clang  6.0.0svn
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 
52  VBaseInfo(CharUnits VBaseOffset, bool hasVtorDisp) :
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  ASTVector<uint64_t> FieldOffsets;
75 
76  /// CXXRecordLayoutInfo - Contains C++ specific layout information.
77  struct CXXRecordLayoutInfo {
78  /// NonVirtualSize - The non-virtual size (in chars) of an object, which is
79  /// the size of the object without virtual bases.
80  CharUnits NonVirtualSize;
81 
82  /// NonVirtualAlignment - The non-virtual alignment (in chars) of an object,
83  /// which is the alignment of the object without virtual bases.
84  CharUnits NonVirtualAlignment;
85 
86  /// SizeOfLargestEmptySubobject - The size of the largest empty subobject
87  /// (either a base or a member). Will be zero if the class doesn't contain
88  /// any empty subobjects.
89  CharUnits SizeOfLargestEmptySubobject;
90 
91  /// VBPtrOffset - Virtual base table offset (Microsoft-only).
92  CharUnits VBPtrOffset;
93 
94  /// HasOwnVFPtr - Does this class provide a virtual function table
95  /// (vtable in Itanium, vftbl in Microsoft) that is independent from
96  /// its base classes?
97  bool HasOwnVFPtr : 1;
98 
99  /// HasVFPtr - Does this class have a vftable that could be extended by
100  /// a derived class. The class may have inherited this pointer from
101  /// a primary base class.
102  bool HasExtendableVFPtr : 1;
103 
104  /// EndsWithZeroSizedObject - True if this class contains a zero sized
105  /// member or base or a base with a zero sized member or base.
106  /// Only used for MS-ABI.
107  bool EndsWithZeroSizedObject : 1;
108 
109  /// \brief True if this class is zero sized or first base is zero sized or
110  /// has this property. Only used for MS-ABI.
111  bool LeadsWithZeroSizedBase : 1;
112 
113  /// PrimaryBase - The primary base info for this record.
114  llvm::PointerIntPair<const CXXRecordDecl *, 1, bool> PrimaryBase;
115 
116  /// BaseSharingVBPtr - The base we share vbptr with.
117  const CXXRecordDecl *BaseSharingVBPtr;
118 
119  /// FIXME: This should really use a SmallPtrMap, once we have one in LLVM :)
120  typedef llvm::DenseMap<const CXXRecordDecl *, CharUnits> BaseOffsetsMapTy;
121 
122  /// BaseOffsets - Contains a map from base classes to their offset.
123  BaseOffsetsMapTy BaseOffsets;
124 
125  /// VBaseOffsets - Contains a map from vbase classes to their offset.
126  VBaseOffsetsMapTy VBaseOffsets;
127  };
128 
129  /// CXXInfo - If the record layout is for a C++ record, this will have
130  /// C++ specific information about the record.
131  CXXRecordLayoutInfo *CXXInfo;
132 
133  friend class ASTContext;
134 
135  ASTRecordLayout(const ASTContext &Ctx, CharUnits size, CharUnits alignment,
136  CharUnits requiredAlignment, CharUnits datasize,
137  ArrayRef<uint64_t> fieldoffsets);
138 
139  // Constructor for C++ records.
140  typedef CXXRecordLayoutInfo::BaseOffsetsMapTy BaseOffsetsMapTy;
141  ASTRecordLayout(const ASTContext &Ctx,
142  CharUnits size, CharUnits alignment,
143  CharUnits requiredAlignment,
144  bool hasOwnVFPtr, bool hasExtendableVFPtr,
145  CharUnits vbptroffset,
146  CharUnits datasize,
147  ArrayRef<uint64_t> fieldoffsets,
148  CharUnits nonvirtualsize, CharUnits nonvirtualalignment,
149  CharUnits SizeOfLargestEmptySubobject,
150  const CXXRecordDecl *PrimaryBase,
151  bool IsPrimaryBaseVirtual,
152  const CXXRecordDecl *BaseSharingVBPtr,
153  bool EndsWithZeroSizedObject,
154  bool LeadsWithZeroSizedBase,
155  const BaseOffsetsMapTy& BaseOffsets,
156  const VBaseOffsetsMapTy& VBaseOffsets);
157 
158  ~ASTRecordLayout() = default;
159 
160  void Destroy(ASTContext &Ctx);
161 
162  ASTRecordLayout(const ASTRecordLayout &) = delete;
163  void operator=(const ASTRecordLayout &) = delete;
164 public:
165 
166  /// getAlignment - Get the record alignment in characters.
167  CharUnits getAlignment() const { return Alignment; }
168 
169  /// getSize - Get the record size in characters.
