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 // FIXME: Every place that calls getVTT{Decl,Value} is something 58 // that needs to be abstracted properly. 59 ImplicitParamDecl *&getVTTDecl(CodeGenFunction &CGF) { 60 return CGF.CXXStructorImplicitParamDecl; 61 } 62 llvm::Value *&getVTTValue(CodeGenFunction &CGF) { 63 return CGF.CXXStructorImplicitParamValue; 64 } 65 66 ImplicitParamDecl *&getStructorImplicitParamDecl(CodeGenFunction &CGF) { 67 return CGF.CXXStructorImplicitParamDecl; 68 } 69 llvm::Value *&getStructorImplicitParamValue(CodeGenFunction &CGF) { 70 return CGF.CXXStructorImplicitParamValue; 71 } 72 73 /// Build a parameter variable suitable for 'this'. 74 void BuildThisParam(CodeGenFunction &CGF, FunctionArgList &Params); 75 76 /// Perform prolog initialization of the parameter variable suitable 77 /// for 'this' emitted by BuildThisParam. 78 void EmitThisParam(CodeGenFunction &CGF); 79 80 ASTContext &getContext() const { return CGM.getContext(); } 81 82 virtual bool requiresArrayCookie(const CXXDeleteExpr *E, QualType eltType); 83 virtual bool requiresArrayCookie(const CXXNewExpr *E); 84 85 public: 86 87 virtual ~CGCXXABI(); 88 89 /// Gets the mangle context. 90 MangleContext &getMangleContext() { 91 return *MangleCtx; 92 } 93 94 /// Find the LLVM type used to represent the given member pointer 95 /// type. 96 virtual llvm::Type * 97 ConvertMemberPointerType(const MemberPointerType *MPT); 98 99 /// Load a member function from an object and a member function 100 /// pointer. Apply the this-adjustment and set 'This' to the 101 /// adjusted value. 102 virtual llvm::Value * 103 EmitLoadOfMemberFunctionPointer(CodeGenFunction &CGF, 104 llvm::Value *&This, 105 llvm::Value *MemPtr, 106 const MemberPointerType *MPT); 107 108 /// Calculate an l-value from an object and a data member pointer. 109 virtual llvm::Value *EmitMemberDataPointerAddress(CodeGenFunction &CGF, 110 llvm::Value *Base, 111 llvm::Value *MemPtr, 112 const MemberPointerType *MPT); 113 114 /// Perform a derived-to-base, base-to-derived, or bitcast member 115 /// pointer conversion. 116 virtual llvm::Value *EmitMemberPointerConversion(CodeGenFunction &CGF, 117 const CastExpr *E, 118 llvm::Value *Src); 119 120 /// Perform a derived-to-base, base-to-derived, or bitcast member 121 /// pointer conversion on a constant value. 122 virtual llvm::Constant *EmitMemberPointerConversion(const CastExpr *E, 123 llvm::Constant *Src); 124 125 /// Return true if the given member pointer can be zero-initialized 126 /// (in the C++ sense) with an LLVM zeroinitializer. 127 virtual bool isZeroInitializable(const MemberPointerType *MPT); 128 129 /// Create a null member pointer of the given type. 130 virtual llvm::Constant *EmitNullMemberPointer(const MemberPointerType *MPT); 131 132 /// Create a member pointer for the given method. 133 virtual llvm::Constant *EmitMemberPointer(const CXXMethodDecl *MD); 134 135 /// Create a member pointer for the given field. 136 virtual llvm::Constant *EmitMemberDataPointer(const MemberPointerType *MPT, 137 CharUnits offset); 138 139 /// Create a member pointer for the given member pointer constant. 140 virtual llvm::Constant *EmitMemberPointer(const APValue &MP, QualType MPT); 141 142 /// Emit a comparison between two member pointers. Returns an i1. 143 virtual llvm::Value * 144 EmitMemberPointerComparison(CodeGenFunction &CGF, 145 llvm::Value *L, 146 llvm::Value *R, 147 const MemberPointerType *MPT, 148 bool Inequality); 149 150 /// Determine if a member pointer is non-null. Returns an i1. 151 virtual llvm::Value * 152 EmitMemberPointerIsNotNull(CodeGenFunction &CGF, 153 llvm::Value *MemPtr, 154 const MemberPointerType *MPT); 155 156 protected: 157 /// A utility method for computing the offset required for the given 158 /// base-to-derived or derived-to-base member-pointer conversion. 