RecordLayout.h source code [clang_source_code/include/clang/AST/RecordLayout.h]

1	//===- RecordLayout.h - Layout information for a struct/union ---- C++ --===//
2	//
3	// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4	// See https://llvm.org/LICENSE.txt for license information.
5	// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6	//
7	//===----------------------------------------------------------------------===//
8	//
9	// This file defines the RecordLayout interface.
10	//
11	//===----------------------------------------------------------------------===//
12
13	#ifndef LLVM_CLANG_AST_RECORDLAYOUT_H
14	#define LLVM_CLANG_AST_RECORDLAYOUT_H
15
16	#include "clang/AST/ASTVector.h"
17	#include "clang/AST/CharUnits.h"
18	#include "clang/AST/DeclCXX.h"
19	#include "clang/Basic/LLVM.h"
20	#include "llvm/ADT/ArrayRef.h"
21	#include "llvm/ADT/DenseMap.h"
22	#include "llvm/ADT/PointerIntPair.h"
23	#include <cassert>
24	#include <cstdint>
25
26	namespace clang {
27
28	class ASTContext;
29	class CXXRecordDecl;
30
31	/// ASTRecordLayout -
32	/// This class contains layout information for one RecordDecl,
33	/// which is a struct/union/class. The decl represented must be a definition,
34	/// not a forward declaration.
35	/// This class is also used to contain layout information for one
36	/// ObjCInterfaceDecl. FIXME - Find appropriate name.
37	/// These objects are managed by ASTContext.
38	class ASTRecordLayout {
39	public:
40	struct VBaseInfo {
41	/// The offset to this virtual base in the complete-object layout
42	/// of this class.
43	CharUnits VBaseOffset;
44
45	private:
46	/// Whether this virtual base requires a vtordisp field in the
47	/// Microsoft ABI. These fields are required for certain operations
48	/// in constructors and destructors.
49	bool HasVtorDisp = false;
50
51	public:
52	VBaseInfo() = default;
53	VBaseInfo(CharUnits VBaseOffset, bool hasVtorDisp)
54	: VBaseOffset(VBaseOffset), HasVtorDisp(hasVtorDisp) {}
55
56	bool hasVtorDisp() const { return HasVtorDisp; }
57	};
58
59	using VBaseOffsetsMapTy = llvm::DenseMap<const CXXRecordDecl *, VBaseInfo>;
60
61	private:
62	friend class ASTContext;
63
64	/// Size - Size of record in characters.
65	CharUnits Size;
66
67	/// DataSize - Size of record in characters without tail padding.
68	CharUnits DataSize;
69
70	// Alignment - Alignment of record in characters.
71	CharUnits Alignment;
72
73	// UnadjustedAlignment - Maximum of the alignments of the record members in
74	// characters.
75	CharUnits UnadjustedAlignment;
76
77	/// RequiredAlignment - The required alignment of the object. In the MS-ABI
78	/// the __declspec(align()) trumps #pramga pack and must always be obeyed.
79	CharUnits RequiredAlignment;
80
81	/// FieldOffsets - Array of field offsets in bits.
82	ASTVector<uint64_t> FieldOffsets;
83
84	/// CXXRecordLayoutInfo - Contains C++ specific layout information.
85	struct CXXRecordLayoutInfo {
86	/// NonVirtualSize - The non-virtual size (in chars) of an object, which is
87	/// the size of the object without virtual bases.
88	CharUnits NonVirtualSize;
89
90	/// NonVirtualAlignment - The non-virtual alignment (in chars) of an object,
91	/// which is the alignment of the object without virtual bases.
92	CharUnits NonVirtualAlignment;
93
94	/// SizeOfLargestEmptySubobject - The size of the largest empty subobject
95	/// (either a base or a member). Will be zero if the class doesn't contain
96	/// any empty subobjects.
97	CharUnits SizeOfLargestEmptySubobject;
98
99	/// VBPtrOffset - Virtual base table offset (Microsoft-only).
100	CharUnits VBPtrOffset;
101
102	/// HasOwnVFPtr - Does this class provide a virtual function table
103	/// (vtable in Itanium, vftbl in Microsoft) that is independent from
104	/// its base classes?
105	bool HasOwnVFPtr : 1;
106
107	/// HasVFPtr - Does this class have a vftable that could be extended by
108	/// a derived class. The class may have inherited this pointer from
109	/// a primary base class.
110	bool HasExtendableVFPtr : 1;
111
112	/// EndsWithZeroSizedObject - True if this class contains a zero sized
113	/// member or base or a base with a zero sized member or base.
114	/// Only used for MS-ABI.
