RecordLayout.h revision b2969b1e50580344891a98f5b241f8351fe371cf
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 21namespace 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. 34class ASTRecordLayout { 35public: 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 59private: 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 : 1; 97 98 /// HasVFPtr - Does this class have a vftable at all (could be inherited 99 /// from its primary base.) 100 bool HasVFPtr : 1; 101 102 /// HasOwnVBPtr - Does this class provide a virtual function table 103 /// (vtable in Itanium, VBtbl in Microsoft) that is independent from 104 /// its base classes? 105 bool HasOwnVBPtr : 1; 106 107 /// AlignAfterVBases - Force appropriate alignment after virtual bases are 108 /// laid out in MS-C++-ABI. 109 bool AlignAfterVBases : 1; 110 111 /// PrimaryBase - The primary base info for this record. 112 llvm::PointerIntPair<const CXXRecordDecl *, 1, bool> PrimaryBase; 113 114 /// FIXME: This should really use a SmallPtrMap, once we have one in LLVM :) 115 typedef llvm::DenseMap<const CXXRecordDecl *, CharUnits> BaseOffsetsMapTy; 116 117 /// BaseOffsets - Contains a map from base classes to their offset. 118 BaseOffsetsMapTy BaseOffsets; 119 120 /// VBaseOffsets - Contains a map from vbase classes to their offset. 121 VBaseOffsetsMapTy VBaseOffsets; 122 }; 123 124 /// CXXInfo - If the record layout is for a C++ record, this will have 125 /// C++ specific information about the record. 126 CXXRecordLayoutInfo *CXXInfo; 127 128 friend class ASTContext; 129 130 ASTRecordLayout(const ASTContext &Ctx, CharUnits size, CharUnits alignment, 131 CharUnits datasize, const uint64_t *fieldoffsets, 132 unsigned fieldcount); 133 134 // Constructor for C++ records. 135 typedef CXXRecordLayoutInfo::BaseOffsetsMapTy BaseOffsetsMapTy; 136 ASTRecordLayout(const ASTContext &Ctx, 137 CharUnits size, CharUnits alignment, 138 bool hasOwnVFPtr, bool hasVFPtr, bool hasOwnVBPtr, 139 CharUnits vbptroffset, 140 CharUnits datasize, 141 const uint64_t *fieldoffsets, unsigned fieldcount, 142 CharUnits nonvirtualsize, CharUnits nonvirtualalign, 143 CharUnits SizeOfLargestEmptySubobject, 144 const CXXRecordDecl *PrimaryBase, 145 bool IsPrimaryBaseVirtual, 146 bool ForceAlign, 147 const BaseOffsetsMapTy& BaseOffsets, 148 const VBaseOffsetsMapTy& VBaseOffsets); 149 150 ~ASTRecordLayout() {} 151 152 void Destroy(ASTContext &Ctx); 153 154 ASTRecordLayout(const ASTRecordLayout &) LLVM_DELETED_FUNCTION; 155 void operator=(const ASTRecordLayout &) LLVM_DELETED_FUNCTION; 156public: 157 158 /// getAlignment - Get the record alignment in characters. 159 CharUnits getAlignment() const { return Alignment; } 160 161 /// getSize - Get the record size in characters. 162 CharUnits getSize() const { return Size; } 163 164 /// getFieldCount - Get the number of fields in the layout. 165 unsigned getFieldCount() const { return FieldCount; } 166 167 /// getFieldOffset - Get the offset of the given field index, in 168 /// bits. 169 uint64_t getFieldOffset(unsigned FieldNo) const { 170 assert (FieldNo < FieldCount && "Invalid Field No"); 171 return FieldOffsets[FieldNo]; 172 } 173 174 /// getDataSize() - Get the record data size, which is the record size 175 /// without tail padding, in characters. 176 CharUnits getDataSize() const { 177 return DataSize; 178 } 179 180 /// getNonVirtualSize - Get the non-virtual size (in chars) of an object, 181 /// which is the size of the object without virtual bases. 182 CharUnits getNonVirtualSize() const { 183 assert(CXXInfo && "Record layout does not have C++ specific info!"); 184 185 return CXXInfo->NonVirtualSize; 186 } 187 188 /// getNonVirtualSize - Get the non-virtual alignment (in chars) of an object, 189 /// which is the alignment of the object without virtual bases. 