs may also choose to override the return type, which has been 235 /// initialized with the formal return type of the function. 236 virtual void BuildInstanceFunctionParams(CodeGenFunction &CGF, 237 QualType &ResTy, 238 FunctionArgList &Params) = 0; 239 240 /// Emit the ABI-specific prolog for the function. 241 virtual void EmitInstanceFunctionProlog(CodeGenFunction &CGF) = 0; 242 243 /// Emit the constructor call. Return the function that is called. 244 virtual llvm::Value *EmitConstructorCall(CodeGenFunction &CGF, 245 const CXXConstructorDecl *D, 246 CXXCtorType Type, bool ForVirtualBase, 247 bool Delegating, 248 llvm::Value *This, 249 CallExpr::const_arg_iterator ArgBeg, 250 CallExpr::const_arg_iterator ArgEnd) = 0; 251 252 /// Emit the ABI-specific virtual destructor call. 253 virtual RValue EmitVirtualDestructorCall(CodeGenFunction &CGF, 254 const CXXDestructorDecl *Dtor, 255 CXXDtorType DtorType, 256 SourceLocation CallLoc, 257 ReturnValueSlot ReturnValue, 258 llvm::Value *This) = 0; 259 260 virtual void EmitReturnFromThunk(CodeGenFunction &CGF, 261 RValue RV, QualType ResultType); 262 263 /// Gets the pure virtual member call function. 264 virtual StringRef GetPureVirtualCallName() = 0; 265 266 /// Gets the deleted virtual member call name. 267 virtual StringRef GetDeletedVirtualCallName() = 0; 268 269 /**************************** Array cookies ******************************/ 270 271 /// Returns the extra size required in order to store the array 272 /// cookie for the given new-expression. May return 0 to indicate that no 273 /// array cookie is required. 274 /// 275 /// Several cases are filtered out before this method is called: 276 /// - non-array allocations never need a cookie 277 /// - calls to \::operator new(size_t, void*) never need a cookie 278 /// 279 /// \param expr - the new-expression being allocated. 280 virtual CharUnits GetArrayCookieSize(const CXXNewExpr *expr); 281 282 /// Initialize the array cookie for the given allocation. 283 /// 284 /// \param NewPtr - a char* which is the presumed-non-null 285 /// return value of the allocation function 286 /// \param NumElements - the computed number of elements, 287 /// potentially collapsed from the multidimensional array case; 288 /// always a size_t 289 /// \param ElementType - the base element allocated type, 290 /// i.e. the allocated type after stripping all array types 291 virtual llvm::Value *InitializeArrayCookie(CodeGenFunction &CGF, 292 llvm::Value *NewPtr, 293 llvm::Value *NumElements, 294 const CXXNewExpr *expr, 295 QualType ElementType); 296 297 /// Reads the array cookie associated with the given pointer, 298 /// if it has one. 299 /// 300 /// \param Ptr - a pointer to the first element in the array 301 /// \param ElementType - the base element type of elements of the array 302 /// \param NumElements - an out parameter which will be initialized 303 /// with the number of elements allocated, or zero if there is no 304 /// cookie 305 /// \param AllocPtr - an out parameter which will be initialized 306 /// with a char* pointing to the address returned by the allocation 307 /// function 308 /// \param CookieSize - an out parameter which will be initialized 309 /// with the size of the cookie, or zero if there is no cookie 310 virtual void ReadArrayCookie(CodeGenFunction &CGF, llvm::Value *Ptr, 311 const CXXDeleteExpr *expr, 312 QualType ElementType, llvm::Value *&NumElements, 313 llvm::Value *&AllocPtr, CharUnits &CookieSize); 314 315protected: 316 /// Returns the extra size required in order to store the array 317 /// cookie for the given type. Assumes that an array cookie is 318 /// required. 319 virtual CharUnits getArrayCookieSizeImpl(QualType elementType); 320 321 /// Reads the array cookie for an allocation which is known to have one. 322 /// This is called by the standard implementation of ReadArrayCookie. 323 /// 324 /// \param ptr - a pointer to the allocation made for an array, as a char* 325 /// \param cookieSize - the computed cookie size of an array 326 /// 327 /// Other parameters are as above. 328 /// 329 /// \return a size_t 330 virtual llvm::Value *readArrayCookieImpl(CodeGenFunction &IGF, 331 llvm::Value *ptr, 332 CharUnits cookieSize); 333 334public: 335 336 /*************************** Static local guards ****************************/ 337 338 /// Emits the guarded initializer and destructor setup for the given 339 /// variable, given that it couldn't be emitted as a constant. 340 /// If \p PerformInit is false, the initialization has been folded to a 341 /// constant and should not be performed. 342 /// 343 /// The variable may be: 344 /// - a static local variable 345 /// - a static data member of a class template instantiation 346 virtual void EmitGuardedInit(CodeGenFunction &CGF, const VarDecl &D, 347 llvm::GlobalVariable *DeclPtr, bool PerformInit); 348 349 /// Emit code to force the execution of a destructor during global 350 /// teardown. The default implementation of this uses atexit. 351 /// 352 /// \param dtor - a function taking a single pointer argument 353 /// \param addr - a pointer to pass to the destructor function. 354 virtual void registerGlobalDtor(CodeGenFunction &CGF, const VarDecl &D, 355 llvm::Constant *dtor, llvm::Constant *addr); 356 357 /*************************** thread_local initialization ********************/ 358 359 /// Emits ABI-required functions necessary to initialize thread_local 360 /// variables in this translation unit. 361 /// 362 /// \param Decls The thread_local declarations in this translation unit. 363 /// \param InitFunc If this translation unit contains any non-constant 364 /// initialization or non-trivial destruction for thread_local 365 /// variables, a function to perform the initialization. Otherwise, 0. 366 virtual void EmitThreadLocalInitFuncs( 367 llvm::ArrayRef<std::pair<const VarDecl *, llvm::GlobalVariable *> > Decls, 368 llvm::Function *InitFunc); 369 370 /// Emit a reference to a non-local thread_local variable (including 371 /// triggering the initialization of all thread_local variables in its 372 /// translation unit). 373 virtual LValue EmitThreadLocalDeclRefExpr(CodeGenFunction &CGF, 374 const DeclRefExpr *DRE); 375}; 376 377// Create an instance of a C++ ABI class: 378 379/// Creates an Itanium-family ABI. 380CGCXXABI *CreateItaniumCXXABI(CodeGenModule &CGM); 381 382/// Creates a Microsoft-family ABI. 383CGCXXABI *CreateMicrosoftCXXABI(CodeGenModule &CGM); 384 385} 386} 387 388#endif 389