| 1 | /* DWARF 2 debugging format support for GDB. |
| 2 | |
| 3 | Copyright (C) 1994-2018 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 DWARF2READ_H |
| 21 | #define DWARF2READ_H |
| 22 | |
| 23 | #include "filename-seen-cache.h" |
| 24 | #include "gdb_obstack.h" |
| 25 | |
| 26 | typedef struct dwarf2_per_cu_data *dwarf2_per_cu_ptr; |
| 27 | DEF_VEC_P (dwarf2_per_cu_ptr); |
| 28 | |
| 29 | /* A descriptor for dwarf sections. |
| 30 | |
| 31 | S.ASECTION, SIZE are typically initialized when the objfile is first |
| 32 | scanned. BUFFER, READIN are filled in later when the section is read. |
| 33 | If the section contained compressed data then SIZE is updated to record |
| 34 | the uncompressed size of the section. |
| 35 | |
| 36 | DWP file format V2 introduces a wrinkle that is easiest to handle by |
| 37 | creating the concept of virtual sections contained within a real section. |
| 38 | In DWP V2 the sections of the input DWO files are concatenated together |
| 39 | into one section, but section offsets are kept relative to the original |
| 40 | input section. |
| 41 | If this is a virtual dwp-v2 section, S.CONTAINING_SECTION is a backlink to |
| 42 | the real section this "virtual" section is contained in, and BUFFER,SIZE |
| 43 | describe the virtual section. */ |
| 44 | |
| 45 | struct dwarf2_section_info |
| 46 | { |
| 47 | union |
| 48 | { |
| 49 | /* If this is a real section, the bfd section. */ |
| 50 | asection *section; |
| 51 | /* If this is a virtual section, pointer to the containing ("real") |
| 52 | section. */ |
| 53 | struct dwarf2_section_info *containing_section; |
| 54 | } s; |
| 55 | /* Pointer to section data, only valid if readin. */ |
| 56 | const gdb_byte *buffer; |
| 57 | /* The size of the section, real or virtual. */ |
| 58 | bfd_size_type size; |
| 59 | /* If this is a virtual section, the offset in the real section. |
| 60 | Only valid if is_virtual. */ |
| 61 | bfd_size_type virtual_offset; |
| 62 | /* True if we have tried to read this section. */ |
| 63 | char readin; |
| 64 | /* True if this is a virtual section, False otherwise. |
| 65 | This specifies which of s.section and s.containing_section to use. */ |
| 66 | char is_virtual; |
| 67 | }; |
| 68 | |
| 69 | typedef struct dwarf2_section_info dwarf2_section_info_def; |
| 70 | DEF_VEC_O (dwarf2_section_info_def); |
| 71 | |
| 72 | /* Read the contents of the section INFO. |
| 73 | OBJFILE is the main object file, but not necessarily the file where |
| 74 | the section comes from. E.g., for DWO files the bfd of INFO is the bfd |
| 75 | of the DWO file. |
| 76 | If the section is compressed, uncompress it before returning. */ |
| 77 | |
| 78 | void dwarf2_read_section (struct objfile *objfile, dwarf2_section_info *info); |
| 79 | |
| 80 | struct tu_stats |
| 81 | { |
| 82 | int nr_uniq_abbrev_tables; |
| 83 | int nr_symtabs; |
| 84 | int nr_symtab_sharers; |
| 85 | int nr_stmt_less_type_units; |
| 86 | int nr_all_type_units_reallocs; |
| 87 | }; |
| 88 | |
| 89 | struct dwarf2_debug_sections; |
| 90 | struct mapped_index; |
| 91 | struct mapped_debug_names; |
| 92 | struct signatured_type; |
| 93 | |
| 94 | /* Collection of data recorded per objfile. |
| 95 | This hangs off of dwarf2_objfile_data_key. */ |
| 96 | |
| 97 | struct dwarf2_per_objfile : public allocate_on_obstack |
| 98 | { |
| 99 | /* Construct a dwarf2_per_objfile for OBJFILE. NAMES points to the |
| 100 | dwarf2 section names, or is NULL if the standard ELF names are |
| 101 | used. */ |
| 102 | dwarf2_per_objfile (struct objfile *objfile, |
| 103 | const dwarf2_debug_sections *names); |
| 104 | |
| 105 | ~dwarf2_per_objfile (); |
| 106 | |
| 107 | DISABLE_COPY_AND_ASSIGN (dwarf2_per_objfile); |
| 108 | |
| 109 | /* Return the CU/TU given its index. |
| 110 | |
| 111 | This is intended for loops like: |
| 112 | |
| 113 | for (i = 0; i < (dwarf2_per_objfile->n_comp_units |
| 114 | + dwarf2_per_objfile->n_type_units); ++i) |
| 115 | { |
| 116 | dwarf2_per_cu_data *per_cu = dwarf2_per_objfile->get_cutu (i); |
| 117 | |
| 118 | ...; |
| 119 | } |
