gdb/dwarf2/attribute.c

   1 /* DWARF attributes
   2
   3    Copyright (C) 1994-2020 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 #include "defs.h"
  28 #include "dwarf2/attribute.h"
  29 #include "dwarf2/stringify.h"
  30 #include "complaints.h"
  31
  32 /* See attribute.h.  */
  33
  34 CORE_ADDR
  35 attribute::value_as_address () const
  36 {
  37   CORE_ADDR addr;
  38
  39   if (form != DW_FORM_addr && form != DW_FORM_addrx
  40       && form != DW_FORM_GNU_addr_index)
  41     {
  42       /* Aside from a few clearly defined exceptions, attributes that
  43          contain an address must always be in DW_FORM_addr form.
  44          Unfortunately, some compilers happen to be violating this
  45          requirement by encoding addresses using other forms, such
  46          as DW_FORM_data4 for example.  For those broken compilers,
  47          we try to do our best, without any guarantee of success,
  48          to interpret the address correctly.  It would also be nice
  49          to generate a complaint, but that would require us to maintain
  50          a list of legitimate cases where a non-address form is allowed,
  51          as well as update callers to pass in at least the CU's DWARF
  52          version.  This is more overhead than what we're willing to
  53          expand for a pretty rare case.  */
  54       addr = DW_UNSND (this);
  55     }
  56   else
  57     addr = DW_ADDR (this);
  58
  59   return addr;
  60 }
  61
  62 /* See attribute.h.  */
  63
  64 const char *
  65 attribute::value_as_string () const
  66 {
  67   if (form == DW_FORM_strp || form == DW_FORM_line_strp
  68       || form == DW_FORM_string
  69       || form == DW_FORM_strx
  70       || form == DW_FORM_strx1
  71       || form == DW_FORM_strx2
  72       || form == DW_FORM_strx3
  73       || form == DW_FORM_strx4
  74       || form == DW_FORM_GNU_str_index
  75       || form == DW_FORM_GNU_strp_alt)
  76     return DW_STRING (this);
  77   return nullptr;
  78 }
  79
  80 /* See attribute.h.  */
  81
  82 bool
  83 attribute::form_is_block () const
  84 {
  85   return (form == DW_FORM_block1
  86           || form == DW_FORM_block2
  87           || form == DW_FORM_block4
  88           || form == DW_FORM_block
  89           || form == DW_FORM_exprloc);
  90 }
  91
  92 /* See attribute.h.  */
  93
  94 bool
  95 attribute::form_is_section_offset () const
  96 {
  97   return (form == DW_FORM_data4
  98           || form == DW_FORM_data8
  99           || form == DW_FORM_sec_offset
 100           || form == DW_FORM_loclistx);
 101 }
 102
 103 /* See attribute.h.  */
 104
 105 bool
 106 attribute::form_is_constant () const
 107 {
 108   switch (form)
 109     {
 110     case DW_FORM_sdata:
 111     case DW_FORM_udata:
 112     case DW_FORM_data1:
 113     case DW_FORM_data2:
 114     case DW_FORM_data4:
 115     case DW_FORM_data8:
 116     case DW_FORM_implicit_const:
 117       return true;
 118     default:
 119       return false;
 120     }
 121 }
 122
 123 /* DW_ADDR is always stored already as sect_offset; despite for the forms
 124    besides DW_FORM_ref_addr it is stored as cu_offset in the DWARF file.  */
 125
 126 bool
 127 attribute::form_is_ref () const
 128 {
 129   switch (form)
 130     {
 131     case DW_FORM_ref_addr:
 132     case DW_FORM_ref1:
 133     case DW_FORM_ref2:
 134     case DW_FORM_ref4:
 135     case DW_FORM_ref8:
 136     case DW_FORM_ref_udata:
 137     case DW_FORM_GNU_ref_alt:
 138       return true;
 139     default:
 140       return false;
 141     }
 142 }
 143
 144 /* See attribute.h.  */
 145
 146 sect_offset
 147 attribute::get_ref_die_offset () const
 148 {
 149   if (form_is_ref ())
 150     return (sect_offset) DW_UNSND (this);
 151
 152   complaint (_("unsupported die ref attribute form: '%s'"),
 153              dwarf_form_name (form));
 154   return {};
 155 }
 156
 157 /* See attribute.h.  */
 158
 159 LONGEST
 160 attribute::constant_value (int default_value) const
 161 {
 162   if (form == DW_FORM_sdata || form == DW_FORM_implicit_const)
 163     return DW_SND (this);
 164   else if (form == DW_FORM_udata
 165            || form == DW_FORM_data1
 166            || form == DW_FORM_data2
 167            || form == DW_FORM_data4
 168            || form == DW_FORM_data8)
 169     return DW_UNSND (this);
 170   else
 171     {
 172       /* For DW_FORM_data16 see attribute::form_is_constant.  */
 173       complaint (_("Attribute value is not a constant (%s)"),
 174                  dwarf_form_name (form));
 175       return default_value;
 176     }
 177 }