159 /// Does not handle virtual conversions (in case we ever fully 160 /// support an ABI that allows this). Returns null if no adjustment 161 /// is required. 162 llvm::Constant *getMemberPointerAdjustment(const CastExpr *E); 163 164 public: 165 /// Adjust the given non-null pointer to an object of polymorphic 166 /// type to point to the complete object. 167 /// 168 /// The IR type of the result should be a pointer but is otherwise 169 /// irrelevant. 170 virtual llvm::Value *adjustToCompleteObject(CodeGenFunction &CGF, 171 llvm::Value *ptr, 172 QualType type) = 0; 173 174 /// Build the signature of the given constructor variant by adding 175 /// any required parameters. For convenience, ResTy has been 176 /// initialized to 'void', and ArgTys has been initialized with the 177 /// type of 'this' (although this may be changed by the ABI) and 178 /// will have the formal parameters added to it afterwards. 179 /// 180 /// If there are ever any ABIs where the implicit parameters are 181 /// intermixed with the formal parameters, we can address those 182 /// then. 183 virtual void BuildConstructorSignature(const CXXConstructorDecl *Ctor, 184 CXXCtorType T, 185 CanQualType &ResTy, 186 SmallVectorImpl<CanQualType> &ArgTys) = 0; 187 188 virtual llvm::BasicBlock *EmitCtorCompleteObjectHandler(CodeGenFunction &CGF); 189 190 /// Build the signature of the given destructor variant by adding 191 /// any required parameters. For convenience, ResTy has been 192 /// initialized to 'void' and ArgTys has been initialized with the 193 /// type of 'this' (although this may be changed by the ABI). 194 virtual void BuildDestructorSignature(const CXXDestructorDecl *Dtor, 195 CXXDtorType T, 196 CanQualType &ResTy, 197 SmallVectorImpl<CanQualType> &ArgTys) = 0; 198 199 /// Build the ABI-specific portion of the parameter list for a 200 /// function. This generally involves a 'this' parameter and 201 /// possibly some extra data for constructors and destructors. 202 /// 203 /// ABIs may also choose to override the return type, which has been 204 /// initialized with the formal return type of the function. 205 virtual void BuildInstanceFunctionParams(CodeGenFunction &CGF, 206 QualType &ResTy, 207 FunctionArgList &Params) = 0; 208 209 /// Emit the ABI-specific prolog for the function. 210 virtual void EmitInstanceFunctionProlog(CodeGenFunction &CGF) = 0; 211 212 virtual void EmitConstructorCall(CodeGenFunction &CGF, 213 const CXXConstructorDecl *D, 214 CXXCtorType Type, bool ForVirtualBase, 215 bool Delegating, 216 llvm::Value *This, 217 CallExpr::const_arg_iterator ArgBeg, 218 CallExpr::const_arg_iterator ArgEnd) = 0; 219 220 /// Emit the ABI-specific virtual destructor call. 221 virtual RValue EmitVirtualDestructorCall(CodeGenFunction &CGF, 222 const CXXDestructorDecl *Dtor, 223 CXXDtorType DtorType, 224 SourceLocation CallLoc, 225 ReturnValueSlot ReturnValue, 226 llvm::Value *This) = 0; 227 228 virtual void EmitReturnFromThunk(CodeGenFunction &CGF, 229 RValue RV, QualType ResultType); 230 231 /// Gets the pure virtual member call function. 232 virtual StringRef GetPureVirtualCallName() = 0; 233 234 /// Gets the deleted virtual member call name. 235 virtual StringRef GetDeletedVirtualCallName() = 0; 236 237 /**************************** Array cookies ******************************/ 238 239 /// Returns the extra size required in order to store the array 240 /// cookie for the given new-expression. May return 0 to indicate that no 241 /// array cookie is required. 242 /// 243 /// Several cases are filtered out before this method is called: 244 /// - non-array allocations never need a cookie 245 /// - calls to \::operator new(size_t, void*) never need a cookie 246 /// 247 /// \param expr - the new-expression being allocated. 