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 17 namespace lldb_private::plugin { 18 namespace 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. 30 class DIERef { 31 public: 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(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(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); 122 123 private: 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 }; 133 static_assert(sizeof(DIERef) == 8); 134 135 typedef std::vector<DIERef> DIEArray; 136 } // namespace dwarf 137 } // namespace lldb_private::plugin 138 139 namespace llvm { 140 template <> 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