| 120 | */ |
| 121 | dwarf2_per_cu_data *get_cutu (int index); |
| 122 | |
| 123 | /* Return the CU given its index. |
| 124 | This differs from get_cutu in that it's for when you know INDEX refers to a |
| 125 | CU. */ |
| 126 | dwarf2_per_cu_data *get_cu (int index); |
| 127 | |
| 128 | /* Return the TU given its index. |
| 129 | This differs from get_cutu in that it's for when you know INDEX refers to a |
| 130 | TU. */ |
| 131 | signatured_type *get_tu (int index); |
| 132 | |
| 133 | /* Free all cached compilation units. */ |
| 134 | void free_cached_comp_units (); |
| 135 | private: |
| 136 | /* This function is mapped across the sections and remembers the |
| 137 | offset and size of each of the debugging sections we are |
| 138 | interested in. */ |
| 139 | void locate_sections (bfd *abfd, asection *sectp, |
| 140 | const dwarf2_debug_sections &names); |
| 141 | |
| 142 | public: |
| 143 | dwarf2_section_info info {}; |
| 144 | dwarf2_section_info abbrev {}; |
| 145 | dwarf2_section_info line {}; |
| 146 | dwarf2_section_info loc {}; |
| 147 | dwarf2_section_info loclists {}; |
| 148 | dwarf2_section_info macinfo {}; |
| 149 | dwarf2_section_info macro {}; |
| 150 | dwarf2_section_info str {}; |
| 151 | dwarf2_section_info line_str {}; |
| 152 | dwarf2_section_info ranges {}; |
| 153 | dwarf2_section_info rnglists {}; |
| 154 | dwarf2_section_info addr {}; |
| 155 | dwarf2_section_info frame {}; |
| 156 | dwarf2_section_info eh_frame {}; |
| 157 | dwarf2_section_info gdb_index {}; |
| 158 | dwarf2_section_info debug_names {}; |
| 159 | dwarf2_section_info debug_aranges {}; |
| 160 | |
| 161 | VEC (dwarf2_section_info_def) *types = NULL; |
| 162 | |
| 163 | /* Back link. */ |
| 164 | struct objfile *objfile = NULL; |
| 165 | |
| 166 | /* Table of all the compilation units. This is used to locate |
| 167 | the target compilation unit of a particular reference. */ |
| 168 | std::vector<dwarf2_per_cu_data *> all_comp_units; |
| 169 | |
| 170 | /* The .debug_types-related CUs (TUs). */ |
| 171 | std::vector<signatured_type *> all_type_units; |
| 172 | |
| 173 | /* Table of struct type_unit_group objects. |
| 174 | The hash key is the DW_AT_stmt_list value. */ |
| 175 | htab_t type_unit_groups {}; |
| 176 | |
| 177 | /* A table mapping .debug_types signatures to its signatured_type entry. |
| 178 | This is NULL if the .debug_types section hasn't been read in yet. */ |
| 179 | htab_t signatured_types {}; |
| 180 | |
| 181 | /* Type unit statistics, to see how well the scaling improvements |
| 182 | are doing. */ |
| 183 | struct tu_stats tu_stats {}; |
| 184 | |
| 185 | /* A chain of compilation units that are currently read in, so that |
| 186 | they can be freed later. */ |
| 187 | dwarf2_per_cu_data *read_in_chain = NULL; |
| 188 | |
| 189 | /* A table mapping DW_AT_dwo_name values to struct dwo_file objects. |
| 190 | This is NULL if the table hasn't been allocated yet. */ |
| 191 | htab_t dwo_files {}; |
| 192 | |
| 193 | /* True if we've checked for whether there is a DWP file. */ |
| 194 | bool dwp_checked = false; |
| 195 | |
| 196 | /* The DWP file if there is one, or NULL. */ |
| 197 | struct dwp_file *dwp_file = NULL; |
| 198 | |
| 199 | /* The shared '.dwz' file, if one exists. This is used when the |
| 200 | original data was compressed using 'dwz -m'. */ |
| 201 | struct dwz_file *dwz_file = NULL; |
| 202 | |
| 203 | /* A flag indicating whether this objfile has a section loaded at a |
| 204 | VMA of 0. */ |
| 205 | bool has_section_at_zero = false; |
| 206 | |
| 207 | /* True if we are using the mapped index, |
| 208 | or we are faking it for OBJF_READNOW's sake. */ |
| 209 | bool using_index = false; |
| 210 | |
| 211 | /* The mapped index, or NULL if .gdb_index is missing or not being used. */ |
| 212 | mapped_index *index_table = NULL; |
| 213 | |
| 214 | /* The mapped index, or NULL if .debug_names is missing or not being used. */ |
| 215 | std::unique_ptr<mapped_debug_names> debug_names_table; |
| 216 | |
| 217 | /* When using index_table, this keeps track of all quick_file_names entries. |