170  CharUnits getSize() const { return Size; }
171 
172  /// getFieldCount - Get the number of fields in the layout.
173  unsigned getFieldCount() const { return FieldOffsets.size(); }
174 
175  /// getFieldOffset - Get the offset of the given field index, in
176  /// bits.
177  uint64_t getFieldOffset(unsigned FieldNo) const {
178  return FieldOffsets[FieldNo];
179  }
180 
181  /// getDataSize() - Get the record data size, which is the record size
182  /// without tail padding, in characters.
184  return DataSize;
185  }
186 
187  /// getNonVirtualSize - Get the non-virtual size (in chars) of an object,
188  /// which is the size of the object without virtual bases.
190  assert(CXXInfo && "Record layout does not have C++ specific info!");
191 
192  return CXXInfo->NonVirtualSize;
193  }
194 
195  /// getNonVirtualSize - Get the non-virtual alignment (in chars) of an object,
196  /// which is the alignment of the object without virtual bases.
198  assert(CXXInfo && "Record layout does not have C++ specific info!");
199 
200  return CXXInfo->NonVirtualAlignment;
201  }
202 
203  /// getPrimaryBase - Get the primary base for this record.
204  const CXXRecordDecl *getPrimaryBase() const {
205  assert(CXXInfo && "Record layout does not have C++ specific info!");
206 
207  return CXXInfo->PrimaryBase.getPointer();
208  }
209 
210  /// isPrimaryBaseVirtual - Get whether the primary base for this record
211  /// is virtual or not.
212  bool isPrimaryBaseVirtual() const {
213  assert(CXXInfo && "Record layout does not have C++ specific info!");
214 
215  return CXXInfo->PrimaryBase.getInt();
216  }
217 
218  /// getBaseClassOffset - Get the offset, in chars, for the given base class.
220  assert(CXXInfo && "Record layout does not have C++ specific info!");
221  assert(CXXInfo->BaseOffsets.count(Base) && "Did not find base!");
222 
223  return CXXInfo->BaseOffsets[Base];
224  }
225 
226  /// getVBaseClassOffset - Get the offset, in chars, for the given base class.
228  assert(CXXInfo && "Record layout does not have C++ specific info!");
229  assert(CXXInfo->VBaseOffsets.count(VBase) && "Did not find base!");
230 
231  return CXXInfo->VBaseOffsets[VBase].VBaseOffset;
232  }
233 
235  assert(CXXInfo && "Record layout does not have C++ specific info!");
236  return CXXInfo->SizeOfLargestEmptySubobject;
237  }
238 
239  /// hasOwnVFPtr - Does this class provide its own virtual-function
240  /// table pointer, rather than inheriting one from a primary base
241  /// class? If so, it is at offset zero.
242  ///
243  /// This implies that the ABI has no primary base class, meaning
244  /// that it has no base classes that are suitable under the conditions
245  /// of the ABI.
246  bool hasOwnVFPtr() const {
247  assert(CXXInfo && "Record layout does not have C++ specific info!");
248  return CXXInfo->HasOwnVFPtr;
249  }
250 
251  /// hasVFPtr - Does this class have a virtual function table pointer
252  /// that can be extended by a derived class? This is synonymous with
253  /// this class having a VFPtr at offset zero.
254  bool hasExtendableVFPtr() const {
255  assert(CXXInfo && "Record layout does not have C++ specific info!");
256  return CXXInfo->HasExtendableVFPtr;
257  }
258 
259  /// hasOwnVBPtr - Does this class provide its own virtual-base
260  /// table pointer, rather than inheriting one from a primary base
261  /// class?
262  ///
263  /// This implies that the ABI has no primary base class, meaning
264  /// that it has no base classes that are suitable under the conditions
265  /// of the ABI.
266  bool hasOwnVBPtr() const {
267  assert(CXXInfo && "Record layout does not have C++ specific info!");
268  return hasVBPtr() && !CXXInfo->BaseSharingVBPtr;
269  }
270 
271  /// hasVBPtr - Does this class have a virtual function table pointer.
272  bool hasVBPtr() const {
273  assert(CXXInfo && "Record layout does not have C++ specific info!");
274  return !CXXInfo->VBPtrOffset.isNegative();
275  }
276 
278  return RequiredAlignment;
279  }
280 
281  bool endsWithZeroSizedObject() const {
282  return CXXInfo && CXXInfo->EndsWithZeroSizedObject;
283  }
284 
285  bool leadsWithZeroSizedBase() const {
286  assert(CXXInfo && "Record layout does not have C++ specific info!");
287  return CXXInfo->LeadsWithZeroSizedBase;
288  }
289 
290  /// getVBPtrOffset - Get the offset for virtual base table pointer.
