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die.h revision 1.1.1.3 
      1 /* DWARF DIEs
      2 
      3    Copyright (C) 2003-2024 Free Software Foundation, Inc.
      4 
      5    This file is part of GDB.
      6 
      7    This program is free software; you can redistribute it and/or modify
      8    it under the terms of the GNU General Public License as published by
      9    the Free Software Foundation; either version 3 of the License, or
     10    (at your option) any later version.
     11 
     12    This program is distributed in the hope that it will be useful,
     13    but WITHOUT ANY WARRANTY; without even the implied warranty of
     14    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
     15    GNU General Public License for more details.
     16 
     17    You should have received a copy of the GNU General Public License
     18    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
     19 
     20 #ifndef GDB_DWARF2_DIE_H
     21 #define GDB_DWARF2_DIE_H
     22 
     23 #include "complaints.h"
     24 #include "dwarf2/attribute.h"
     25 #include "hashtab.h"
     26 
     27 /* This data structure holds a complete die structure.  */
     28 struct die_info
     29 {
     30   /* Allocate a new die_info on OBSTACK.  NUM_ATTRS is the number of
     31      attributes that are needed.  */
     32   static die_info *allocate (struct obstack *obstack, int num_attrs);
     33 
     34   /* Trivial hash function for die_info: the hash value of a DIE is
     35      its offset in .debug_info for this objfile.  */
     36   static hashval_t hash (const void *item);
     37 
     38   /* Trivial comparison function for die_info structures: two DIEs
     39      are equal if they have the same offset.  */
     40   static int eq (const void *item_lhs, const void *item_rhs);
     41 
     42   /* Dump this DIE and any children to MAX_LEVEL.  They are written to
     43      gdb_stdlog.  Note this is called from the pdie user command in
     44      gdb-gdb.gdb.  */
     45   void dump (int max_level);
     46 
     47   /* Shallowly dump this DIE to gdb_stderr.  */
     48   void error_dump ();
     49 
     50   /* Return the named attribute or NULL if not there, but do not
     51      follow DW_AT_specification, etc.  */
     52   struct attribute *attr (dwarf_attribute name)
     53   {
     54     for (unsigned i = 0; i < num_attrs; ++i)
     55       if (attrs[i].name == name)
     56 	return &attrs[i];
     57     return NULL;
     58   }
     59 
     60   /* Return the address base of the compile unit, which, if exists, is
     61      stored either at the attribute DW_AT_GNU_addr_base, or
     62      DW_AT_addr_base.  */
     63   std::optional<ULONGEST> addr_base ()
     64   {
     65     for (unsigned i = 0; i < num_attrs; ++i)
     66       if (attrs[i].name == DW_AT_addr_base
     67 	   || attrs[i].name == DW_AT_GNU_addr_base)
     68 	{
     69 	  if (attrs[i].form_is_unsigned ())
     70 	    {
     71 	      /* If both exist, just use the first one.  */
     72 	      return attrs[i].as_unsigned ();
     73 	    }
     74 	  complaint (_("address base attribute (offset %s) as wrong form"),
     75 		     sect_offset_str (sect_off));
     76 	}
     77     return std::optional<ULONGEST> ();
     78   }
     79 
     80   /* Return the base address of the compile unit into the .debug_ranges section,
     81      which, if exists, is stored in the DW_AT_GNU_ranges_base attribute.  This
     82      value is only relevant in pre-DWARF 5 split-unit scenarios.  */
     83   ULONGEST gnu_ranges_base ()
     84   {
     85     for (unsigned i = 0; i < num_attrs; ++i)
     86       if (attrs[i].name == DW_AT_GNU_ranges_base)
     87 	{
     88 	  if (attrs[i].form_is_unsigned ())
     89 	    return attrs[i].as_unsigned ();
     90 
     91 	  complaint (_("ranges base attribute (offset %s) has wrong form"),
     92 		     sect_offset_str (sect_off));
     93 	}
     94 
     95     return 0;
     96   }
     97 
     98   /* Return the rnglists base of the compile unit, which, if exists, is stored
     99      in the DW_AT_rnglists_base attribute.  */
    100   ULONGEST rnglists_base ()
    101   {
    102     for (unsigned i = 0; i < num_attrs; ++i)
    103       if (attrs[i].name == DW_AT_rnglists_base)
    104 	{
    105 	  if (attrs[i].form_is_unsigned ())
    106 	    return attrs[i].as_unsigned ();
    107 
    108 	  complaint (_("rnglists base attribute (offset %s) has wrong form"),
    109 		     sect_offset_str (sect_off));
    110 	}
    111 
    112     return 0;
    113   }
    114 
    115   /* DWARF-2 tag for this DIE.  */
    116   ENUM_BITFIELD(dwarf_tag) tag : 16;
    117 
    118   /* Number of attributes */
    119   unsigned char num_attrs;
    120 
    121   /* True if we're presently building the full type name for the
    122      type derived from this DIE.  */
    123   unsigned char building_fullname : 1;
    124 
    125   /* True if this die is in process.  PR 16581.  */
    126   unsigned char in_process : 1;
    127 
    128   /* True if this DIE has children.  */
    129   unsigned char has_children : 1;
    130 
    131   /* Abbrev number */
    132   unsigned int abbrev;
    133 
    134   /* Offset in .debug_info or .debug_types section.  */
    135   sect_offset sect_off;
    136 
    137   /* The dies in a compilation unit form an n-ary tree.  PARENT
    138      points to this die's parent; CHILD points to the first child of
    139      this node; and all the children of a given node are chained
    140      together via their SIBLING fields.  */
    141   struct die_info *child;	/* Its first child, if any.  */
    142   struct die_info *sibling;	/* Its next sibling, if any.  */
    143   struct die_info *parent;	/* Its parent, if any.  */
    144 
    145   /* An array of attributes, with NUM_ATTRS elements.  There may be
    146      zero, but it's not common and zero-sized arrays are not
    147      sufficiently portable C.  */
    148   struct attribute attrs[1];
    149 };
    150 
    151 #endif /* GDB_DWARF2_DIE_H */
    152