1 //===--- RecordLayout.h - Layout information for a struct/union -*- C++ -*-===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file defines the RecordLayout interface.
12 //===----------------------------------------------------------------------===//
14 #ifndef LLVM_CLANG_AST_LAYOUTINFO_H
15 #define LLVM_CLANG_AST_LAYOUTINFO_H
17 #include "clang/AST/CharUnits.h"
18 #include "clang/AST/DeclCXX.h"
19 #include "llvm/ADT/DenseMap.h"
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 {
37 /// The offset to this virtual base in the complete-object layout
39 CharUnits VBaseOffset;
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.
48 bool hasVtorDisp() const { return HasVtorDisp; }
50 VBaseInfo() : HasVtorDisp(false) {}
52 VBaseInfo(CharUnits VBaseOffset, bool hasVtorDisp) :
53 VBaseOffset(VBaseOffset), HasVtorDisp(hasVtorDisp) {}
56 typedef llvm::DenseMap<const CXXRecordDecl *, VBaseInfo>
60 /// Size - Size of record in characters.
63 /// DataSize - Size of record in characters without tail padding.
66 // Alignment - Alignment of record in characters.
69 /// FieldOffsets - Array of field offsets in bits.
70 uint64_t *FieldOffsets;
72 // FieldCount - Number of fields.
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;
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;
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;
90 /// VBPtrOffset - Virtual base table offset (Microsoft-only).
91 CharUnits VBPtrOffset;
93 /// HasOwnVFPtr - Does this class provide a virtual function table
94 /// (vtable in Itanium, vftbl in Microsoft) that is independent from
98 /// HasVFPtr - Does this class have a vftable that could be extended by
99 /// a derived class. The class may have inherited this pointer from
100 /// a primary base class.
101 bool HasExtendableVFPtr : 1;
103 /// AlignAfterVBases - Force appropriate alignment after virtual bases are
104 /// laid out in MS-C++-ABI.
105 bool AlignAfterVBases : 1;
107 /// PrimaryBase - The primary base info for this record.
108 llvm::PointerIntPair<const CXXRecordDecl *, 1, bool> PrimaryBase;
110 /// BaseSharingVBPtr - The base we share vbptr with.
111 const CXXRecordDecl *BaseSharingVBPtr;
113 /// FIXME: This should really use a SmallPtrMap, once we have one in LLVM :)
114 typedef llvm::DenseMap<const CXXRecordDecl *, CharUnits> BaseOffsetsMapTy;
116 /// BaseOffsets - Contains a map from base classes to their offset.
117 BaseOffsetsMapTy BaseOffsets;
119 /// VBaseOffsets - Contains a map from vbase classes to their offset.
120 VBaseOffsetsMapTy VBaseOffsets;
123 /// CXXInfo - If the record layout is for a C++ record, this will have
124 /// C++ specific information about the record.
125 CXXRecordLayoutInfo *CXXInfo;
127 friend class ASTContext;
129 ASTRecordLayout(const ASTContext &Ctx, CharUnits size, CharUnits alignment,
130 CharUnits datasize, const uint64_t *fieldoffsets,
131 unsigned fieldcount);
133 // Constructor for C++ records.
134 typedef CXXRecordLayoutInfo::BaseOffsetsMapTy BaseOffsetsMapTy;
135 ASTRecordLayout(const ASTContext &Ctx,
136 CharUnits size, CharUnits alignment,
137 bool hasOwnVFPtr, bool hasExtendableVFPtr,
138 CharUnits vbptroffset,
140 const uint64_t *fieldoffsets, unsigned fieldcount,
141 CharUnits nonvirtualsize, CharUnits nonvirtualalign,
142 CharUnits SizeOfLargestEmptySubobject,
143 const CXXRecordDecl *PrimaryBase,
144 bool IsPrimaryBaseVirtual,
145 const CXXRecordDecl *BaseSharingVBPtr,
147 const BaseOffsetsMapTy& BaseOffsets,
148 const VBaseOffsetsMapTy& VBaseOffsets);
150 ~ASTRecordLayout() {}
152 void Destroy(ASTContext &Ctx);
154 ASTRecordLayout(const ASTRecordLayout &) LLVM_DELETED_FUNCTION;
155 void operator=(const ASTRecordLayout &) LLVM_DELETED_FUNCTION;
158 /// getAlignment - Get the record alignment in characters.
