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           || form == DW_FORM_loclistx);
  83 }
  84
  85 /* See attribute.h.  */
  86
  87 bool
  88 attribute::form_is_constant () const
  89 {
  90   switch (form)
  91     {
  92     case DW_FORM_sdata:
  93     case DW_FORM_udata:
  94     case DW_FORM_data1:
  95     case DW_FORM_data2:
  96     case DW_FORM_data4:
  97     case DW_FORM_data8:
  98     case DW_FORM_implicit_const:
  99       return true;
 100     default:
 101       return false;
 102     }
 103 }
 104
 105 /* DW_ADDR is always stored already as sect_offset; despite for the forms
 106    besides DW_FORM_ref_addr it is stored as cu_offset in the DWARF file.  */
 107
 108 bool
 109 attribute::form_is_ref () const
 110 {
 111   switch (form)
 112     {
 113     case DW_FORM_ref_addr:
 114     case DW_FORM_ref1:
 115     case DW_FORM_ref2:
 116     case DW_FORM_ref4:
 117     case DW_FORM_ref8:
 118     case DW_FORM_ref_udata:
 119     case DW_FORM_GNU_ref_alt:
 120       return true;
 121     default:
 122       return false;
 123     }
 124 }
 125
 126 /* See attribute.h.  */
 127
 128 sect_offset
 129 attribute::get_ref_die_offset () const
 130 {
 131   if (form_is_ref ())
 132     return (sect_offset) DW_UNSND (this);
 133
 134   complaint (_("unsupported die ref attribute form: '%s'"),
 135              dwarf_form_name (form));
 136   return {};
 137 }
 138
 139 /* See attribute.h.  */
 140
 141 LONGEST
 142 attribute::constant_value (int default_value) const
 143 {
 144   if (form == DW_FORM_sdata || form == DW_FORM_implicit_const)
 145     return DW_SND (this);
 146   else if (form == DW_FORM_udata
 147            || form == DW_FORM_data1
 148            || form == DW_FORM_data2
 149            || form == DW_FORM_data4
 150            || form == DW_FORM_data8)
 151     return DW_UNSND (this);
 152   else
 153     {
 154       /* For DW_FORM_data16 see attribute::form_is_constant.  */
 155       complaint (_("Attribute value is not a constant (%s)"),
 156                  dwarf_form_name (form));
 157       return default_value;
 158     }
 159 }