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 "clang/Basic/LLVM.h" 19 20 #include "CodeGenFunction.h" 21 22 namespace llvm { 23 class Constant; 24 class Type; 25 class Value; 26 } 27 28 namespace clang { 29 class CastExpr; 30 class CXXConstructorDecl; 31 class CXXDestructorDecl; 32 class CXXMethodDecl; 33 class CXXRecordDecl; 34 class FieldDecl; 35 class MangleContext; 36 37 namespace CodeGen { 38 class CodeGenFunction; 39 class CodeGenModule; 40 41 /// Implements C++ ABI-specific code generation functions. 42 class CGCXXABI { 43 protected: 44 CodeGenModule &CGM; 45 llvm::OwningPtr<MangleContext> MangleCtx; 46 47 CGCXXABI(CodeGenModule &CGM) 48 : CGM(CGM), MangleCtx(CGM.getContext().createMangleContext()) {} 49 50 protected: 51 ImplicitParamDecl *&getThisDecl(CodeGenFunction &CGF) { 52 return CGF.CXXThisDecl; 53 } 54 llvm::Value *&getThisValue(CodeGenFunction &CGF) { 55 return CGF.CXXThisValue; 56 } 57 58 ImplicitParamDecl *&getVTTDecl(CodeGenFunction &CGF) { 59 return CGF.CXXVTTDecl; 60 } 61 llvm::Value *&getVTTValue(CodeGenFunction &CGF) { 62 return CGF.CXXVTTValue; 63 } 64 65 /// Build a parameter variable suitable for 'this'. 66 void BuildThisParam(CodeGenFunction &CGF, FunctionArgList &Params); 67 68 /// Perform prolog initialization of the parameter variable suitable 69 /// for 'this' emitted by BuildThisParam. 70 void EmitThisParam(CodeGenFunction &CGF); 71 72 ASTContext &getContext() const { return CGM.getContext(); } 73 74 public: 75 76 virtual ~CGCXXABI(); 77 78 /// Gets the mangle context. 79 MangleContext &getMangleContext() { 80 return *MangleCtx; 81 } 82 83 /// Find the LLVM type used to represent the given member pointer 84 /// type. 85 virtual llvm::Type * 86 ConvertMemberPointerType(const MemberPointerType *MPT); 87 88 /// Load a member function from an object and a member function 89 /// pointer. Apply the this-adjustment and set 'This' to the 90 /// adjusted value. 91 virtual llvm::Value * 92 EmitLoadOfMemberFunctionPointer(CodeGenFunction &CGF, 93 llvm::Value *&This, 94 llvm::Value *MemPtr, 95 const MemberPointerType *MPT); 96 97 /// Calculate an l-value from an object and a data member pointer. 98 virtual llvm::Value *EmitMemberDataPointerAddress(CodeGenFunction &CGF, 99 llvm::Value *Base, 100 llvm::Value *MemPtr, 101 const MemberPointerType *MPT); 102 103 /// Perform a derived-to-base or base-to-derived member pointer 104 /// conversion. 105 virtual llvm::Value *EmitMemberPointerConversion(CodeGenFunction &CGF, 106 const CastExpr *E, 107 llvm::Value *Src); 108 109 /// Perform a derived-to-base or base-to-derived member pointer 110 /// conversion on a constant member pointer. 111 virtual llvm::Constant *EmitMemberPointerConversion(llvm::Constant *C, 112 const CastExpr *E); 113 114 /// Return true if the given member pointer can be zero-initialized 115 /// (in the C++ sense) with an LLVM zeroinitializer. 116 virtual bool isZeroInitializable(const MemberPointerType *MPT); 117 118 /// Create a null member pointer of the given type. 119 virtual llvm::Constant *EmitNullMemberPointer(const MemberPointerType *MPT); 120 121 /// Create a member pointer for the given method. 122 virtual llvm::Constant *EmitMemberPointer(const CXXMethodDecl *MD); 123 124 /// Create a member pointer for the given field. 125 virtual llvm::Constant *EmitMemberDataPointer(const MemberPointerType *MPT, 126 CharUnits offset); 127 128 /// Emit a comparison between two member pointers. Returns an i1. 129 virtual llvm::Value * 130 EmitMemberPointerComparison(CodeGenFunction &CGF, 131 llvm::Value *L, 132 llvm::Value *R, 133 const MemberPointerType *MPT, 134 bool Inequality); 135 136 /// Determine if a member pointer is non-null. Returns an i1. 137 virtual llvm::Value * 138 EmitMemberPointerIsNotNull(CodeGenFunction &CGF, 139 llvm::Value *MemPtr, 140 const MemberPointerType *MPT); 141 142 /// Build the signature of the given constructor variant by adding 143 /// any required parameters. For convenience, ResTy has been 144 /// initialized to 'void', and ArgTys has been initialized with the 145 /// type of 'this' (although this may be changed by the ABI) and 146 /// will have the formal parameters added to it afterwards. 