115	bool EndsWithZeroSizedObject : 1;
116
117	/// True if this class is zero sized or first base is zero sized or
118	/// has this property. Only used for MS-ABI.
119	bool LeadsWithZeroSizedBase : 1;
120
121	/// PrimaryBase - The primary base info for this record.
122	llvm::PointerIntPair<const CXXRecordDecl *, 1, bool> PrimaryBase;
123
124	/// BaseSharingVBPtr - The base we share vbptr with.
125	const CXXRecordDecl *BaseSharingVBPtr;
126
127	/// FIXME: This should really use a SmallPtrMap, once we have one in LLVM :)
128	using BaseOffsetsMapTy = llvm::DenseMap<const CXXRecordDecl *, CharUnits>;
129
130	/// BaseOffsets - Contains a map from base classes to their offset.
131	BaseOffsetsMapTy BaseOffsets;
132
133	/// VBaseOffsets - Contains a map from vbase classes to their offset.
134	VBaseOffsetsMapTy VBaseOffsets;
135	};
136
137	/// CXXInfo - If the record layout is for a C++ record, this will have
138	/// C++ specific information about the record.
139	CXXRecordLayoutInfo *CXXInfo = nullptr;
140
141	ASTRecordLayout(const ASTContext &Ctx, CharUnits size, CharUnits alignment,
142	CharUnits unadjustedAlignment,
143	CharUnits requiredAlignment, CharUnits datasize,
144	ArrayRef<uint64_t> fieldoffsets);
145
146	using BaseOffsetsMapTy = CXXRecordLayoutInfo::BaseOffsetsMapTy;
147
148	// Constructor for C++ records.
149	ASTRecordLayout(const ASTContext &Ctx,
150	CharUnits size, CharUnits alignment,
151	CharUnits unadjustedAlignment,
152	CharUnits requiredAlignment,
153	bool hasOwnVFPtr, bool hasExtendableVFPtr,
154	CharUnits vbptroffset,
155	CharUnits datasize,
156	ArrayRef<uint64_t> fieldoffsets,
157	CharUnits nonvirtualsize, CharUnits nonvirtualalignment,
158	CharUnits SizeOfLargestEmptySubobject,
159	const CXXRecordDecl *PrimaryBase,
160	bool IsPrimaryBaseVirtual,
161	const CXXRecordDecl *BaseSharingVBPtr,
162	bool EndsWithZeroSizedObject,
163	bool LeadsWithZeroSizedBase,
164	const BaseOffsetsMapTy& BaseOffsets,
165	const VBaseOffsetsMapTy& VBaseOffsets);
166
167	~ASTRecordLayout() = default;
168
169	void Destroy(ASTContext &Ctx);
170
171	public:
172	ASTRecordLayout(const ASTRecordLayout &) = delete;
173	ASTRecordLayout &operator=(const ASTRecordLayout &) = delete;
174
175	/// getAlignment - Get the record alignment in characters.
176	CharUnits getAlignment() const { return Alignment; }
177
178	/// getUnadjustedAlignment - Get the record alignment in characters, before
179	/// alignment adjustement.
180	CharUnits getUnadjustedAlignment() const { return UnadjustedAlignment; }
181
182	/// getSize - Get the record size in characters.
183	CharUnits getSize() const { return Size; }
184
185	/// getFieldCount - Get the number of fields in the layout.
186	unsigned getFieldCount() const { return FieldOffsets.size(); }
187
188	/// getFieldOffset - Get the offset of the given field index, in
189	/// bits.
190	uint64_t getFieldOffset(unsigned FieldNo) const {
191	return FieldOffsets[FieldNo];
192	}
193
194	/// getDataSize() - Get the record data size, which is the record size
195	/// without tail padding, in characters.
196	CharUnits getDataSize() const {
197	return DataSize;
198	}
199
200	/// getNonVirtualSize - Get the non-virtual size (in chars) of an object,
201	/// which is the size of the object without virtual bases.
202	CharUnits getNonVirtualSize() const {
203	(0) . __assert_fail ("CXXInfo && \"Record layout does not have C++ specific info!\"", "/home/seafit/code_projects/clang_source/clang/include/clang/AST/RecordLayout.h", 203, __PRETTY_FUNCTION__))" file_link="../../../../include/assert.h.html#88" macro="true">assert(CXXInfo && "Record layout does not have C++ specific info!");
204
205	return CXXInfo->NonVirtualSize;
206	}
207
208	/// getNonVirtualSize - Get the non-virtual alignment (in chars) of an object,
209	/// which is the alignment of the object without virtual bases.
