1 /* DWARF 2 abbreviations
2
3 Copyright (C) 1994-2021 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/read.h"
29 #include "dwarf2/abbrev.h"
30 #include "dwarf2/leb.h"
31 #include "bfd.h"
32
33 /* Hash function for an abbrev. */
34
35 static hashval_t
hash_abbrev(const void * item)36 hash_abbrev (const void *item)
37 {
38 const struct abbrev_info *info = (const struct abbrev_info *) item;
39 /* Warning: if you change this next line, you must also update the
40 other code in this class using the _with_hash functions. */
41 return info->number;
42 }
43
44 /* Comparison function for abbrevs. */
45
46 static int
eq_abbrev(const void * lhs,const void * rhs)47 eq_abbrev (const void *lhs, const void *rhs)
48 {
49 const struct abbrev_info *l_info = (const struct abbrev_info *) lhs;
50 const struct abbrev_info *r_info = (const struct abbrev_info *) rhs;
51 return l_info->number == r_info->number;
52 }
53
54 /* Abbreviation tables.
55
56 In DWARF version 2, the description of the debugging information is
57 stored in a separate .debug_abbrev section. Before we read any
58 dies from a section we read in all abbreviations and install them
59 in a hash table. */
60
abbrev_table(sect_offset off)61 abbrev_table::abbrev_table (sect_offset off)
62 : sect_off (off),
63 m_abbrevs (htab_create_alloc (20, hash_abbrev, eq_abbrev,
64 nullptr, xcalloc, xfree))
65 {
66 }
67
68 /* Add an abbreviation to the table. */
69
70 void
add_abbrev(struct abbrev_info * abbrev)71 abbrev_table::add_abbrev (struct abbrev_info *abbrev)
72 {
73 void **slot = htab_find_slot_with_hash (m_abbrevs.get (), abbrev,
74 abbrev->number, INSERT);
75 *slot = abbrev;
76 }
77
78 /* Read in an abbrev table. */
79
80 abbrev_table_up
read(struct dwarf2_section_info * section,sect_offset sect_off)81 abbrev_table::read (struct dwarf2_section_info *section,
82 sect_offset sect_off)
83 {
84 bfd *abfd = section->get_bfd_owner ();
85 const gdb_byte *abbrev_ptr;
86 struct abbrev_info *cur_abbrev;
87
88 abbrev_table_up abbrev_table (new struct abbrev_table (sect_off));
89 struct obstack *obstack = &abbrev_table->m_abbrev_obstack;
90
91 /* Caller must ensure this. */
92 gdb_assert (section->readin);
93 abbrev_ptr = section->buffer + to_underlying (sect_off);
94
95 while (true)
96 {
97 unsigned int bytes_read;
98 /* Loop until we reach an abbrev number of 0. */
99 unsigned int abbrev_number = read_unsigned_leb128 (abfd, abbrev_ptr,
100 &bytes_read);
101 if (abbrev_number == 0)
102 break;
103 abbrev_ptr += bytes_read;
104
105 /* Start without any attrs. */
106 obstack_blank (obstack, offsetof (abbrev_info, attrs));
107 cur_abbrev = (struct abbrev_info *) obstack_base (obstack);
108
109 /* Read in abbrev header. */
110 cur_abbrev->number = abbrev_number;
111 cur_abbrev->tag
112 = (enum dwarf_tag) read_unsigned_leb128 (abfd, abbrev_ptr,
113 &bytes_read);
114 abbrev_ptr += bytes_read;
115 cur_abbrev->has_children = read_1_byte (abfd, abbrev_ptr);
116 abbrev_ptr += 1;
117
118 /* Now read in declarations. */
119 int num_attrs = 0;
120 for (;;)
121 {
122 struct attr_abbrev cur_attr;
123
124 cur_attr.name
125 = (enum dwarf_attribute) read_unsigned_leb128 (abfd, abbrev_ptr,
126 &bytes_read);
127 abbrev_ptr += bytes_read;
128 cur_attr.form
129 = (enum dwarf_form) read_unsigned_leb128 (abfd, abbrev_ptr,
130 &bytes_read);
131 abbrev_ptr += bytes_read;
132 if (cur_attr.form == DW_FORM_implicit_const)
133 {
134 cur_attr.implicit_const = read_signed_leb128 (abfd, abbrev_ptr,
135 &bytes_read);
136 abbrev_ptr += bytes_read;
137 }
138 else
139 cur_attr.implicit_const = -1;
140
141 if (cur_attr.name == 0)
142 break;
143
144 ++num_attrs;
145 obstack_grow (obstack, &cur_attr, sizeof (cur_attr));
146 }
147
148 cur_abbrev = (struct abbrev_info *) obstack_finish (obstack);
149 cur_abbrev->num_attrs = num_attrs;
150 abbrev_table->add_abbrev (cur_abbrev);
151 }
152
153 return abbrev_table;
154 }
155