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 /// RequiredAlignment - The required alignment of the object. In the MS-ABI 70 /// the __declspec(align()) trumps #pramga pack and must always be obeyed. 71 CharUnits RequiredAlignment; 72 73 /// FieldOffsets - Array of field offsets in bits. 74 uint64_t *FieldOffsets; 75 76 // FieldCount - Number of fields. 77 unsigned FieldCount; 78 79 /// CXXRecordLayoutInfo - Contains C++ specific layout information. 80 struct CXXRecordLayoutInfo { 81 /// NonVirtualSize - The non-virtual size (in chars) of an object, which is 82 /// the size of the object without virtual bases. 83 CharUnits NonVirtualSize; 84 85 /// NonVirtualAlignment - The non-virtual alignment (in chars) of an object, 86 /// which is the alignment of the object without virtual bases. 87 CharUnits NonVirtualAlignment; 88 89 /// SizeOfLargestEmptySubobject - The size of the largest empty subobject 90 /// (either a base or a member). Will be zero if the class doesn't contain 91 /// any empty subobjects. 92 CharUnits SizeOfLargestEmptySubobject; 93 94 /// VBPtrOffset - Virtual base table offset (Microsoft-only). 95 CharUnits VBPtrOffset; 96 97 /// HasOwnVFPtr - Does this class provide a virtual function table 98 /// (vtable in Itanium, vftbl in Microsoft) that is independent from 99 /// its base classes? 100 bool HasOwnVFPtr : 1; 101 102 /// HasVFPtr - Does this class have a vftable that could be extended by 103 /// a derived class. The class may have inherited this pointer from 104 /// a primary base class. 105 bool HasExtendableVFPtr : 1; 106 107 /// HasZeroSizedSubObject - True if this class contains a zero sized member 108 /// or base or a base with a zero sized member or base. Only used for 109 /// MS-ABI. 110 bool HasZeroSizedSubObject : 1; 111 112 /// \brief True if this class is zero sized or first base is zero sized or 113 /// has this property. Only used for MS-ABI. 114 bool LeadsWithZeroSizedBase : 1; 115 116 /// PrimaryBase - The primary base info for this record. 117 llvm::PointerIntPair<const CXXRecordDecl *, 1, bool> PrimaryBase; 118 119 /// BaseSharingVBPtr - The base we share vbptr with. 120 const CXXRecordDecl *BaseSharingVBPtr; 121 122 /// FIXME: This should really use a SmallPtrMap, once we have one in LLVM :) 123 typedef llvm::DenseMap<const CXXRecordDecl *, CharUnits> BaseOffsetsMapTy; 124 125 /// BaseOffsets - Contains a map from base classes to their offset. 126 BaseOffsetsMapTy BaseOffsets; 127 128 /// VBaseOffsets - Contains a map from vbase classes to their offset. 129 VBaseOffsetsMapTy VBaseOffsets; 130 }; 131 132 /// CXXInfo - If the record layout is for a C++ record, this will have 133 /// C++ specific information about the record. 134 CXXRecordLayoutInfo *CXXInfo; 135 136 friend class ASTContext; 137 138 ASTRecordLayout(const ASTContext &Ctx, CharUnits size, CharUnits alignment, 139 CharUnits requiredAlignment, 140 CharUnits datasize, const uint64_t *fieldoffsets, 141 unsigned fieldcount); 142 143 // Constructor for C++ records. 144 typedef CXXRecordLayoutInfo::BaseOffsetsMapTy BaseOffsetsMapTy; 145 ASTRecordLayout(const ASTContext &Ctx, 146 CharUnits size, CharUnits alignment, 147 CharUnits requiredAlignment, 148 bool hasOwnVFPtr, bool hasExtendableVFPtr, 149 CharUnits vbptroffset, 150 CharUnits datasize, 151 const uint64_t *fieldoffsets, unsigned fieldcount, 152 CharUnits nonvirtualsize, CharUnits nonvirtualalignment, 153 CharUnits SizeOfLargestEmptySubobject, 154 const CXXRecordDecl *PrimaryBase, 155 bool IsPrimaryBaseVirtual, 156 const CXXRecordDecl *BaseSharingVBPtr, 157 bool HasZeroSizedSubObject, 158 bool LeadsWithZeroSizedBase, 159 const BaseOffsetsMapTy& BaseOffsets, 160 const VBaseOffsetsMapTy& VBaseOffsets); 161 162 ~ASTRecordLayout() {} 163 164 void Destroy(ASTContext &Ctx); 165 166 ASTRecordLayout(const ASTRecordLayout &) LLVM_DELETED_FUNCTION; 167 void operator=(const ASTRecordLayout &) LLVM_DELETED_FUNCTION; 168 public: 169 170 /// getAlignment - Get the record alignment in characters. 171 CharUnits getAlignment() const { return Alignment; } 172 173 /// getSize - Get the record size in characters. 174 CharUnits getSize() const { return Size; } 175 176 /// getFieldCount - Get the number of fields in the layout. 177 unsigned getFieldCount() const { return FieldCount; } 178 179 /// getFieldOffset - Get the offset of the given field index, in 180 /// bits. 181 uint64_t getFieldOffset(unsigned FieldNo) const { 182 assert (FieldNo < FieldCount && "Invalid Field No"); 183 return FieldOffsets[FieldNo]; 184 } 185 186 /// getDataSize() - Get the record data size, which is the record size 187 /// without tail padding, in characters. 