210	CharUnits getNonVirtualAlignment() const {
211	(0) . __assert_fail ("CXXInfo && \"Record layout does not have C++ specific info!\"", "/home/seafit/code_projects/clang_source/clang/include/clang/AST/RecordLayout.h", 211, __PRETTY_FUNCTION__))" file_link="../../../../include/assert.h.html#88" macro="true">assert(CXXInfo && "Record layout does not have C++ specific info!");
212
213	return CXXInfo->NonVirtualAlignment;
214	}
215
216	/// getPrimaryBase - Get the primary base for this record.
217	const CXXRecordDecl *getPrimaryBase() const {
218	(0) . __assert_fail ("CXXInfo && \"Record layout does not have C++ specific info!\"", "/home/seafit/code_projects/clang_source/clang/include/clang/AST/RecordLayout.h", 218, __PRETTY_FUNCTION__))" file_link="../../../../include/assert.h.html#88" macro="true">assert(CXXInfo && "Record layout does not have C++ specific info!");
219
220	return CXXInfo->PrimaryBase.getPointer();
221	}
222
223	/// isPrimaryBaseVirtual - Get whether the primary base for this record
224	/// is virtual or not.
225	bool isPrimaryBaseVirtual() const {
226	(0) . __assert_fail ("CXXInfo && \"Record layout does not have C++ specific info!\"", "/home/seafit/code_projects/clang_source/clang/include/clang/AST/RecordLayout.h", 226, __PRETTY_FUNCTION__))" file_link="../../../../include/assert.h.html#88" macro="true">assert(CXXInfo && "Record layout does not have C++ specific info!");
227
228	return CXXInfo->PrimaryBase.getInt();
229	}
230
231	/// getBaseClassOffset - Get the offset, in chars, for the given base class.
232	CharUnits getBaseClassOffset(const CXXRecordDecl *Base) const {
233	(0) . __assert_fail ("CXXInfo && \"Record layout does not have C++ specific info!\"", "/home/seafit/code_projects/clang_source/clang/include/clang/AST/RecordLayout.h", 233, __PRETTY_FUNCTION__))" file_link="../../../../include/assert.h.html#88" macro="true">assert(CXXInfo && "Record layout does not have C++ specific info!");
234	(0) . __assert_fail ("CXXInfo->BaseOffsets.count(Base) && \"Did not find base!\"", "/home/seafit/code_projects/clang_source/clang/include/clang/AST/RecordLayout.h", 234, __PRETTY_FUNCTION__))" file_link="../../../../include/assert.h.html#88" macro="true">assert(CXXInfo->BaseOffsets.count(Base) && "Did not find base!");
235
236	return CXXInfo->BaseOffsets[Base];
237	}
238
239	/// getVBaseClassOffset - Get the offset, in chars, for the given base class.
240	CharUnits getVBaseClassOffset(const CXXRecordDecl *VBase) const {
241	(0) . __assert_fail ("CXXInfo && \"Record layout does not have C++ specific info!\"", "/home/seafit/code_projects/clang_source/clang/include/clang/AST/RecordLayout.h", 241, __PRETTY_FUNCTION__))" file_link="../../../../include/assert.h.html#88" macro="true">assert(CXXInfo && "Record layout does not have C++ specific info!");
242	(0) . __assert_fail ("CXXInfo->VBaseOffsets.count(VBase) && \"Did not find base!\"", "/home/seafit/code_projects/clang_source/clang/include/clang/AST/RecordLayout.h", 242, __PRETTY_FUNCTION__))" file_link="../../../../include/assert.h.html#88" macro="true">assert(CXXInfo->VBaseOffsets.count(VBase) && "Did not find base!");
243
244	return CXXInfo->VBaseOffsets[VBase].VBaseOffset;
245	}
246
247	CharUnits getSizeOfLargestEmptySubobject() const {
248	(0) . __assert_fail ("CXXInfo && \"Record layout does not have C++ specific info!\"", "/home/seafit/code_projects/clang_source/clang/include/clang/AST/RecordLayout.h", 248, __PRETTY_FUNCTION__))" file_link="../../../../include/assert.h.html#88" macro="true">assert(CXXInfo && "Record layout does not have C++ specific info!");
249	return CXXInfo->SizeOfLargestEmptySubobject;
250	}
251
252	/// hasOwnVFPtr - Does this class provide its own virtual-function
253	/// table pointer, rather than inheriting one from a primary base
254	/// class? If so, it is at offset zero.
255	///
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
258	/// of the ABI.
259	bool hasOwnVFPtr() const {
260	(0) . __assert_fail ("CXXInfo && \"Record layout does not have C++ specific info!\"", "/home/seafit/code_projects/clang_source/clang/include/clang/AST/RecordLayout.h", 260, __PRETTY_FUNCTION__))" file_link="../../../../include/assert.h.html#88" macro="true">assert(CXXInfo && "Record layout does not have C++ specific info!");
261	return CXXInfo->HasOwnVFPtr;
262	}
263
264	/// hasVFPtr - Does this class have a virtual function table pointer
265	/// that can be extended by a derived class? This is synonymous with
266	/// this class having a VFPtr at offset zero.
