1//===-- DIERef.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 LLDB_SOURCE_PLUGINS_SYMBOLFILE_DWARF_DIEREF_H
10#define LLDB_SOURCE_PLUGINS_SYMBOLFILE_DWARF_DIEREF_H
11
12#include "lldb/Core/dwarf.h"
13#include "lldb/Utility/LLDBAssert.h"
14#include <cassert>
15#include <optional>
16
17namespace lldb_private::plugin {
18namespace dwarf {
19/// Identifies a DWARF debug info entry within a given Module. It contains three
20/// "coordinates":
21/// - file_index: identifies the separate stand alone debug info file
22/// that is referred to by the main debug info file. This will be the
23/// index of a DWO file for fission, or the .o file on mac when not
24/// using a dSYM file. If this field is not set, then this references
25/// a DIE inside the original object file.
26/// - section: identifies the section of the debug info entry in the given file:
27/// debug_info or debug_types.
28/// - die_offset: The offset of the debug info entry as an absolute offset from
29/// the beginning of the section specified in the section field.
30class DIERef {
31public:
32 enum Section : uint8_t { DebugInfo, DebugTypes };
33 DIERef(std::optional<uint32_t> file_index, Section section,
34 dw_offset_t die_offset)
35 : m_die_offset(die_offset), m_file_index(file_index.value_or(u: 0)),
36 m_file_index_valid(file_index ? true : false), m_section(section) {
37 assert(this->file_index() == file_index && "File Index is out of range?");
38 }
39
40 explicit DIERef(lldb::user_id_t uid) {
41 m_die_offset = uid & k_die_offset_mask;
42 m_file_index_valid = (uid & k_file_index_valid_bit) != 0;
43 m_file_index = m_file_index_valid
44 ? (uid >> k_die_offset_bit_size) & k_file_index_mask
45 : 0;
46 m_section =
47 (uid & k_section_bit) != 0 ? Section::DebugTypes : Section::DebugInfo;
48 }
49
50 lldb::user_id_t get_id() const {
51 if (m_die_offset == k_die_offset_mask)
52 return LLDB_INVALID_UID;
53
54 return lldb::user_id_t(file_index().value_or(u: 0)) << k_die_offset_bit_size |
55 die_offset() | (m_file_index_valid ? k_file_index_valid_bit : 0) |
56 (section() == Section::DebugTypes ? k_section_bit : 0);
57 }
58
59 std::optional<uint32_t> file_index() const {
60 if (m_file_index_valid)
61 return m_file_index;
62 return std::nullopt;
63 }
64
65 Section section() const { return static_cast<Section>(m_section); }
66
67 dw_offset_t die_offset() const { return m_die_offset; }
68
69 bool operator<(DIERef other) const {
70 if (m_file_index_valid != other.m_file_index_valid)
71 return m_file_index_valid < other.m_file_index_valid;
72 if (m_file_index_valid && (m_file_index != other.m_file_index))
73 return m_file_index < other.m_file_index;
74 if (m_section != other.m_section)
75 return m_section < other.m_section;
76 return m_die_offset < other.m_die_offset;
77 }
78
79 bool operator==(const DIERef &rhs) const {
80 return file_index() == rhs.file_index() && m_section == rhs.m_section &&
81 m_die_offset == rhs.m_die_offset;
82 }
83
84 bool operator!=(const DIERef &rhs) const { return !(*this == rhs); }
85
86 /// Decode a serialized version of this object from data.
87 ///
88 /// \param data
89 /// The decoder object that references the serialized data.
90 ///
91 /// \param offset_ptr
92 /// A pointer that contains the offset from which the data will be decoded
93 /// from that gets updated as data gets decoded.
94 ///
95 /// \return
96 /// Returns a valid DIERef if decoding succeeded, std::nullopt if there was
97 /// unsufficient or invalid values that were decoded.
98 static std::optional<DIERef> Decode(const DataExtractor &data,
99 lldb::offset_t *offset_ptr);
100
101 /// Encode this object into a data encoder object.
102 ///
103 /// This allows this object to be serialized to disk.
104 ///
105 /// \param encoder
106 /// A data encoder object that serialized bytes will be encoded into.
107 ///
108 void Encode(DataEncoder &encoder) const;
109
110 static constexpr uint64_t k_die_offset_bit_size = DW_DIE_OFFSET_MAX_BITSIZE;
111 static constexpr uint64_t k_file_index_bit_size =
112 64 - DW_DIE_OFFSET_MAX_BITSIZE - /* size of control bits */ 2;
113
114 static constexpr uint64_t k_file_index_valid_bit =
115 (1ull << (k_file_index_bit_size + k_die_offset_bit_size));
116 static constexpr uint64_t k_section_bit =
117 (1ull << (k_file_index_bit_size + k_die_offset_bit_size + 1));
118 static constexpr uint64_t
119 k_file_index_mask = (~0ull) >> (64 - k_file_index_bit_size); // 0x3fffff;
120 static constexpr uint64_t k_die_offset_mask = (~0ull) >>
121 (64 - k_die_offset_bit_size);
122
123private:
124 // Allow 2TB of .debug_info/.debug_types offset
125 dw_offset_t m_die_offset : k_die_offset_bit_size;
126 // Used for DWO index or for .o file index on mac
127 dw_offset_t m_file_index : k_file_index_bit_size;
128 // Set to 1 if m_file_index is a DWO number
129 dw_offset_t m_file_index_valid : 1;
130 // Set to 0 for .debug_info 1 for .debug_types,
131 dw_offset_t m_section : 1;
132};
133static_assert(sizeof(DIERef) == 8);
134
135typedef std::vector<DIERef> DIEArray;
136} // namespace dwarf
137} // namespace lldb_private::plugin
138
139namespace llvm {
140template <> struct format_provider<lldb_private::plugin::dwarf::DIERef> {
141 static void format(const lldb_private::plugin::dwarf::DIERef &ref,
142 raw_ostream &OS, StringRef Style);
143};
144} // namespace llvm
145
146#endif // LLDB_SOURCE_PLUGINS_SYMBOLFILE_DWARF_DIEREF_H
147

source code of lldb/source/Plugins/SymbolFile/DWARF/DIERef.h