1 //===--- RecordLayout.h - Layout information for a struct/union -*- 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 file defines the RecordLayout interface. 11 // 12 //===----------------------------------------------------------------------===// 13 14 #ifndef LLVM_CLANG_AST_LAYOUTINFO_H 15 #define LLVM_CLANG_AST_LAYOUTINFO_H 16 17 #include "clang/AST/CharUnits.h" 18 #include "clang/AST/DeclCXX.h" 19 #include "llvm/ADT/DenseMap.h" 20 21 namespace clang { 22 class ASTContext; 23 class FieldDecl; 24 class RecordDecl; 25 class CXXRecordDecl; 26 27 /// ASTRecordLayout - 28 /// This class contains layout information for one RecordDecl, 29 /// which is a struct/union/class. The decl represented must be a definition, 30 /// not a forward declaration. 31 /// This class is also used to contain layout information for one 32 /// ObjCInterfaceDecl. FIXME - Find appropriate name. 33 /// These objects are managed by ASTContext. 34 class ASTRecordLayout { 35 public: 36 struct VBaseInfo { 37 /// The offset to this virtual base in the complete-object layout 38 /// of this class. 39 CharUnits VBaseOffset; 40 41 private: 42 /// Whether this virtual base requires a vtordisp field in the 43 /// Microsoft ABI. These fields are required for certain operations 44 /// in constructors and destructors. 45 bool HasVtorDisp; 46 47 public: 48 bool hasVtorDisp() const { return HasVtorDisp; } 49 50 VBaseInfo() : HasVtorDisp(false) {} 51 52 VBaseInfo(CharUnits VBaseOffset, bool hasVtorDisp) : 53 VBaseOffset(VBaseOffset), HasVtorDisp(hasVtorDisp) {} 54 }; 55 56 typedef llvm::DenseMap<const CXXRecordDecl *, VBaseInfo> 57 VBaseOffsetsMapTy; 58 59 private: 60 /// Size - Size of record in characters. 61 CharUnits Size; 62 63 /// DataSize - Size of record in characters without tail padding. 64 CharUnits DataSize; 65 66 // Alignment - Alignment of record in characters. 67 CharUnits Alignment; 68 69 /// FieldOffsets - Array of field offsets in bits. 70 uint64_t *FieldOffsets; 71 72 // FieldCount - Number of fields. 73 unsigned FieldCount; 74 75 /// CXXRecordLayoutInfo - Contains C++ specific layout information. 76 struct CXXRecordLayoutInfo { 77 /// NonVirtualSize - The non-virtual size (in chars) of an object, which is 78 /// the size of the object without virtual bases. 79 CharUnits NonVirtualSize; 80 81 /// NonVirtualAlign - The non-virtual alignment (in chars) of an object, 82 /// which is the alignment of the object without virtual bases. 83 CharUnits NonVirtualAlign; 84 85 /// SizeOfLargestEmptySubobject - The size of the largest empty subobject 86 /// (either a base or a member). Will be zero if the class doesn't contain 87 /// any empty subobjects. 88 CharUnits SizeOfLargestEmptySubobject; 89 90 /// VBPtrOffset - Virtual base table offset (Microsoft-only). 91 CharUnits VBPtrOffset; 92 93 /// HasOwnVFPtr - Does this class provide a virtual function table 94 /// (vtable in Itanium, vftbl in Microsoft) that is independent from 95 /// its base classes? 96 bool HasOwnVFPtr; // TODO: stash this somewhere more efficient 97 98 /// PrimaryBase - The primary base info for this record. 99 llvm::PointerIntPair<const CXXRecordDecl *, 1, bool> PrimaryBase; 100 101 /// FIXME: This should really use a SmallPtrMap, once we have one in LLVM :) 102 typedef llvm::DenseMap<const CXXRecordDecl *, CharUnits> BaseOffsetsMapTy; 103 104 /// BaseOffsets - Contains a map from base classes to their offset. 105 BaseOffsetsMapTy BaseOffsets; 106 107 /// VBaseOffsets - Contains a map from vbase classes to their offset. 108 VBaseOffsetsMapTy VBaseOffsets; 109 }; 110 111 /// CXXInfo - If the record layout is for a C++ record, this will have 112 /// C++ specific information about the record. 113 CXXRecordLayoutInfo *CXXInfo; 114 115 friend class ASTContext; 116 117 ASTRecordLayout(const ASTContext &Ctx, CharUnits size, CharUnits alignment, 118 CharUnits datasize, const uint64_t *fieldoffsets, 119 unsigned fieldcount); 120 121 // Constructor for C++ records. 