RecordLayout.h revision 6acb04f755cfc73d05772457d70aeb5adfaf6d8f
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 /// AlignAfterVBases - Force appropriate alignment after virtual bases are 103 /// laid out in MS-C++-ABI. 104 bool AlignAfterVBases : 1; 105 106 /// PrimaryBase - The primary base info for this record. 107 llvm::PointerIntPair<const CXXRecordDecl *, 1, bool> PrimaryBase; 108 109 /// BaseSharingVBPtr - The base we share vbptr with. 110 const CXXRecordDecl *BaseSharingVBPtr; 111 112 /// FIXME: This should really use a SmallPtrMap, once we have one in LLVM :) 113 typedef llvm::DenseMap<const CXXRecordDecl *, CharUnits> BaseOffsetsMapTy; 114 115 /// BaseOffsets - Contains a map from base classes to their offset. 116 BaseOffsetsMapTy BaseOffsets; 117 118 /// VBaseOffsets - Contains a map from vbase classes to their offset. 119 VBaseOffsetsMapTy VBaseOffsets; 120 }; 121 122 /// CXXInfo - If the record layout is for a C++ record, this will have 123 /// C++ specific information about the record. 124 CXXRecordLayoutInfo *CXXInfo; 125 126 friend class ASTContext; 127 128 ASTRecordLayout(const ASTContext &Ctx, CharUnits size, CharUnits alignment, 129 CharUnits datasize, const uint64_t *fieldoffsets, 130 unsigned fieldcount); 131 132 // Constructor for C++ records. 133 typedef CXXRecordLayoutInfo::BaseOffsetsMapTy BaseOffsetsMapTy; 134 ASTRecordLayout(const ASTContext &Ctx, 135 CharUnits size, CharUnits alignment, 136 bool hasOwnVFPtr, bool hasVFPtr, 137 CharUnits vbptroffset, 138 CharUnits datasize, 139 const uint64_t *fieldoffsets, unsigned fieldcount, 140 CharUnits nonvirtualsize, CharUnits nonvirtualalign, 141 CharUnits SizeOfLargestEmptySubobject, 142 const CXXRecordDecl *PrimaryBase, 143 bool IsPrimaryBaseVirtual, 144 const CXXRecordDecl *BaseSharingVBPtr, 145 bool ForceAlign, 146 const BaseOffsetsMapTy& BaseOffsets, 147 const VBaseOffsetsMapTy& VBaseOffsets); 148 149 ~ASTRecordLayout() {} 150 151 void Destroy(ASTContext &Ctx); 152 153 ASTRecordLayout(const ASTRecordLayout &) LLVM_DELETED_FUNCTION; 154 void operator=(const ASTRecordLayout &) LLVM_DELETED_FUNCTION; 155public: 156 157 /// getAlignment - Get the record alignment in characters. 158 CharUnits getAlignment() const { return Alignment; } 159 160 /// getSize - Get the record size in characters. 161 CharUnits getSize() const { return Size; } 162 163 /// getFieldCount - Get the number of fields in the layout. 164 unsigned getFieldCount() const { return FieldCount; } 165 166 /// getFieldOffset - Get the offset of the given field index, in 167 /// bits. 168 uint64_t getFieldOffset(unsigned FieldNo) const { 169 assert (FieldNo < FieldCount && "Invalid Field No"); 170 return FieldOffsets[FieldNo]; 171 } 172 173 /// getDataSize() - Get the record data size, which is the record size 174 /// without tail padding, in characters. 175 CharUnits getDataSize() const { 176 return DataSize; 177 } 178 179 /// getNonVirtualSize - Get the non-virtual size (in chars) of an object, 180 /// which is the size of the object without virtual bases. 181 CharUnits getNonVirtualSize() const { 182 assert(CXXInfo && "Record layout does not have C++ specific info!"); 183 184 return CXXInfo->NonVirtualSize; 185 } 186 187 /// getNonVirtualSize - Get the non-virtual alignment (in chars) of an object, 188 /// which is the alignment of the object without virtual bases. 189 CharUnits getNonVirtualAlign() const { 190 assert(CXXInfo && "Record layout does not have C++ specific info!"); 191 192 return CXXInfo->NonVirtualAlign; 193 } 194 195 /// getPrimaryBase - Get the primary base for this record. 