| 218 | TUs typically share line table entries with a CU, so we maintain a |
| 219 | separate table of all line table entries to support the sharing. |
| 220 | Note that while there can be way more TUs than CUs, we've already |
| 221 | sorted all the TUs into "type unit groups", grouped by their |
| 222 | DW_AT_stmt_list value. Therefore the only sharing done here is with a |
| 223 | CU and its associated TU group if there is one. */ |
| 224 | htab_t quick_file_names_table {}; |
| 225 | |
| 226 | /* Set during partial symbol reading, to prevent queueing of full |
| 227 | symbols. */ |
| 228 | bool reading_partial_symbols = false; |
| 229 | |
| 230 | /* Table mapping type DIEs to their struct type *. |
| 231 | This is NULL if not allocated yet. |
| 232 | The mapping is done via (CU/TU + DIE offset) -> type. */ |
| 233 | htab_t die_type_hash {}; |
| 234 | |
| 235 | /* The CUs we recently read. */ |
| 236 | VEC (dwarf2_per_cu_ptr) *just_read_cus = NULL; |
| 237 | |
| 238 | /* Table containing line_header indexed by offset and offset_in_dwz. */ |
| 239 | htab_t line_header_hash {}; |
| 240 | |
| 241 | /* Table containing all filenames. This is an optional because the |
| 242 | table is lazily constructed on first access. */ |
| 243 | gdb::optional<filename_seen_cache> filenames_cache; |
| 244 | }; |
| 245 | |
| 246 | /* Get the dwarf2_per_objfile associated to OBJFILE. */ |
| 247 | |
| 248 | dwarf2_per_objfile *get_dwarf2_per_objfile (struct objfile *objfile); |
| 249 | |
| 250 | /* Persistent data held for a compilation unit, even when not |
| 251 | processing it. We put a pointer to this structure in the |
| 252 | read_symtab_private field of the psymtab. */ |
| 253 | |
| 254 | struct dwarf2_per_cu_data |
| 255 | { |
| 256 | /* The start offset and length of this compilation unit. |
| 257 | NOTE: Unlike comp_unit_head.length, this length includes |
| 258 | initial_length_size. |
| 259 | If the DIE refers to a DWO file, this is always of the original die, |
| 260 | not the DWO file. */ |
| 261 | sect_offset sect_off; |
| 262 | unsigned int length; |
| 263 | |
| 264 | /* DWARF standard version this data has been read from (such as 4 or 5). */ |
| 265 | short dwarf_version; |
| 266 | |
| 267 | /* Flag indicating this compilation unit will be read in before |
| 268 | any of the current compilation units are processed. */ |
| 269 | unsigned int queued : 1; |
| 270 | |
| 271 | /* This flag will be set when reading partial DIEs if we need to load |
| 272 | absolutely all DIEs for this compilation unit, instead of just the ones |
| 273 | we think are interesting. It gets set if we look for a DIE in the |
| 274 | hash table and don't find it. */ |
| 275 | unsigned int load_all_dies : 1; |
| 276 | |
| 277 | /* Non-zero if this CU is from .debug_types. |
| 278 | Struct dwarf2_per_cu_data is contained in struct signatured_type iff |
| 279 | this is non-zero. */ |
| 280 | unsigned int is_debug_types : 1; |
| 281 | |
| 282 | /* Non-zero if this CU is from the .dwz file. */ |
| 283 | unsigned int is_dwz : 1; |
| 284 | |
| 285 | /* Non-zero if reading a TU directly from a DWO file, bypassing the stub. |
| 286 | This flag is only valid if is_debug_types is true. |
| 287 | We can't read a CU directly from a DWO file: There are required |
| 288 | attributes in the stub. */ |
| 289 | unsigned int reading_dwo_directly : 1; |
| 290 | |
| 291 | /* Non-zero if the TU has been read. |
| 292 | This is used to assist the "Stay in DWO Optimization" for Fission: |
| 293 | When reading a DWO, it's faster to read TUs from the DWO instead of |
| 294 | fetching them from random other DWOs (due to comdat folding). |
| 295 | If the TU has already been read, the optimization is unnecessary |
| 296 | (and unwise - we don't want to change where gdb thinks the TU lives |
| 297 | "midflight"). |
| 298 | This flag is only valid if is_debug_types is true. */ |
| 299 | unsigned int tu_read : 1; |
| 300 | |
| 301 | /* The section this CU/TU lives in. |
| 302 | If the DIE refers to a DWO file, this is always the original die, |
| 303 | not the DWO file. */ |