190 CharUnits getNonVirtualAlign() const { 191 assert(CXXInfo && "Record layout does not have C++ specific info!"); 192 193 return CXXInfo->NonVirtualAlign; 194 } 195 196 /// getPrimaryBase - Get the primary base for this record. 197 const CXXRecordDecl *getPrimaryBase() const { 198 assert(CXXInfo && "Record layout does not have C++ specific info!"); 199 200 return CXXInfo->PrimaryBase.getPointer(); 201 } 202 203 /// isPrimaryBaseVirtual - Get whether the primary base for this record 204 /// is virtual or not. 205 bool isPrimaryBaseVirtual() const { 206 assert(CXXInfo && "Record layout does not have C++ specific info!"); 207 208 return CXXInfo->PrimaryBase.getInt(); 209 } 210 211 /// getBaseClassOffset - Get the offset, in chars, for the given base class. 212 CharUnits getBaseClassOffset(const CXXRecordDecl *Base) const { 213 assert(CXXInfo && "Record layout does not have C++ specific info!"); 214 assert(CXXInfo->BaseOffsets.count(Base) && "Did not find base!"); 215 216 return CXXInfo->BaseOffsets[Base]; 217 } 218 219 /// getVBaseClassOffset - Get the offset, in chars, for the given base class. 220 CharUnits getVBaseClassOffset(const CXXRecordDecl *VBase) const { 221 assert(CXXInfo && "Record layout does not have C++ specific info!"); 222 assert(CXXInfo->VBaseOffsets.count(VBase) && "Did not find base!"); 223 224 return CXXInfo->VBaseOffsets[VBase].VBaseOffset; 225 } 226 227 CharUnits getSizeOfLargestEmptySubobject() const { 228 assert(CXXInfo && "Record layout does not have C++ specific info!"); 229 return CXXInfo->SizeOfLargestEmptySubobject; 230 } 231 232 /// hasOwnVFPtr - Does this class provide its own virtual-function 233 /// table pointer, rather than inheriting one from a primary base 234 /// class? If so, it is at offset zero. 235 /// 236 /// This implies that the ABI has no primary base class, meaning 237 /// that it has no base classes that are suitable under the conditions 238 /// of the ABI. 239 bool hasOwnVFPtr() const { 240 assert(CXXInfo && "Record layout does not have C++ specific info!"); 241 return CXXInfo->HasOwnVFPtr; 242 } 243 244 /// hasVFPtr - Does this class have a virtual function table pointer. 245 bool hasVFPtr() const { 246 assert(CXXInfo && "Record layout does not have C++ specific info!"); 247 return CXXInfo->HasVFPtr; 248 } 249 250 /// hasOwnVBPtr - Does this class provide its own virtual-base 251 /// table pointer, rather than inheriting one from a primary base 252 /// class? 253 /// 254 /// This implies that the ABI has no primary base class, meaning 255 /// that it has no base classes that are suitable under the conditions 256 /// of the ABI. 257 bool hasOwnVBPtr() const { 258 assert(CXXInfo && "Record layout does not have C++ specific info!"); 259 return CXXInfo->HasOwnVBPtr; 260 } 261 262 /// hasVBPtr - Does this class have a virtual function table pointer. 263 bool hasVBPtr() const { 264 assert(CXXInfo && "Record layout does not have C++ specific info!"); 265 return !CXXInfo->VBPtrOffset.isNegative(); 266 } 267 268 bool getAlignAfterVBases() const { 269 assert(CXXInfo && "Record layout does not have C++ specific info!"); 270 return CXXInfo->AlignAfterVBases; 271 } 272 273 /// getVBPtrOffset - Get the offset for virtual base table pointer. 274 /// This is only meaningful with the Microsoft ABI. 275 CharUnits getVBPtrOffset() const { 276 assert(CXXInfo && "Record layout does not have C++ specific info!"); 277 return CXXInfo->VBPtrOffset; 278 } 279 280 const VBaseOffsetsMapTy &getVBaseOffsetsMap() const { 281 assert(CXXInfo && "Record layout does not have C++ specific info!"); 282 return CXXInfo->VBaseOffsets; 283 } 284}; 285 286} // end namespace clang 287 288#endif 289