147 /// 148 /// If there are ever any ABIs where the implicit parameters are 149 /// intermixed with the formal parameters, we can address those 150 /// then. 151 virtual void BuildConstructorSignature(const CXXConstructorDecl *Ctor, 152 CXXCtorType T, 153 CanQualType &ResTy, 154 SmallVectorImpl<CanQualType> &ArgTys) = 0; 155 156 /// Build the signature of the given destructor variant by adding 157 /// any required parameters. For convenience, ResTy has been 158 /// initialized to 'void' and ArgTys has been initialized with the 159 /// type of 'this' (although this may be changed by the ABI). 160 virtual void BuildDestructorSignature(const CXXDestructorDecl *Dtor, 161 CXXDtorType T, 162 CanQualType &ResTy, 163 SmallVectorImpl<CanQualType> &ArgTys) = 0; 164 165 /// Build the ABI-specific portion of the parameter list for a 166 /// function. This generally involves a 'this' parameter and 167 /// possibly some extra data for constructors and destructors. 168 /// 169 /// ABIs may also choose to override the return type, which has been 170 /// initialized with the formal return type of the function. 171 virtual void BuildInstanceFunctionParams(CodeGenFunction &CGF, 172 QualType &ResTy, 173 FunctionArgList &Params) = 0; 174 175 /// Emit the ABI-specific prolog for the function. 176 virtual void EmitInstanceFunctionProlog(CodeGenFunction &CGF) = 0; 177 178 virtual void EmitReturnFromThunk(CodeGenFunction &CGF, 179 RValue RV, QualType ResultType); 180 181 /**************************** Array cookies ******************************/ 182 183 /// Returns the extra size required in order to store the array 184 /// cookie for the given type. May return 0 to indicate that no 185 /// array cookie is required. 186 /// 187 /// Several cases are filtered out before this method is called: 188 /// - non-array allocations never need a cookie 189 /// - calls to ::operator new(size_t, void*) never need a cookie 190 /// 191 /// \param ElementType - the allocated type of the expression, 192 /// i.e. the pointee type of the expression result type 193 virtual CharUnits GetArrayCookieSize(const CXXNewExpr *expr); 194 195 /// Initialize the array cookie for the given allocation. 196 /// 197 /// \param NewPtr - a char* which is the presumed-non-null 198 /// return value of the allocation function 199 /// \param NumElements - the computed number of elements, 200 /// potentially collapsed from the multidimensional array case 201 /// \param ElementType - the base element allocated type, 202 /// i.e. the allocated type after stripping all array types 203 virtual llvm::Value *InitializeArrayCookie(CodeGenFunction &CGF, 204 llvm::Value *NewPtr, 205 llvm::Value *NumElements, 206 const CXXNewExpr *expr, 207 QualType ElementType); 208 209 /// Reads the array cookie associated with the given pointer, 210 /// if it has one. 211 /// 212 /// \param Ptr - a pointer to the first element in the array 213 /// \param ElementType - the base element type of elements of the array 214 /// \param NumElements - an out parameter which will be initialized 215 /// with the number of elements allocated, or zero if there is no 216 /// cookie 217 /// \param AllocPtr - an out parameter which will be initialized 218 /// with a char* pointing to the address returned by the allocation 219 /// function 220 /// \param CookieSize - an out parameter which will be initialized 221 /// with the size of the cookie, or zero if there is no cookie 222 virtual void ReadArrayCookie(CodeGenFunction &CGF, llvm::Value *Ptr, 223 const CXXDeleteExpr *expr, 224 QualType ElementType, llvm::Value *&NumElements, 225 llvm::Value *&AllocPtr, CharUnits &CookieSize); 226 227 /*************************** Static local guards ****************************/ 228 229 /// Emits the guarded initializer and destructor setup for the given 230 /// variable, given that it couldn't be emitted as a constant. 231 /// 232 /// The variable may be: 233 /// - a static local variable 234 /// - a static data member of a class template instantiation 235 virtual void EmitGuardedInit(CodeGenFunction &CGF, const VarDecl &D, 236 llvm::GlobalVariable *DeclPtr); 237 238 }; 239 240 /// Creates an instance of a C++ ABI class. 241 CGCXXABI *CreateARMCXXABI(CodeGenModule &CGM); 242 CGCXXABI *CreateItaniumCXXABI(CodeGenModule &CGM); 243 CGCXXABI *CreateMicrosoftCXXABI(CodeGenModule &CGM); 244 245 } 246 } 247 248 #endif 249
