clang  3.7.0
RecordLayout.h
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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_RECORDLAYOUT_H
15 #define LLVM_CLANG_AST_RECORDLAYOUT_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.
35 public:
36  struct VBaseInfo {
37  /// The offset to this virtual base in the complete-object layout
38  /// of this class.
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 
53  VBaseOffset(VBaseOffset), HasVtorDisp(hasVtorDisp) {}
54  };
55 
56  typedef llvm::DenseMap<const CXXRecordDecl *, VBaseInfo>
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() = default;
163 
164  void Destroy(ASTContext &Ctx);
165 
166  ASTRecordLayout(const ASTRecordLayout &) = delete;
167  void operator=(const ASTRecordLayout &) = delete;
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.
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.
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.
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.
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.
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 
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 
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.
298  assert(CXXInfo && "Record layout does not have C++ specific info!");
299  return CXXInfo->VBPtrOffset;
300  }
301 
303  assert(CXXInfo && "Record layout does not have C++ specific info!");
304  return CXXInfo->BaseSharingVBPtr;
305  }
306 
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
llvm::DenseMap< const CXXRecordDecl *, VBaseInfo > VBaseOffsetsMapTy
Definition: RecordLayout.h:57
unsigned getFieldCount() const
getFieldCount - Get the number of fields in the layout.
Definition: RecordLayout.h:177
bool hasZeroSizedSubObject() const
Definition: RecordLayout.h:286
CharUnits getAlignment() const
getAlignment - Get the record alignment in characters.
Definition: RecordLayout.h:171
CharUnits getVBaseClassOffset(const CXXRecordDecl *VBase) const
getVBaseClassOffset - Get the offset, in chars, for the given base class.
Definition: RecordLayout.h:232
bool isPrimaryBaseVirtual() const
Definition: RecordLayout.h:217
Holds long-lived AST nodes (such as types and decls) that can be referred to throughout the semantic ...
Definition: ASTContext.h:89
CharUnits getRequiredAlignment() const
Definition: RecordLayout.h:282
bool hasVBPtr() const
hasVBPtr - Does this class have a virtual function table pointer.
Definition: RecordLayout.h:277
uint64_t getFieldOffset(unsigned FieldNo) const
Definition: RecordLayout.h:181
bool hasOwnVBPtr() const
Definition: RecordLayout.h:271
bool leadsWithZeroSizedBase() const
Definition: RecordLayout.h:290
CharUnits getNonVirtualAlignment() const
Definition: RecordLayout.h:202
CharUnits getBaseClassOffset(const CXXRecordDecl *Base) const
getBaseClassOffset - Get the offset, in chars, for the given base class.
Definition: RecordLayout.h:224
const CXXRecordDecl * getBaseSharingVBPtr() const
Definition: RecordLayout.h:302
CharUnits getVBPtrOffset() const
Definition: RecordLayout.h:297
CharUnits getSizeOfLargestEmptySubobject() const
Definition: RecordLayout.h:239
#define false
Definition: stdbool.h:33
CharUnits getSize() const
getSize - Get the record size in characters.
Definition: RecordLayout.h:174
const CXXRecordDecl * getPrimaryBase() const
getPrimaryBase - Get the primary base for this record.
Definition: RecordLayout.h:209
bool hasExtendableVFPtr() const
Definition: RecordLayout.h:259
const VBaseOffsetsMapTy & getVBaseOffsetsMap() const
Definition: RecordLayout.h:307
VBaseInfo(CharUnits VBaseOffset, bool hasVtorDisp)
Definition: RecordLayout.h:52
CharUnits getNonVirtualSize() const
Definition: RecordLayout.h:194
Defines the C++ Decl subclasses, other than those for templates (found in DeclTemplate.h) and friends (in DeclFriend.h).
Represents a C++ struct/union/class.
Definition: DeclCXX.h:285
CharUnits getDataSize() const
Definition: RecordLayout.h:188
bool hasOwnVFPtr() const
Definition: RecordLayout.h:251