122 typedef CXXRecordLayoutInfo::BaseOffsetsMapTy BaseOffsetsMapTy; 123 ASTRecordLayout(const ASTContext &Ctx, 124 CharUnits size, CharUnits alignment, 125 bool hasOwnVFPtr, CharUnits vbptroffset, 126 CharUnits datasize, 127 const uint64_t *fieldoffsets, unsigned fieldcount, 128 CharUnits nonvirtualsize, CharUnits nonvirtualalign, 129 CharUnits SizeOfLargestEmptySubobject, 130 const CXXRecordDecl *PrimaryBase, 131 bool IsPrimaryBaseVirtual, 132 const BaseOffsetsMapTy& BaseOffsets, 133 const VBaseOffsetsMapTy& VBaseOffsets); 134 135 ~ASTRecordLayout() {} 136 137 void Destroy(ASTContext &Ctx); 138 139 ASTRecordLayout(const ASTRecordLayout &) LLVM_DELETED_FUNCTION; 140 void operator=(const ASTRecordLayout &) LLVM_DELETED_FUNCTION; 141 public: 142 143 /// getAlignment - Get the record alignment in characters. 144 CharUnits getAlignment() const { return Alignment; } 145 146 /// getSize - Get the record size in characters. 147 CharUnits getSize() const { return Size; } 148 149 /// getFieldCount - Get the number of fields in the layout. 150 unsigned getFieldCount() const { return FieldCount; } 151 152 /// getFieldOffset - Get the offset of the given field index, in 153 /// bits. 154 uint64_t getFieldOffset(unsigned FieldNo) const { 155 assert (FieldNo < FieldCount && "Invalid Field No"); 156 return FieldOffsets[FieldNo]; 157 } 158 159 /// getDataSize() - Get the record data size, which is the record size 160 /// without tail padding, in characters. 161 CharUnits getDataSize() const { 162 return DataSize; 163 } 164 165 /// getNonVirtualSize - Get the non-virtual size (in chars) of an object, 166 /// which is the size of the object without virtual bases. 167 CharUnits getNonVirtualSize() const { 168 assert(CXXInfo && "Record layout does not have C++ specific info!"); 169 170 return CXXInfo->NonVirtualSize; 171 } 172 173 /// getNonVirtualSize - Get the non-virtual alignment (in chars) of an object, 174 /// which is the alignment of the object without virtual bases. 175 CharUnits getNonVirtualAlign() const { 176 assert(CXXInfo && "Record layout does not have C++ specific info!"); 177 178 return CXXInfo->NonVirtualAlign; 179 } 180 181 /// getPrimaryBase - Get the primary base for this record. 182 const CXXRecordDecl *getPrimaryBase() const { 183 assert(CXXInfo && "Record layout does not have C++ specific info!"); 184 185 return CXXInfo->PrimaryBase.getPointer(); 186 } 187 188 /// isPrimaryBaseVirtual - Get whether the primary base for this record 189 /// is virtual or not. 190 bool isPrimaryBaseVirtual() const { 191 assert(CXXInfo && "Record layout does not have C++ specific info!"); 192 193 return CXXInfo->PrimaryBase.getInt(); 194 } 195 196 /// getBaseClassOffset - Get the offset, in chars, for the given base class. 197 CharUnits getBaseClassOffset(const CXXRecordDecl *Base) const { 198 assert(CXXInfo && "Record layout does not have C++ specific info!"); 199 assert(CXXInfo->BaseOffsets.count(Base) && "Did not find base!"); 200 201 return CXXInfo->BaseOffsets[Base]; 202 } 203 204 /// getVBaseClassOffset - Get the offset, in chars, for the given base class. 205 CharUnits getVBaseClassOffset(const CXXRecordDecl *VBase) const { 206 assert(CXXInfo && "Record layout does not have C++ specific info!"); 207 assert(CXXInfo->VBaseOffsets.count(VBase) && "Did not find base!"); 208 209 return CXXInfo->VBaseOffsets[VBase].VBaseOffset; 210 } 211 212 CharUnits getSizeOfLargestEmptySubobject() const { 213 assert(CXXInfo && "Record layout does not have C++ specific info!"); 214 return CXXInfo->SizeOfLargestEmptySubobject; 215 } 216 217 /// hasOwnVFPtr - Does this class provide its own virtual-function 218 /// table pointer, rather than inheriting one from a primary base 219 /// class? If so, it is at offset zero. 220 /// 221 /// This implies that the ABI has no primary base class, meaning 222 /// that it has no base classes that are suitable under the conditions 223 /// of the ABI. 224 bool hasOwnVFPtr() const { 225 assert(CXXInfo && "Record layout does not have C++ specific info!"); 226 return CXXInfo->HasOwnVFPtr; 227 } 228 229 /// getVBPtrOffset - Get the offset for virtual base table pointer. 230 /// This is only meaningful with the Microsoft ABI. 231 CharUnits getVBPtrOffset() const { 232 assert(CXXInfo && "Record layout does not have C++ specific info!"); 233 return CXXInfo->VBPtrOffset; 234 } 235 236 const VBaseOffsetsMapTy &getVBaseOffsetsMap() const { 237 assert(CXXInfo && "Record layout does not have C++ specific info!"); 238 return CXXInfo->VBaseOffsets; 239 } 240 }; 241 242 } // end namespace clang 243 244 #endif 245
