1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
|
//===--- Descriptor.h - Types for the constexpr VM --------------*- C++ -*-===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// Defines descriptors which characterise allocations.
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_CLANG_AST_INTERP_DESCRIPTOR_H
#define LLVM_CLANG_AST_INTERP_DESCRIPTOR_H
#include "clang/AST/Decl.h"
#include "clang/AST/Expr.h"
namespace clang {
namespace interp {
class Block;
class Record;
struct Descriptor;
enum PrimType : unsigned;
using DeclTy = llvm::PointerUnion<const Decl *, const Expr *>;
/// Invoked whenever a block is created. The constructor method fills in the
/// inline descriptors of all fields and array elements. It also initializes
/// all the fields which contain non-trivial types.
using BlockCtorFn = void (*)(Block *Storage, char *FieldPtr, bool IsConst,
bool IsMutable, bool IsActive,
Descriptor *FieldDesc);
/// Invoked when a block is destroyed. Invokes the destructors of all
/// non-trivial nested fields of arrays and records.
using BlockDtorFn = void (*)(Block *Storage, char *FieldPtr,
Descriptor *FieldDesc);
/// Invoked when a block with pointers referencing it goes out of scope. Such
/// blocks are persisted: the move function copies all inline descriptors and
/// non-trivial fields, as existing pointers might need to reference those
/// descriptors. Data is not copied since it cannot be legally read.
using BlockMoveFn = void (*)(Block *Storage, char *SrcFieldPtr,
char *DstFieldPtr, Descriptor *FieldDesc);
/// Object size as used by the interpreter.
using InterpSize = unsigned;
/// Describes a memory block created by an allocation site.
struct Descriptor {
private:
/// Original declaration, used to emit the error message.
const DeclTy Source;
/// Size of an element, in host bytes.
const InterpSize ElemSize;
/// Size of the storage, in host bytes.
const InterpSize Size;
/// Size of the allocation (storage + metadata), in host bytes.
const InterpSize AllocSize;
/// Value to denote arrays of unknown size.
static constexpr unsigned UnknownSizeMark = (unsigned)-1;
public:
/// Token to denote structures of unknown size.
struct UnknownSize {};
/// Pointer to the record, if block contains records.
Record *const ElemRecord = nullptr;
/// Descriptor of the array element.
Descriptor *const ElemDesc = nullptr;
/// Flag indicating if the block is mutable.
const bool IsConst = false;
/// Flag indicating if a field is mutable.
const bool IsMutable = false;
/// Flag indicating if the block is a temporary.
const bool IsTemporary = false;
/// Flag indicating if the block is an array.
const bool IsArray = false;
/// Storage management methods.
const BlockCtorFn CtorFn = nullptr;
const BlockDtorFn DtorFn = nullptr;
const BlockMoveFn MoveFn = nullptr;
/// Allocates a descriptor for a primitive.
Descriptor(const DeclTy &D, PrimType Type, bool IsConst, bool IsTemporary,
bool IsMutable);
/// Allocates a descriptor for an array of primitives.
Descriptor(const DeclTy &D, PrimType Type, size_t NumElems, bool IsConst,
bool IsTemporary, bool IsMutable);
/// Allocates a descriptor for an array of primitives of unknown size.
Descriptor(const DeclTy &D, PrimType Type, bool IsTemporary, UnknownSize);
/// Allocates a descriptor for an array of composites.
Descriptor(const DeclTy &D, Descriptor *Elem, unsigned NumElems, bool IsConst,
bool IsTemporary, bool IsMutable);
/// Allocates a descriptor for an array of composites of unknown size.
Descriptor(const DeclTy &D, Descriptor *Elem, bool IsTemporary, UnknownSize);
/// Allocates a descriptor for a record.
Descriptor(const DeclTy &D, Record *R, bool IsConst, bool IsTemporary,
bool IsMutable);
QualType getType() const;
SourceLocation getLocation() const;
const Decl *asDecl() const { return Source.dyn_cast<const Decl *>(); }
const Expr *asExpr() const { return Source.dyn_cast<const Expr *>(); }
const ValueDecl *asValueDecl() const {
return dyn_cast_or_null<ValueDecl>(asDecl());
}
const FieldDecl *asFieldDecl() const {
return dyn_cast_or_null<FieldDecl>(asDecl());
}
const RecordDecl *asRecordDecl() const {
return dyn_cast_or_null<RecordDecl>(asDecl());
}
/// Returns the size of the object without metadata.
unsigned getSize() const {
assert(!isUnknownSizeArray() && "Array of unknown size");
return Size;
}
/// Returns the allocated size, including metadata.
unsigned getAllocSize() const { return AllocSize; }
/// returns the size of an element when the structure is viewed as an array.
unsigned getElemSize() const { return ElemSize; }
/// Returns the number of elements stored in the block.
unsigned getNumElems() const {
return Size == UnknownSizeMark ? 0 : (getSize() / getElemSize());
}
/// Checks if the descriptor is of an array of primitives.
bool isPrimitiveArray() const { return IsArray && !ElemDesc; }
/// Checks if the descriptor is of an array of zero size.
bool isZeroSizeArray() const { return Size == 0; }
/// Checks if the descriptor is of an array of unknown size.
bool isUnknownSizeArray() const { return Size == UnknownSizeMark; }
/// Checks if the descriptor is of a primitive.
bool isPrimitive() const { return !IsArray && !ElemRecord; }
/// Checks if the descriptor is of an array.
bool isArray() const { return IsArray; }
};
/// Inline descriptor embedded in structures and arrays.
///
/// Such descriptors precede all composite array elements and structure fields.
/// If the base of a pointer is not zero, the base points to the end of this
/// structure. The offset field is used to traverse the pointer chain up
/// to the root structure which allocated the object.
struct InlineDescriptor {
/// Offset inside the structure/array.
unsigned Offset;
/// Flag indicating if the storage is constant or not.
/// Relevant for primitive fields.
unsigned IsConst : 1;
/// For primitive fields, it indicates if the field was initialized.
/// Primitive fields in static storage are always initialized.
/// Arrays are always initialized, even though their elements might not be.
/// Base classes are initialized after the constructor is invoked.
unsigned IsInitialized : 1;
/// Flag indicating if the field is an embedded base class.
unsigned IsBase : 1;
/// Flag indicating if the field is the active member of a union.
unsigned IsActive : 1;
/// Flag indicating if the field is mutable (if in a record).
unsigned IsMutable : 1;
Descriptor *Desc;
};
/// Bitfield tracking the initialisation status of elements of primitive arrays.
/// A pointer to this is embedded at the end of all primitive arrays.
/// If the map was not yet created and nothing was initialized, the pointer to
/// this structure is 0. If the object was fully initialized, the pointer is -1.
struct InitMap {
private:
/// Type packing bits.
using T = uint64_t;
/// Bits stored in a single field.
static constexpr uint64_t PER_FIELD = sizeof(T) * CHAR_BIT;
/// Initializes the map with no fields set.
InitMap(unsigned N);
/// Returns a pointer to storage.
T *data();
public:
/// Initializes an element. Returns true when object if fully initialized.
bool initialize(unsigned I);
/// Checks if an element was initialized.
bool isInitialized(unsigned I);
/// Allocates a map holding N elements.
static InitMap *allocate(unsigned N);
private:
/// Number of fields initialized.
unsigned UninitFields;
};
} // namespace interp
} // namespace clang
#endif
|
