gdb/dwarf2/abbrev.h

   1 /* DWARF abbrev table
   2
   3    Copyright (C) 1994-2024 Free Software Foundation, Inc.
   4
   5    Adapted by Gary Funck (gary@intrepid.com), Intrepid Technology,
   6    Inc.  with support from Florida State University (under contract
   7    with the Ada Joint Program Office), and Silicon Graphics, Inc.
   8    Initial contribution by Brent Benson, Harris Computer Systems, Inc.,
   9    based on Fred Fish's (Cygnus Support) implementation of DWARF 1
  10    support.
  11
  12    This file is part of GDB.
  13
  14    This program is free software; you can redistribute it and/or modify
  15    it under the terms of the GNU General Public License as published by
  16    the Free Software Foundation; either version 3 of the License, or
  17    (at your option) any later version.
  18
  19    This program is distributed in the hope that it will be useful,
  20    but WITHOUT ANY WARRANTY; without even the implied warranty of
  21    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  22    GNU General Public License for more details.
  23
  24    You should have received a copy of the GNU General Public License
  25    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
  26
  27 #ifndef GDB_DWARF2_ABBREV_H
  28 #define GDB_DWARF2_ABBREV_H
  29
  30 #include "dwarf2.h"
  31 #include "gdbsupport/gdb_obstack.h"
  32 #include "gdbsupport/unordered_set.h"
  33 #include "types.h"
  34
  35 struct attr_abbrev
  36 {
  37   ENUM_BITFIELD(dwarf_attribute) name : 16;
  38   ENUM_BITFIELD(dwarf_form) form : 16;
  39
  40   /* It is valid only if FORM is DW_FORM_implicit_const.  */
  41   LONGEST implicit_const;
  42 };
  43
  44 /* This data structure holds the information of an abbrev.  */
  45 struct abbrev_info
  46 {
  47   /* Number identifying abbrev.  */
  48   unsigned int number;
  49   /* DWARF tag.  */
  50   ENUM_BITFIELD (dwarf_tag) tag : 16;
  51   /* True if the DIE has children.  */
  52   bool has_children;
  53   bool interesting;
  54   unsigned short size_if_constant;
  55   unsigned short sibling_offset;
  56   /* Number of attributes.  */
  57   unsigned short num_attrs;
  58   /* An array of attribute descriptions, allocated using the struct
  59      hack.  */
  60   struct attr_abbrev attrs[1];
  61 };
  62
  63 struct abbrev_table;
  64 typedef std::unique_ptr<struct abbrev_table> abbrev_table_up;
  65
  66 /* Top level data structure to contain an abbreviation table.
  67
  68    In DWARF version 2, the description of the debugging information is
  69    stored in a separate .debug_abbrev section.  Before we read any
  70    dies from a section we read in all abbreviations and install them
  71    in a hash table.  */
  72
  73 struct abbrev_table
  74 {
  75   /* Read an abbrev table from the indicated section, at the given
  76      offset.  The caller is responsible for ensuring that the section
  77      has already been read.  */
  78
  79   static abbrev_table_up read (struct dwarf2_section_info *section,
  80                                sect_offset sect_off);
  81
  82   /* Look up an abbrev in the table.
  83      Returns NULL if the abbrev is not found.  */
  84
  85   const abbrev_info *lookup_abbrev (unsigned int abbrev_number) const
  86   {
  87     if (auto iter = m_abbrevs.find (abbrev_number);
  88         iter != m_abbrevs.end ())
  89       return *iter;
  90
  91     return nullptr;
  92   }
  93
  94   /* Where the abbrev table came from.
  95      This is used as a sanity check when the table is used.  */
  96   const sect_offset sect_off;
  97
  98   struct dwarf2_section_info *section;
  99
 100 private:
 101
 102   abbrev_table (sect_offset off, struct dwarf2_section_info *sect)
 103     : sect_off (off),
 104       section (sect)
 105   {}
 106
 107   DISABLE_COPY_AND_ASSIGN (abbrev_table);
 108
 109   /* Add an abbreviation to the table.  */
 110   void add_abbrev (const abbrev_info *abbrev)
 111   { m_abbrevs.emplace (abbrev); }
 112
 113   struct abbrev_info_number_eq
 114   {
 115     using is_transparent = void;
 116
 117     bool operator() (unsigned int number,
 118                      const abbrev_info *abbrev) const noexcept
 119     { return number == abbrev->number; }
 120
 121     bool operator() (const abbrev_info *lhs,
 122                      const abbrev_info *rhs) const noexcept
 123     { return (*this) (lhs->number, rhs); }
 124   };
 125
 126   struct abbrev_info_number_hash
 127   {
 128     using is_transparent = void;
 129
 130     std::size_t operator() (unsigned int number) const noexcept
 131     { return std::hash<unsigned int> () (number); }
 132
 133     std::size_t operator() (const abbrev_info *abbrev) const noexcept
 134     { return (*this) (abbrev->number); }
 135
 136   };
 137
 138   /* Hash table of abbrev, identified by their number.  */
 139   gdb::unordered_set<const abbrev_info *,
 140                      abbrev_info_number_hash,
 141                      abbrev_info_number_eq>
 142     m_abbrevs;
 143
 144   /* Storage for the abbrev table.  */
 145   auto_obstack m_abbrev_obstack;
 146 };
 147
 148 #endif /* GDB_DWARF2_ABBREV_H */