188 CharUnits getDataSize() const { 189 return DataSize; 190 } 191 192 /// getNonVirtualSize - Get the non-virtual size (in chars) of an object, 193 /// which is the size of the object without virtual bases. 194 CharUnits getNonVirtualSize() const { 195 assert(CXXInfo && "Record layout does not have C++ specific info!"); 196 197 return CXXInfo->NonVirtualSize; 198 } 199 200 /// getNonVirtualSize - Get the non-virtual alignment (in chars) of an object, 201 /// which is the alignment of the object without virtual bases. 202 CharUnits getNonVirtualAlignment() const { 203 assert(CXXInfo && "Record layout does not have C++ specific info!"); 204 205 return CXXInfo->NonVirtualAlignment; 206 } 207 208 /// getPrimaryBase - Get the primary base for this record. 209 const CXXRecordDecl *getPrimaryBase() const { 210 assert(CXXInfo && "Record layout does not have C++ specific info!"); 211 212 return CXXInfo->PrimaryBase.getPointer(); 213 } 214 215 /// isPrimaryBaseVirtual - Get whether the primary base for this record 216 /// is virtual or not. 217 bool isPrimaryBaseVirtual() const { 218 assert(CXXInfo && "Record layout does not have C++ specific info!"); 219 220 return CXXInfo->PrimaryBase.getInt(); 221 } 222 223 /// getBaseClassOffset - Get the offset, in chars, for the given base class. 224 CharUnits getBaseClassOffset(const CXXRecordDecl *Base) const { 225 assert(CXXInfo && "Record layout does not have C++ specific info!"); 226 assert(CXXInfo->BaseOffsets.count(Base) && "Did not find base!"); 227 228 return CXXInfo->BaseOffsets[Base]; 229 } 230 231 /// getVBaseClassOffset - Get the offset, in chars, for the given base class. 232 CharUnits getVBaseClassOffset(const CXXRecordDecl *VBase) const { 233 assert(CXXInfo && "Record layout does not have C++ specific info!"); 234 assert(CXXInfo->VBaseOffsets.count(VBase) && "Did not find base!"); 235 236 return CXXInfo->VBaseOffsets[VBase].VBaseOffset; 237 } 238 239 CharUnits getSizeOfLargestEmptySubobject() const { 240 assert(CXXInfo && "Record layout does not have C++ specific info!"); 241 return CXXInfo->SizeOfLargestEmptySubobject; 242 } 243 244 /// hasOwnVFPtr - Does this class provide its own virtual-function 245 /// table pointer, rather than inheriting one from a primary base 246 /// class? If so, it is at offset zero. 247 /// 248 /// This implies that the ABI has no primary base class, meaning 249 /// that it has no base classes that are suitable under the conditions 250 /// of the ABI. 251 bool hasOwnVFPtr() const { 252 assert(CXXInfo && "Record layout does not have C++ specific info!"); 253 return CXXInfo->HasOwnVFPtr; 254 } 255 256 /// hasVFPtr - Does this class have a virtual function table pointer 257 /// that can be extended by a derived class? This is synonymous with 258 /// this class having a VFPtr at offset zero. 259 bool hasExtendableVFPtr() const { 260 assert(CXXInfo && "Record layout does not have C++ specific info!"); 261 return CXXInfo->HasExtendableVFPtr; 262 } 263 264 /// hasOwnVBPtr - Does this class provide its own virtual-base 265 /// table pointer, rather than inheriting one from a primary base 266 /// class? 267 /// 268 /// This implies that the ABI has no primary base class, meaning 269 /// that it has no base classes that are suitable under the conditions 270 /// of the ABI. 271 bool hasOwnVBPtr() const { 272 assert(CXXInfo && "Record layout does not have C++ specific info!"); 273 return hasVBPtr() && !CXXInfo->BaseSharingVBPtr; 274 } 275 276 /// hasVBPtr - Does this class have a virtual function table pointer. 277 bool hasVBPtr() const { 278 assert(CXXInfo && "Record layout does not have C++ specific info!"); 279 return !CXXInfo->VBPtrOffset.isNegative(); 280 } 281 282 CharUnits getRequiredAlignment() const { 283 return RequiredAlignment; 284 } 285 286 bool hasZeroSizedSubObject() const { 287 return CXXInfo && CXXInfo->HasZeroSizedSubObject; 288 } 289 290 bool leadsWithZeroSizedBase() const { 291 assert(CXXInfo && "Record layout does not have C++ specific info!"); 292 return CXXInfo->LeadsWithZeroSizedBase; 293 } 294 295 /// getVBPtrOffset - Get the offset for virtual base table pointer. 296 /// This is only meaningful with the Microsoft ABI. 297 CharUnits getVBPtrOffset() const { 298 assert(CXXInfo && "Record layout does not have C++ specific info!"); 299 return CXXInfo->VBPtrOffset; 300 } 301 302 const CXXRecordDecl *getBaseSharingVBPtr() const { 303 assert(CXXInfo && "Record layout does not have C++ specific info!"); 304 return CXXInfo->BaseSharingVBPtr; 305 } 306 307 const VBaseOffsetsMapTy &getVBaseOffsetsMap() const { 308 assert(CXXInfo && "Record layout does not have C++ specific info!"); 309 return CXXInfo->VBaseOffsets; 310 } 311 }; 312 313 } // end namespace clang 314 315 #endif 316