196 const CXXRecordDecl *getPrimaryBase() const { 197 assert(CXXInfo && "Record layout does not have C++ specific info!"); 198 199 return CXXInfo->PrimaryBase.getPointer(); 200 } 201 202 /// isPrimaryBaseVirtual - Get whether the primary base for this record 203 /// is virtual or not. 204 bool isPrimaryBaseVirtual() const { 205 assert(CXXInfo && "Record layout does not have C++ specific info!"); 206 207 return CXXInfo->PrimaryBase.getInt(); 208 } 209 210 /// getBaseClassOffset - Get the offset, in chars, for the given base class. 211 CharUnits getBaseClassOffset(const CXXRecordDecl *Base) const { 212 assert(CXXInfo && "Record layout does not have C++ specific info!"); 213 assert(CXXInfo->BaseOffsets.count(Base) && "Did not find base!"); 214 215 return CXXInfo->BaseOffsets[Base]; 216 } 217 218 /// getVBaseClassOffset - Get the offset, in chars, for the given base class. 219 CharUnits getVBaseClassOffset(const CXXRecordDecl *VBase) const { 220 assert(CXXInfo && "Record layout does not have C++ specific info!"); 221 assert(CXXInfo->VBaseOffsets.count(VBase) && "Did not find base!"); 222 223 return CXXInfo->VBaseOffsets[VBase].VBaseOffset; 224 } 225 226 CharUnits getSizeOfLargestEmptySubobject() const { 227 assert(CXXInfo && "Record layout does not have C++ specific info!"); 228 return CXXInfo->SizeOfLargestEmptySubobject; 229 } 230 231 /// hasOwnVFPtr - Does this class provide its own virtual-function 232 /// table pointer, rather than inheriting one from a primary base 233 /// class? If so, it is at offset zero. 234 /// 235 /// This implies that the ABI has no primary base class, meaning 236 /// that it has no base classes that are suitable under the conditions 237 /// of the ABI. 238 bool hasOwnVFPtr() const { 239 assert(CXXInfo && "Record layout does not have C++ specific info!"); 240 return CXXInfo->HasOwnVFPtr; 241 } 242 243 /// hasVFPtr - Does this class have a virtual function table pointer. 244 bool hasVFPtr() const { 245 assert(CXXInfo && "Record layout does not have C++ specific info!"); 246 return CXXInfo->HasVFPtr; 247 } 248 249 /// hasOwnVBPtr - Does this class provide its own virtual-base 250 /// table pointer, rather than inheriting one from a primary base 251 /// class? 252 /// 253 /// This implies that the ABI has no primary base class, meaning 254 /// that it has no base classes that are suitable under the conditions 255 /// of the ABI. 256 bool hasOwnVBPtr() const { 257 assert(CXXInfo && "Record layout does not have C++ specific info!"); 258 return hasVBPtr() && !CXXInfo->BaseSharingVBPtr; 259 } 260 261 /// hasVBPtr - Does this class have a virtual function table pointer. 262 bool hasVBPtr() const { 263 assert(CXXInfo && "Record layout does not have C++ specific info!"); 264 return !CXXInfo->VBPtrOffset.isNegative(); 265 } 266 267 bool getAlignAfterVBases() const { 268 assert(CXXInfo && "Record layout does not have C++ specific info!"); 269 return CXXInfo->AlignAfterVBases; 270 } 271 272 /// getVBPtrOffset - Get the offset for virtual base table pointer. 273 /// This is only meaningful with the Microsoft ABI. 274 CharUnits getVBPtrOffset() const { 275 assert(CXXInfo && "Record layout does not have C++ specific info!"); 276 return CXXInfo->VBPtrOffset; 277 } 278 279 const CXXRecordDecl *getBaseSharingVBPtr() const { 280 assert(CXXInfo && "Record layout does not have C++ specific info!"); 281 return CXXInfo->BaseSharingVBPtr; 282 } 283 284 const VBaseOffsetsMapTy &getVBaseOffsetsMap() const { 285 assert(CXXInfo && "Record layout does not have C++ specific info!"); 286 return CXXInfo->VBaseOffsets; 287 } 288}; 289 290} // end namespace clang 291 292#endif 293