267	bool hasExtendableVFPtr() const {
268	(0) . __assert_fail ("CXXInfo && \"Record layout does not have C++ specific info!\"", "/home/seafit/code_projects/clang_source/clang/include/clang/AST/RecordLayout.h", 268, __PRETTY_FUNCTION__))" file_link="../../../../include/assert.h.html#88" macro="true">assert(CXXInfo && "Record layout does not have C++ specific info!");
269	return CXXInfo->HasExtendableVFPtr;
270	}
271
272	/// hasOwnVBPtr - Does this class provide its own virtual-base
273	/// table pointer, rather than inheriting one from a primary base
274	/// class?
275	///
276	/// This implies that the ABI has no primary base class, meaning
277	/// that it has no base classes that are suitable under the conditions
278	/// of the ABI.
279	bool hasOwnVBPtr() const {
280	(0) . __assert_fail ("CXXInfo && \"Record layout does not have C++ specific info!\"", "/home/seafit/code_projects/clang_source/clang/include/clang/AST/RecordLayout.h", 280, __PRETTY_FUNCTION__))" file_link="../../../../include/assert.h.html#88" macro="true">assert(CXXInfo && "Record layout does not have C++ specific info!");
281	return hasVBPtr() && !CXXInfo->BaseSharingVBPtr;
282	}
283
284	/// hasVBPtr - Does this class have a virtual function table pointer.
285	bool hasVBPtr() const {
286	(0) . __assert_fail ("CXXInfo && \"Record layout does not have C++ specific info!\"", "/home/seafit/code_projects/clang_source/clang/include/clang/AST/RecordLayout.h", 286, __PRETTY_FUNCTION__))" file_link="../../../../include/assert.h.html#88" macro="true">assert(CXXInfo && "Record layout does not have C++ specific info!");
287	return !CXXInfo->VBPtrOffset.isNegative();
288	}
289
290	CharUnits getRequiredAlignment() const {
291	return RequiredAlignment;
292	}
293
294	bool endsWithZeroSizedObject() const {
295	return CXXInfo && CXXInfo->EndsWithZeroSizedObject;
296	}
297
298	bool leadsWithZeroSizedBase() const {
299	(0) . __assert_fail ("CXXInfo && \"Record layout does not have C++ specific info!\"", "/home/seafit/code_projects/clang_source/clang/include/clang/AST/RecordLayout.h", 299, __PRETTY_FUNCTION__))" file_link="../../../../include/assert.h.html#88" macro="true">assert(CXXInfo && "Record layout does not have C++ specific info!");
300	return CXXInfo->LeadsWithZeroSizedBase;
301	}
302
303	/// getVBPtrOffset - Get the offset for virtual base table pointer.
304	/// This is only meaningful with the Microsoft ABI.
305	CharUnits getVBPtrOffset() const {
306	(0) . __assert_fail ("CXXInfo && \"Record layout does not have C++ specific info!\"", "/home/seafit/code_projects/clang_source/clang/include/clang/AST/RecordLayout.h", 306, __PRETTY_FUNCTION__))" file_link="../../../../include/assert.h.html#88" macro="true">assert(CXXInfo && "Record layout does not have C++ specific info!");
307	return CXXInfo->VBPtrOffset;
308	}
309
310	const CXXRecordDecl *getBaseSharingVBPtr() const {
311	(0) . __assert_fail ("CXXInfo && \"Record layout does not have C++ specific info!\"", "/home/seafit/code_projects/clang_source/clang/include/clang/AST/RecordLayout.h", 311, __PRETTY_FUNCTION__))" file_link="../../../../include/assert.h.html#88" macro="true">assert(CXXInfo && "Record layout does not have C++ specific info!");
312	return CXXInfo->BaseSharingVBPtr;
313	}
314
315	const VBaseOffsetsMapTy &getVBaseOffsetsMap() const {
316	(0) . __assert_fail ("CXXInfo && \"Record layout does not have C++ specific info!\"", "/home/seafit/code_projects/clang_source/clang/include/clang/AST/RecordLayout.h", 316, __PRETTY_FUNCTION__))" file_link="../../../../include/assert.h.html#88" macro="true">assert(CXXInfo && "Record layout does not have C++ specific info!");
317	return CXXInfo->VBaseOffsets;
318	}
319	};
320
321	} // namespace clang
322
323	#endif // LLVM_CLANG_AST_RECORDLAYOUT_H
324