CGCXXABI.h revision 14110477887e3dc168ffc6c191e72d705051f99e
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 20namespace llvm { 21 class Constant; 22 class Type; 23 class Value; 24 25 template <class T> class SmallVectorImpl; 26} 27 28namespace clang { 29 class CastExpr; 30 class CXXConstructorDecl; 31 class CXXDestructorDecl; 32 class CXXMethodDecl; 33 class CXXRecordDecl; 34 class FieldDecl; 35 class MangleContext; 36 37namespace CodeGen { 38 class CodeGenFunction; 39 class CodeGenModule; 40 41/// Implements C++ ABI-specific code generation functions. 42class CGCXXABI { 43protected: 44 CodeGenModule &CGM; 45 llvm::OwningPtr<MangleContext> MangleCtx; 46 47 CGCXXABI(CodeGenModule &CGM) 48 : CGM(CGM), MangleCtx(CGM.getContext().createMangleContext()) {} 49 50protected: 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 74public: 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 const 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 *EmitMemberPointer(const FieldDecl *FD); 126 127 /// Emit a comparison between two member pointers. Returns an i1. 128 virtual llvm::Value * 129 EmitMemberPointerComparison(CodeGenFunction &CGF, 130 llvm::Value *L, 131 llvm::Value *R, 132 const MemberPointerType *MPT, 133 bool Inequality); 134 135 /// Determine if a member pointer is non-null. Returns an i1. 136 virtual llvm::Value * 137 EmitMemberPointerIsNotNull(CodeGenFunction &CGF, 138 llvm::Value *MemPtr, 139 const MemberPointerType *MPT); 140 141 /// Build the signature of the given constructor variant by adding 142 /// any required parameters. For convenience, ResTy has been 143 /// initialized to 'void', and ArgTys has been initialized with the 144 /// type of 'this' (although this may be changed by the ABI) and 145 /// will have the formal parameters added to it afterwards. 146 /// 147 /// If there are ever any ABIs where the implicit parameters are 148 /// intermixed with the formal parameters, we can address those 149 /// then. 150 virtual void BuildConstructorSignature(const CXXConstructorDecl *Ctor, 151 CXXCtorType T, 152 CanQualType &ResTy, 153 llvm::SmallVectorImpl<CanQualType> &ArgTys) = 0; 154 155 /// Build the signature of the given destructor variant by adding 156 /// any required parameters. For convenience, ResTy has been 157 /// initialized to 'void' and ArgTys has been initialized with the 158 /// type of 'this' (although this may be changed by the ABI). 159 virtual void BuildDestructorSignature(const CXXDestructorDecl *Dtor, 160 CXXDtorType T, 161 CanQualType &ResTy, 162 llvm::SmallVectorImpl<CanQualType> &ArgTys) = 0; 163 164 /// Build the ABI-specific portion of the parameter list for a 165 /// function. This generally involves a 'this' parameter and 166 /// possibly some extra data for constructors and destructors. 167 /// 168 /// ABIs may also choose to override the return type, which has been 169 /// initialized with the formal return type of the function. 170 virtual void BuildInstanceFunctionParams(CodeGenFunction &CGF, 171 QualType &ResTy, 172 FunctionArgList &Params) = 0; 173 174 /// Emit the ABI-specific prolog for the function. 175 virtual void EmitInstanceFunctionProlog(CodeGenFunction &CGF) = 0; 176 177 virtual void EmitReturnFromThunk(CodeGenFunction &CGF, 178 RValue RV, QualType ResultType); 179 180 /**************************** Array cookies ******************************/ 181 182 /// Returns the extra size required in order to store the array 183 /// cookie for the given type. May return 0 to indicate that no 184 /// array cookie is required. 185 /// 186 /// Several cases are filtered out before this method is called: 187 /// - non-array allocations never need a cookie 188 /// - calls to ::operator new(size_t, void*) never need a cookie 189 /// 190 /// \param ElementType - the allocated type of the expression, 191 /// i.e. the pointee type of the expression result type 192 virtual CharUnits GetArrayCookieSize(QualType ElementType); 193 194 /// Initialize the array cookie for the given allocation. 195 /// 196 /// \param NewPtr - a char* which is the presumed-non-null 197 /// return value of the allocation function 198 /// \param NumElements - the computed number of elements, 199 /// potentially collapsed from the multidimensional array case 200 /// \param ElementType - the base element allocated type, 201 /// i.e. the allocated type after stripping all array types 202 virtual llvm::Value *InitializeArrayCookie(CodeGenFunction &CGF, 203 llvm::Value *NewPtr, 204 llvm::Value *NumElements, 205 QualType ElementType); 206 207 /// Reads the array cookie associated with the given pointer, 208 /// if it has one. 209 /// 210 /// \param Ptr - a pointer to the first element in the array 211 /// \param ElementType - the base element type of elements of the array 212 /// \param NumElements - an out parameter which will be initialized 213 /// with the number of elements allocated, or zero if there is no 214 /// cookie 215 /// \param AllocPtr - an out parameter which will be initialized 216 /// with a char* pointing to the address returned by the allocation 217 /// function 218 /// \param CookieSize - an out parameter which will be initialized 219 /// with the size of the cookie, or zero if there is no cookie 220 virtual void ReadArrayCookie(CodeGenFunction &CGF, llvm::Value *Ptr, 221 QualType ElementType, llvm::Value *&NumElements, 222 llvm::Value *&AllocPtr, CharUnits &CookieSize); 223 224 /*************************** Static local guards ****************************/ 225 226 /// Emits the guarded initializer and destructor setup for the given 227 /// variable, given that it couldn't be emitted as a constant. 228 /// 229 /// The variable may be: 230 /// - a static local variable 231 /// - a static data member of a class template instantiation 232 virtual void EmitGuardedInit(CodeGenFunction &CGF, const VarDecl &D, 233 llvm::GlobalVariable *DeclPtr); 234 235}; 236 237/// Creates an instance of a C++ ABI class. 238CGCXXABI *CreateARMCXXABI(CodeGenModule &CGM); 239CGCXXABI *CreateItaniumCXXABI(CodeGenModule &CGM); 240CGCXXABI *CreateMicrosoftCXXABI(CodeGenModule &CGM); 241 242} 243} 244 245#endif 246