291  /// This is only meaningful with the Microsoft ABI.
293  assert(CXXInfo && "Record layout does not have C++ specific info!");
294  return CXXInfo->VBPtrOffset;
295  }
296 
298  assert(CXXInfo && "Record layout does not have C++ specific info!");
299  return CXXInfo->BaseSharingVBPtr;
300  }
301 
303  assert(CXXInfo && "Record layout does not have C++ specific info!");
304  return CXXInfo->VBaseOffsets;
305  }
306 };
307 
308 } // end namespace clang
309 
310 #endif
bool isPrimaryBaseVirtual() const
isPrimaryBaseVirtual - Get whether the primary base for this record is virtual or not...
Definition: RecordLayout.h:212
llvm::DenseMap< const CXXRecordDecl *, VBaseInfo > VBaseOffsetsMapTy
Definition: RecordLayout.h:57
CharUnits getBaseClassOffset(const CXXRecordDecl *Base) const
getBaseClassOffset - Get the offset, in chars, for the given base class.
Definition: RecordLayout.h:219
CharUnits getAlignment() const
getAlignment - Get the record alignment in characters.
Definition: RecordLayout.h:167
bool hasVBPtr() const
hasVBPtr - Does this class have a virtual function table pointer.
Definition: RecordLayout.h:272
bool hasOwnVFPtr() const
hasOwnVFPtr - Does this class provide its own virtual-function table pointer, rather than inheriting ...
Definition: RecordLayout.h:246
size_type size() const
Definition: ASTVector.h:104
Holds long-lived AST nodes (such as types and decls) that can be referred to throughout the semantic ...
Definition: ASTContext.h:128
CharUnits getVBaseClassOffset(const CXXRecordDecl *VBase) const
getVBaseClassOffset - Get the offset, in chars, for the given base class.
Definition: RecordLayout.h:227
CharUnits - This is an opaque type for sizes expressed in character units.
Definition: CharUnits.h:38
bool endsWithZeroSizedObject() const
Definition: RecordLayout.h:281
const VBaseOffsetsMapTy & getVBaseOffsetsMap() const
Definition: RecordLayout.h:302
ASTRecordLayout - This class contains layout information for one RecordDecl, which is a struct/union/...
Definition: RecordLayout.h:34
CharUnits getSizeOfLargestEmptySubobject() const
Definition: RecordLayout.h:234
const CXXRecordDecl * getPrimaryBase() const
getPrimaryBase - Get the primary base for this record.
Definition: RecordLayout.h:204
unsigned getFieldCount() const
getFieldCount - Get the number of fields in the layout.
Definition: RecordLayout.h:173
bool hasExtendableVFPtr() const
hasVFPtr - Does this class have a virtual function table pointer that can be extended by a derived cl...
Definition: RecordLayout.h:254
CharUnits getVBPtrOffset() const
getVBPtrOffset - Get the offset for virtual base table pointer.
Definition: RecordLayout.h:292
CharUnits getRequiredAlignment() const
Definition: RecordLayout.h:277
uint64_t getFieldOffset(unsigned FieldNo) const
getFieldOffset - Get the offset of the given field index, in bits.
Definition: RecordLayout.h:177
#define false
Definition: stdbool.h:33
CharUnits getDataSize() const
getDataSize() - Get the record data size, which is the record size without tail padding, in characters.
Definition: RecordLayout.h:183
VBaseInfo(CharUnits VBaseOffset, bool hasVtorDisp)
Definition: RecordLayout.h:52
CharUnits getNonVirtualAlignment() const
getNonVirtualSize - Get the non-virtual alignment (in chars) of an object, which is the alignment of ...
Definition: RecordLayout.h:197
Dataflow Directional Tag Classes.
CharUnits getSize() const
getSize - Get the record size in characters.
Definition: RecordLayout.h:170
const CXXRecordDecl * getBaseSharingVBPtr() const
Definition: RecordLayout.h:297
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:266
CharUnits getNonVirtualSize() const
getNonVirtualSize - Get the non-virtual size (in chars) of an object, which is the size of the object...
Definition: RecordLayout.h:189
CharUnits VBaseOffset
The offset to this virtual base in the complete-object layout of this class.
Definition: RecordLayout.h:39
bool hasOwnVBPtr() const
hasOwnVBPtr - Does this class provide its own virtual-base table pointer, rather than inheriting one ...
Definition: RecordLayout.h:266
bool leadsWithZeroSizedBase() const
Definition: RecordLayout.h:285