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 bool
  65 attribute::form_is_block () const
  66 {
  67   return (form == DW_FORM_block1
  68           || form == DW_FORM_block2
  69           || form == DW_FORM_block4
  70           || form == DW_FORM_block
  71           || form == DW_FORM_exprloc);
  72 }
  73
  74 /* See attribute.h.  */
  75
  76 bool
  77 attribute::form_is_section_offset () const
  78 {
  79   return (form == DW_FORM_data4
  80           || form == DW_FORM_data8
  81           || form == DW_FORM_sec_offset);
  82 }
  83
  84 /* See attribute.h.  */
  85
  86 bool
  87 attribute::form_is_constant () const
  88 {
  89   switch (form)
  90     {
  91     case DW_FORM_sdata:
  92     case DW_FORM_udata:
  93     case DW_FORM_data1:
  94     case DW_FORM_data2:
  95     case DW_FORM_data4:
  96     case DW_FORM_data8:
  97     case DW_FORM_implicit_const:
  98       return true;
  99     default:
 100       return false;
 101     }
 102 }
 103
 104 /* DW_ADDR is always stored already as sect_offset; despite for the forms
 105    besides DW_FORM_ref_addr it is stored as cu_offset in the DWARF file.  */
 106
 107 bool
 108 attribute::form_is_ref () const
 109 {
 110   switch (form)
 111     {
 112     case DW_FORM_ref_addr:
 113     case DW_FORM_ref1:
 114     case DW_FORM_ref2:
 115     case DW_FORM_ref4:
 116     case DW_FORM_ref8:
 117     case DW_FORM_ref_udata:
 118     case DW_FORM_GNU_ref_alt:
 119       return true;
 120     default:
 121       return false;
 122     }
 123 }
 124
 125 /* See attribute.h.  */
 126
 127 sect_offset
 128 attribute::get_ref_die_offset () const
 129 {
 130   if (form_is_ref ())
 131     return (sect_offset) DW_UNSND (this);
 132
 133   complaint (_("unsupported die ref attribute form: '%s'"),
 134              dwarf_form_name (form));
 135   return {};
 136 }
 137
 138 /* See attribute.h.  */
 139
 140 LONGEST
 141 attribute::constant_value (int default_value) const
 142 {
 143   if (form == DW_FORM_sdata || form == DW_FORM_implicit_const)
 144     return DW_SND (this);
 145   else if (form == DW_FORM_udata
 146            || form == DW_FORM_data1
 147            || form == DW_FORM_data2
 148            || form == DW_FORM_data4
 149            || form == DW_FORM_data8)
 150     return DW_UNSND (this);
 151   else
 152     {
 153       /* For DW_FORM_data16 see attribute::form_is_constant.  */
 154       complaint (_("Attribute value is not a constant (%s)"),
 155                  dwarf_form_name (form));
 156       return default_value;
 157     }
 158 }