| 304 | struct dwarf2_section_info *section; |
| 305 | |
| 306 | /* Set to non-NULL iff this CU is currently loaded. When it gets freed out |
| 307 | of the CU cache it gets reset to NULL again. This is left as NULL for |
| 308 | dummy CUs (a CU header, but nothing else). */ |
| 309 | struct dwarf2_cu *cu; |
| 310 | |
| 311 | /* The corresponding dwarf2_per_objfile. */ |
| 312 | struct dwarf2_per_objfile *dwarf2_per_objfile; |
| 313 | |
| 314 | /* When dwarf2_per_objfile->using_index is true, the 'quick' field |
| 315 | is active. Otherwise, the 'psymtab' field is active. */ |
| 316 | union |
| 317 | { |
| 318 | /* The partial symbol table associated with this compilation unit, |
| 319 | or NULL for unread partial units. */ |
| 320 | struct partial_symtab *psymtab; |
| 321 | |
| 322 | /* Data needed by the "quick" functions. */ |
| 323 | struct dwarf2_per_cu_quick_data *quick; |
| 324 | } v; |
| 325 | |
| 326 | /* The CUs we import using DW_TAG_imported_unit. This is filled in |
| 327 | while reading psymtabs, used to compute the psymtab dependencies, |
| 328 | and then cleared. Then it is filled in again while reading full |
| 329 | symbols, and only deleted when the objfile is destroyed. |
| 330 | |
| 331 | This is also used to work around a difference between the way gold |
| 332 | generates .gdb_index version <=7 and the way gdb does. Arguably this |
| 333 | is a gold bug. For symbols coming from TUs, gold records in the index |
| 334 | the CU that includes the TU instead of the TU itself. This breaks |
| 335 | dw2_lookup_symbol: It assumes that if the index says symbol X lives |
| 336 | in CU/TU Y, then one need only expand Y and a subsequent lookup in Y |
| 337 | will find X. Alas TUs live in their own symtab, so after expanding CU Y |
| 338 | we need to look in TU Z to find X. Fortunately, this is akin to |
| 339 | DW_TAG_imported_unit, so we just use the same mechanism: For |
| 340 | .gdb_index version <=7 this also records the TUs that the CU referred |
| 341 | to. Concurrently with this change gdb was modified to emit version 8 |
| 342 | indices so we only pay a price for gold generated indices. |
| 343 | http://sourceware.org/bugzilla/show_bug.cgi?id=15021. */ |
| 344 | VEC (dwarf2_per_cu_ptr) *imported_symtabs; |
| 345 | }; |
| 346 | |
| 347 | /* Entry in the signatured_types hash table. */ |
| 348 | |
| 349 | struct signatured_type |
| 350 | { |
| 351 | /* The "per_cu" object of this type. |
| 352 | This struct is used iff per_cu.is_debug_types. |
| 353 | N.B.: This is the first member so that it's easy to convert pointers |
| 354 | between them. */ |
| 355 | struct dwarf2_per_cu_data per_cu; |
| 356 | |
| 357 | /* The type's signature. */ |
| 358 | ULONGEST signature; |
| 359 | |
| 360 | /* Offset in the TU of the type's DIE, as read from the TU header. |
| 361 | If this TU is a DWO stub and the definition lives in a DWO file |
| 362 | (specified by DW_AT_GNU_dwo_name), this value is unusable. */ |
| 363 | cu_offset type_offset_in_tu; |
| 364 | |
| 365 | /* Offset in the section of the type's DIE. |
| 366 | If the definition lives in a DWO file, this is the offset in the |
| 367 | .debug_types.dwo section. |
| 368 | The value is zero until the actual value is known. |
| 369 | Zero is otherwise not a valid section offset. */ |
| 370 | sect_offset type_offset_in_section; |
| 371 | |
| 372 | /* Type units are grouped by their DW_AT_stmt_list entry so that they |
| 373 | can share them. This points to the containing symtab. */ |
| 374 | struct type_unit_group *type_unit_group; |
| 375 | |
| 376 | /* The type. |
| 377 | The first time we encounter this type we fully read it in and install it |
| 378 | in the symbol tables. Subsequent times we only need the type. */ |
| 379 | struct type *type; |
| 380 | |
| 381 | /* Containing DWO unit. |
| 382 | This field is valid iff per_cu.reading_dwo_directly. */ |
| 383 | struct dwo_unit *dwo_unit; |
| 384 | }; |
| 385 | |
| 386 | typedef struct signatured_type *sig_type_ptr; |
| 387 | DEF_VEC_P (sig_type_ptr); |
| 388 | |
| 389 | #endif /* DWARF2READ_H */ |