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

   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