1 /* DWARF 2 abbreviations 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/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 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 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 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 /* Allocate space for a struct abbrev_info object in ABBREV_TABLE. */ 69 70 struct abbrev_info * 71 abbrev_table::alloc_abbrev () 72 { 73 struct abbrev_info *abbrev; 74 75 abbrev = XOBNEW (&m_abbrev_obstack, struct abbrev_info); 76 memset (abbrev, 0, sizeof (struct abbrev_info)); 77 78 return abbrev; 79 } 80 81 /* Add an abbreviation to the table. */ 82 83 void 84 abbrev_table::add_abbrev (struct abbrev_info *abbrev) 85 { 86 void **slot = htab_find_slot_with_hash (m_abbrevs.get (), abbrev, 87 abbrev->number, INSERT); 88 *slot = abbrev; 89 } 90 91 /* Read in an abbrev table. */ 92 93 abbrev_table_up 94 abbrev_table::read (struct objfile *objfile, 95 struct dwarf2_section_info *section, 96 sect_offset sect_off) 97 { 98 bfd *abfd = section->get_bfd_owner (); 99 const gdb_byte *abbrev_ptr; 100 struct abbrev_info *cur_abbrev; 101 unsigned int abbrev_number, bytes_read, abbrev_name; 102 unsigned int abbrev_form; 103 std::vector<struct attr_abbrev> cur_attrs; 104 105 abbrev_table_up abbrev_table (new struct abbrev_table (sect_off)); 106 107 section->read (objfile); 108 abbrev_ptr = section->buffer + to_underlying (sect_off); 109 abbrev_number = read_unsigned_leb128 (abfd, abbrev_ptr, &bytes_read); 110 abbrev_ptr += bytes_read; 111 112 /* Loop until we reach an abbrev number of 0. */ 113 while (abbrev_number) 114 { 115 cur_attrs.clear (); 116 cur_abbrev = abbrev_table->alloc_abbrev (); 117 118 /* read in abbrev header */ 119 cur_abbrev->number = abbrev_number; 120 cur_abbrev->tag 121 = (enum dwarf_tag) read_unsigned_leb128 (abfd, abbrev_ptr, &bytes_read); 122 abbrev_ptr += bytes_read; 123 cur_abbrev->has_children = read_1_byte (abfd, abbrev_ptr); 124 abbrev_ptr += 1; 125 126 /* now read in declarations */ 127 for (;;) 128 { 129 LONGEST implicit_const; 130 131 abbrev_name = read_unsigned_leb128 (abfd, abbrev_ptr, &bytes_read); 132 abbrev_ptr += bytes_read; 133 abbrev_form = read_unsigned_leb128 (abfd, abbrev_ptr, &bytes_read); 134 abbrev_ptr += bytes_read; 135 if (abbrev_form == DW_FORM_implicit_const) 136 { 137 implicit_const = read_signed_leb128 (abfd, abbrev_ptr, 138 &bytes_read); 139 abbrev_ptr += bytes_read; 140 } 141 else 142 { 143 /* Initialize it due to a false compiler warning. */ 144 implicit_const = -1; 145 } 146 147 if (abbrev_name == 0) 148 break; 149 150 cur_attrs.emplace_back (); 151 struct attr_abbrev &cur_attr = cur_attrs.back (); 152 cur_attr.name = (enum dwarf_attribute) abbrev_name; 153 cur_attr.form = (enum dwarf_form) abbrev_form; 154 cur_attr.implicit_const = implicit_const; 155 } 156 157 cur_abbrev->num_attrs = cur_attrs.size (); 158 cur_abbrev->attrs = 159 XOBNEWVEC (&abbrev_table->m_abbrev_obstack, struct attr_abbrev, 160 cur_abbrev->num_attrs); 161 if (!cur_attrs.empty ()) 162 memcpy (cur_abbrev->attrs, cur_attrs.data (), 163 cur_abbrev->num_attrs * sizeof (struct attr_abbrev)); 164 165 abbrev_table->add_abbrev (cur_abbrev); 166 167 /* Get next abbreviation. 168 Under Irix6 the abbreviations for a compilation unit are not 169 always properly terminated with an abbrev number of 0. 170 Exit loop if we encounter an abbreviation which we have 171 already read (which means we are about to read the abbreviations 172 for the next compile unit) or if the end of the abbreviation 173 table is reached. */ 174 if ((unsigned int) (abbrev_ptr - section->buffer) >= section->size) 175 break; 176 abbrev_number = read_unsigned_leb128 (abfd, abbrev_ptr, &bytes_read); 177 abbrev_ptr += bytes_read; 178 if (abbrev_table->lookup_abbrev (abbrev_number) != NULL) 179 break; 180 } 181 182 return abbrev_table; 183 } 184