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