| 1 | /* DWARF 2 debugging format support for GDB. |
| 2 | |
| 3 | Copyright (C) 1994-2020 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 <unordered_map> |
| 24 | #include "dwarf-index-cache.h" |
| 25 | #include "filename-seen-cache.h" |
| 26 | #include "gdb_obstack.h" |
| 27 | #include "gdbsupport/hash_enum.h" |
| 28 | |
| 29 | /* Hold 'maintenance (set|show) dwarf' commands. */ |
| 30 | extern struct cmd_list_element *set_dwarf_cmdlist; |
| 31 | extern struct cmd_list_element *show_dwarf_cmdlist; |
| 32 | |
| 33 | extern bool dwarf_always_disassemble; |
| 34 | |
| 35 | /* A descriptor for dwarf sections. |
| 36 | |
| 37 | S.ASECTION, SIZE are typically initialized when the objfile is first |
| 38 | scanned. BUFFER, READIN are filled in later when the section is read. |
| 39 | If the section contained compressed data then SIZE is updated to record |
| 40 | the uncompressed size of the section. |
| 41 | |
| 42 | DWP file format V2 introduces a wrinkle that is easiest to handle by |
| 43 | creating the concept of virtual sections contained within a real section. |
| 44 | In DWP V2 the sections of the input DWO files are concatenated together |
| 45 | into one section, but section offsets are kept relative to the original |
| 46 | input section. |
| 47 | If this is a virtual dwp-v2 section, S.CONTAINING_SECTION is a backlink to |
| 48 | the real section this "virtual" section is contained in, and BUFFER,SIZE |
| 49 | describe the virtual section. */ |
| 50 | |
| 51 | struct dwarf2_section_info |
| 52 | { |
| 53 | union |
| 54 | { |
| 55 | /* If this is a real section, the bfd section. */ |
| 56 | asection *section; |
| 57 | /* If this is a virtual section, pointer to the containing ("real") |
| 58 | section. */ |
| 59 | struct dwarf2_section_info *containing_section; |
| 60 | } s; |
| 61 | /* Pointer to section data, only valid if readin. */ |
| 62 | const gdb_byte *buffer; |
| 63 | /* The size of the section, real or virtual. */ |
| 64 | bfd_size_type size; |
| 65 | /* If this is a virtual section, the offset in the real section. |
| 66 | Only valid if is_virtual. */ |
| 67 | bfd_size_type virtual_offset; |
| 68 | /* True if we have tried to read this section. */ |
| 69 | bool readin; |
| 70 | /* True if this is a virtual section, False otherwise. |
| 71 | This specifies which of s.section and s.containing_section to use. */ |
| 72 | bool is_virtual; |
| 73 | }; |
| 74 | |
| 75 | /* Read the contents of the section INFO. |
| 76 | OBJFILE is the main object file, but not necessarily the file where |
| 77 | the section comes from. E.g., for DWO files the bfd of INFO is the bfd |
| 78 | of the DWO file. |
| 79 | If the section is compressed, uncompress it before returning. */ |
| 80 | |
| 81 | void dwarf2_read_section (struct objfile *objfile, dwarf2_section_info *info); |
| 82 | |
| 83 | struct tu_stats |
| 84 | { |
| 85 | int nr_uniq_abbrev_tables; |
| 86 | int nr_symtabs; |
| 87 | int nr_symtab_sharers; |
| 88 | int nr_stmt_less_type_units; |
| 89 | int nr_all_type_units_reallocs; |
| 90 | }; |
| 91 | |
| 92 | struct dwarf2_debug_sections; |
| 93 | struct mapped_index; |
| 94 | struct mapped_debug_names; |
| 95 | struct signatured_type; |
| 96 | struct die_info; |
| 97 | typedef struct die_info *die_info_ptr; |
| 98 | |
| 99 | /* Collection of data recorded per objfile. |
| 100 | This hangs off of dwarf2_objfile_data_key. */ |
| 101 | |
| 102 | struct dwarf2_per_objfile |
| 103 | { |
| 104 | /* Construct a dwarf2_per_objfile for OBJFILE. NAMES points to the |
| 105 | dwarf2 section names, or is NULL if the standard ELF names are |
| 106 | used. CAN_COPY is true for formats where symbol |