159 CharUnits getAlignment() const { return Alignment; }
161 /// getSize - Get the record size in characters.
162 CharUnits getSize() const { return Size; }
164 /// getFieldCount - Get the number of fields in the layout.
165 unsigned getFieldCount() const { return FieldCount; }
167 /// getFieldOffset - Get the offset of the given field index, in
169 uint64_t getFieldOffset(unsigned FieldNo) const {
170 assert (FieldNo < FieldCount && "Invalid Field No");
171 return FieldOffsets[FieldNo];
174 /// getDataSize() - Get the record data size, which is the record size
175 /// without tail padding, in characters.
176 CharUnits getDataSize() const {
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!");
185 return CXXInfo->NonVirtualSize;
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!");
193 return CXXInfo->NonVirtualAlign;
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!");
200 return CXXInfo->PrimaryBase.getPointer();
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!");
208 return CXXInfo->PrimaryBase.getInt();
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!");
216 return CXXInfo->BaseOffsets[Base];
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!");
224 return CXXInfo->VBaseOffsets[VBase].VBaseOffset;
227 CharUnits getSizeOfLargestEmptySubobject() const {
228 assert(CXXInfo && "Record layout does not have C++ specific info!");
229 return CXXInfo->SizeOfLargestEmptySubobject;
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.
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
239 bool hasOwnVFPtr() const {
240 assert(CXXInfo && "Record layout does not have C++ specific info!");
241 return CXXInfo->HasOwnVFPtr;
244 /// hasVFPtr - Does this class have a virtual function table pointer
245 /// that can be extended by a derived class? This is synonymous with
246 /// this class having a VFPtr at offset zero.
247 bool hasExtendableVFPtr() const {
248 assert(CXXInfo && "Record layout does not have C++ specific info!");
249 return CXXInfo->HasExtendableVFPtr;
252 /// hasOwnVBPtr - Does this class provide its own virtual-base
253 /// table pointer, rather than inheriting one from a primary base
256 /// This implies that the ABI has no primary base class, meaning
257 /// that it has no base classes that are suitable under the conditions
259 bool hasOwnVBPtr() const {
260 assert(CXXInfo && "Record layout does not have C++ specific info!");
261 return hasVBPtr() && !CXXInfo->BaseSharingVBPtr;
264 /// hasVBPtr - Does this class have a virtual function table pointer.
265 bool hasVBPtr() const {
266 assert(CXXInfo && "Record layout does not have C++ specific info!");
267 return !CXXInfo->VBPtrOffset.isNegative();
270 bool getAlignAfterVBases() const {
271 assert(CXXInfo && "Record layout does not have C++ specific info!");
272 return CXXInfo->AlignAfterVBases;
275 /// getVBPtrOffset - Get the offset for virtual base table pointer.
276 /// This is only meaningful with the Microsoft ABI.
277 CharUnits getVBPtrOffset() const {
278 assert(CXXInfo && "Record layout does not have C++ specific info!");
279 return CXXInfo->VBPtrOffset;
282 const CXXRecordDecl *getBaseSharingVBPtr() const {
283 assert(CXXInfo && "Record layout does not have C++ specific info!");
284 return CXXInfo->BaseSharingVBPtr;
287 const VBaseOffsetsMapTy &getVBaseOffsetsMap() const {
288 assert(CXXInfo && "Record layout does not have C++ specific info!");
289 return CXXInfo->VBaseOffsets;
293 } // end namespace clang