1//===- DWARFAbbreviationDeclaration.h ---------------------------*- 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#ifndef LLVM_DEBUGINFO_DWARF_DWARFABBREVIATIONDECLARATION_H
10#define LLVM_DEBUGINFO_DWARF_DWARFABBREVIATIONDECLARATION_H
11
12#include "llvm/ADT/Optional.h"
13#include "llvm/ADT/SmallVector.h"
14#include "llvm/ADT/iterator_range.h"
15#include "llvm/BinaryFormat/Dwarf.h"
16#include "llvm/Support/DataExtractor.h"
17#include <cassert>
18#include <cstddef>
19#include <cstdint>
20
21namespace llvm {
22
23class DWARFFormValue;
24class DWARFUnit;
25class raw_ostream;
26
27class DWARFAbbreviationDeclaration {
28public:
29 struct AttributeSpec {
30 AttributeSpec(dwarf::Attribute A, dwarf::Form F, int64_t Value)
31 : Attr(A), Form(F), Value(Value) {
32 assert(isImplicitConst());
33 }
34 AttributeSpec(dwarf::Attribute A, dwarf::Form F, Optional<uint8_t> ByteSize)
35 : Attr(A), Form(F) {
36 assert(!isImplicitConst());
37 this->ByteSize.HasByteSize = ByteSize.hasValue();
38 if (this->ByteSize.HasByteSize)
39 this->ByteSize.ByteSize = *ByteSize;
40 }
41
42 dwarf::Attribute Attr;
43 dwarf::Form Form;
44
45 private:
46 /// The following field is used for ByteSize for non-implicit_const
47 /// attributes and as value for implicit_const ones, indicated by
48 /// Form == DW_FORM_implicit_const.
49 /// The following cases are distinguished:
50 /// * Form != DW_FORM_implicit_const and HasByteSize is true:
51 /// ByteSize contains the fixed size in bytes for the Form in this
52 /// object.
53 /// * Form != DW_FORM_implicit_const and HasByteSize is false:
54 /// byte size of Form either varies according to the DWARFUnit
55 /// that it is contained in or the value size varies and must be
56 /// decoded from the debug information in order to determine its size.
57 /// * Form == DW_FORM_implicit_const:
58 /// Value contains value for the implicit_const attribute.
59 struct ByteSizeStorage {
60 bool HasByteSize;
61 uint8_t ByteSize;
62 };
63 union {
64 ByteSizeStorage ByteSize;
65 int64_t Value;
66 };
67
68 public:
69 bool isImplicitConst() const {
70 return Form == dwarf::DW_FORM_implicit_const;
71 }
72
73 int64_t getImplicitConstValue() const {
74 assert(isImplicitConst());
75 return Value;
76 }
77
78 /// Get the fixed byte size of this Form if possible. This function might
79 /// use the DWARFUnit to calculate the size of the Form, like for
80 /// DW_AT_address and DW_AT_ref_addr, so this isn't just an accessor for
81 /// the ByteSize member.
82 Optional<int64_t> getByteSize(const DWARFUnit &U) const;
83 };
84 using AttributeSpecVector = SmallVector<AttributeSpec, 8>;
85
86 DWARFAbbreviationDeclaration();
87
88 uint32_t getCode() const { return Code; }
89 uint8_t getCodeByteSize() const { return CodeByteSize; }
90 dwarf::Tag getTag() const { return Tag; }
91 bool hasChildren() const { return HasChildren; }
92
93 using attr_iterator_range =
94 iterator_range<AttributeSpecVector::const_iterator>;
95
96 attr_iterator_range attributes() const {
97 return attr_iterator_range(AttributeSpecs.begin(), AttributeSpecs.end());
98 }
99
100 dwarf::Form getFormByIndex(uint32_t idx) const {
101 assert(idx < AttributeSpecs.size());
102 return AttributeSpecs[idx].Form;
103 }
104
105 size_t getNumAttributes() const {
106 return AttributeSpecs.size();
107 }
108
109 dwarf::Attribute getAttrByIndex(uint32_t idx) const {
110 assert(idx < AttributeSpecs.size());
111 return AttributeSpecs[idx].Attr;
112 }
113
114 bool getAttrIsImplicitConstByIndex(uint32_t idx) const {
115 assert(idx < AttributeSpecs.size());
116 return AttributeSpecs[idx].isImplicitConst();
117 }
118
119 int64_t getAttrImplicitConstValueByIndex(uint32_t idx) const {
120 assert(idx < AttributeSpecs.size());
121 return AttributeSpecs[idx].getImplicitConstValue();
122 }
123
124 /// Get the index of the specified attribute.
125 ///
126 /// Searches the this abbreviation declaration for the index of the specified
127 /// attribute.
128 ///
129 /// \param attr DWARF attribute to search for.
130 /// \returns Optional index of the attribute if found, None otherwise.
131 Optional<uint32_t> findAttributeIndex(dwarf::Attribute attr) const;
132
133 /// Extract a DWARF form value from a DIE specified by DIE offset.
134 ///
135 /// Extract an attribute value for a DWARFUnit given the DIE offset and the
136 /// attribute.
137 ///
138 /// \param DIEOffset the DIE offset that points to the ULEB128 abbreviation
139 /// code in the .debug_info data.
140 /// \param Attr DWARF attribute to search for.
141 /// \param U the DWARFUnit the contains the DIE.
142 /// \returns Optional DWARF form value if the attribute was extracted.
143 Optional<DWARFFormValue> getAttributeValue(const uint64_t DIEOffset,
144 const dwarf::Attribute Attr,
145 const DWARFUnit &U) const;
146
147 bool extract(DataExtractor Data, uint64_t* OffsetPtr);
148 void dump(raw_ostream &OS) const;
149
150 // Return an optional byte size of all attribute data in this abbreviation
151 // if a constant byte size can be calculated given a DWARFUnit. This allows
152 // DWARF parsing to be faster as many DWARF DIEs have a fixed byte size.
153 Optional<size_t> getFixedAttributesByteSize(const DWARFUnit &U) const;
154
155private:
156 void clear();
157
158 /// A helper structure that can quickly determine the size in bytes of an
159 /// abbreviation declaration.
160 struct FixedSizeInfo {
161 /// The fixed byte size for fixed size forms.
162 uint16_t NumBytes = 0;
163 /// Number of DW_FORM_address forms in this abbrevation declaration.
164 uint8_t NumAddrs = 0;
165 /// Number of DW_FORM_ref_addr forms in this abbrevation declaration.
166 uint8_t NumRefAddrs = 0;
167 /// Number of 4 byte in DWARF32 and 8 byte in DWARF64 forms.
168 uint8_t NumDwarfOffsets = 0;
169
170 FixedSizeInfo() = default;
171
172 /// Calculate the fixed size in bytes given a DWARFUnit.
173 ///
174 /// \param U the DWARFUnit to use when determing the byte size.
175 /// \returns the size in bytes for all attribute data in this abbreviation.
176 /// The returned size does not include bytes for the ULEB128 abbreviation
177 /// code
178 size_t getByteSize(const DWARFUnit &U) const;
179 };
180
181 uint32_t Code;
182 dwarf::Tag Tag;
183 uint8_t CodeByteSize;
184 bool HasChildren;
185 AttributeSpecVector AttributeSpecs;
186 /// If this abbreviation has a fixed byte size then FixedAttributeSize member
187 /// variable below will have a value.
188 Optional<FixedSizeInfo> FixedAttributeSize;
189};
190
191} // end namespace llvm
192
193#endif // LLVM_DEBUGINFO_DWARF_DWARFABBREVIATIONDECLARATION_H
194