248 virtual CharUnits GetArrayCookieSize(const CXXNewExpr *expr); 249 250 /// Initialize the array cookie for the given allocation. 251 /// 252 /// \param NewPtr - a char* which is the presumed-non-null 253 /// return value of the allocation function 254 /// \param NumElements - the computed number of elements, 255 /// potentially collapsed from the multidimensional array case; 256 /// always a size_t 257 /// \param ElementType - the base element allocated type, 258 /// i.e. the allocated type after stripping all array types 259 virtual llvm::Value *InitializeArrayCookie(CodeGenFunction &CGF, 260 llvm::Value *NewPtr, 261 llvm::Value *NumElements, 262 const CXXNewExpr *expr, 263 QualType ElementType); 264 265 /// Reads the array cookie associated with the given pointer, 266 /// if it has one. 267 /// 268 /// \param Ptr - a pointer to the first element in the array 269 /// \param ElementType - the base element type of elements of the array 270 /// \param NumElements - an out parameter which will be initialized 271 /// with the number of elements allocated, or zero if there is no 272 /// cookie 273 /// \param AllocPtr - an out parameter which will be initialized 274 /// with a char* pointing to the address returned by the allocation 275 /// function 276 /// \param CookieSize - an out parameter which will be initialized 277 /// with the size of the cookie, or zero if there is no cookie 278 virtual void ReadArrayCookie(CodeGenFunction &CGF, llvm::Value *Ptr, 279 const CXXDeleteExpr *expr, 280 QualType ElementType, llvm::Value *&NumElements, 281 llvm::Value *&AllocPtr, CharUnits &CookieSize); 282 283 protected: 284 /// Returns the extra size required in order to store the array 285 /// cookie for the given type. Assumes that an array cookie is 286 /// required. 287 virtual CharUnits getArrayCookieSizeImpl(QualType elementType); 288 289 /// Reads the array cookie for an allocation which is known to have one. 290 /// This is called by the standard implementation of ReadArrayCookie. 291 /// 292 /// \param ptr - a pointer to the allocation made for an array, as a char* 293 /// \param cookieSize - the computed cookie size of an array 294 /// 295 /// Other parameters are as above. 296 /// 297 /// \return a size_t 298 virtual llvm::Value *readArrayCookieImpl(CodeGenFunction &IGF, 299 llvm::Value *ptr, 300 CharUnits cookieSize); 301 302 public: 303 304 /*************************** Static local guards ****************************/ 305 306 /// Emits the guarded initializer and destructor setup for the given 307 /// variable, given that it couldn't be emitted as a constant. 308 /// If \p PerformInit is false, the initialization has been folded to a 309 /// constant and should not be performed. 310 /// 311 /// The variable may be: 312 /// - a static local variable 313 /// - a static data member of a class template instantiation 314 virtual void EmitGuardedInit(CodeGenFunction &CGF, const VarDecl &D, 315 llvm::GlobalVariable *DeclPtr, bool PerformInit); 316 317 /// Emit code to force the execution of a destructor during global 318 /// teardown. The default implementation of this uses atexit. 319 /// 320 /// \param dtor - a function taking a single pointer argument 321 /// \param addr - a pointer to pass to the destructor function. 322 virtual void registerGlobalDtor(CodeGenFunction &CGF, llvm::Constant *dtor, 323 llvm::Constant *addr); 324 }; 325 326 // Create an instance of a C++ ABI class: 327 328 /// Creates an Itanium-family ABI. 329 CGCXXABI *CreateItaniumCXXABI(CodeGenModule &CGM); 330 331 /// Creates a Microsoft-family ABI. 332 CGCXXABI *CreateMicrosoftCXXABI(CodeGenModule &CGM); 333 334 } 335 } 336 337 #endif 338