| 107 | interposition is possible and so symbol values must follow copy |
| 108 | relocation rules. */ |
| 109 | dwarf2_per_objfile (struct objfile *objfile, |
| 110 | const dwarf2_debug_sections *names, |
| 111 | bool can_copy); |
| 112 | |
| 113 | ~dwarf2_per_objfile (); |
| 114 | |
| 115 | DISABLE_COPY_AND_ASSIGN (dwarf2_per_objfile); |
| 116 | |
| 117 | /* Return the CU/TU given its index. |
| 118 | |
| 119 | This is intended for loops like: |
| 120 | |
| 121 | for (i = 0; i < (dwarf2_per_objfile->n_comp_units |
| 122 | + dwarf2_per_objfile->n_type_units); ++i) |
| 123 | { |
| 124 | dwarf2_per_cu_data *per_cu = dwarf2_per_objfile->get_cutu (i); |
| 125 | |
| 126 | ...; |
| 127 | } |
| 128 | */ |
| 129 | dwarf2_per_cu_data *get_cutu (int index); |
| 130 | |
| 131 | /* Return the CU given its index. |
| 132 | This differs from get_cutu in that it's for when you know INDEX refers to a |
| 133 | CU. */ |
| 134 | dwarf2_per_cu_data *get_cu (int index); |
| 135 | |
| 136 | /* Return the TU given its index. |
| 137 | This differs from get_cutu in that it's for when you know INDEX refers to a |
| 138 | TU. */ |
| 139 | signatured_type *get_tu (int index); |
| 140 | |
| 141 | /* Free all cached compilation units. */ |
| 142 | void free_cached_comp_units (); |
| 143 | private: |
| 144 | /* This function is mapped across the sections and remembers the |
| 145 | offset and size of each of the debugging sections we are |
| 146 | interested in. */ |
| 147 | void locate_sections (bfd *abfd, asection *sectp, |
| 148 | const dwarf2_debug_sections &names); |
| 149 | |
| 150 | public: |
| 151 | dwarf2_section_info info {}; |
| 152 | dwarf2_section_info abbrev {}; |
| 153 | dwarf2_section_info line {}; |
| 154 | dwarf2_section_info loc {}; |
| 155 | dwarf2_section_info loclists {}; |
| 156 | dwarf2_section_info macinfo {}; |
| 157 | dwarf2_section_info macro {}; |
| 158 | dwarf2_section_info str {}; |
| 159 | dwarf2_section_info line_str {}; |
| 160 | dwarf2_section_info ranges {}; |
| 161 | dwarf2_section_info rnglists {}; |
| 162 | dwarf2_section_info addr {}; |
| 163 | dwarf2_section_info frame {}; |
| 164 | dwarf2_section_info eh_frame {}; |
| 165 | dwarf2_section_info gdb_index {}; |
| 166 | dwarf2_section_info debug_names {}; |
| 167 | dwarf2_section_info debug_aranges {}; |
| 168 | |
| 169 | std::vector<dwarf2_section_info> types; |
| 170 | |
| 171 | /* Back link. */ |
| 172 | struct objfile *objfile = NULL; |
| 173 | |
| 174 | /* Table of all the compilation units. This is used to locate |
| 175 | the target compilation unit of a particular reference. */ |
| 176 | std::vector<dwarf2_per_cu_data *> all_comp_units; |
| 177 | |
| 178 | /* The .debug_types-related CUs (TUs). */ |
| 179 | std::vector<signatured_type *> all_type_units; |
| 180 | |
| 181 | /* Table of struct type_unit_group objects. |
| 182 | The hash key is the DW_AT_stmt_list value. */ |
| 183 | htab_t type_unit_groups {}; |
| 184 | |
| 185 | /* A table mapping .debug_types signatures to its signatured_type entry. |
| 186 | This is NULL if the .debug_types section hasn't been read in yet. */ |
| 187 | htab_t signatured_types {}; |
| 188 | |
| 189 | /* Type unit statistics, to see how well the scaling improvements |
| 190 | are doing. */ |
| 191 | struct tu_stats tu_stats {}; |
| 192 | |
| 193 | /* A chain of compilation units that are currently read in, so that |
| 194 | they can be freed later. */ |
| 195 | dwarf2_per_cu_data *read_in_chain = NULL; |
| 196 | |
| 197 | /* A table mapping DW_AT_dwo_name values to struct dwo_file objects. |
| 198 | This is NULL if the table hasn't been allocated yet. */ |
| 199 | htab_up dwo_files; |
| 200 | |
| 201 | /* True if we've checked for whether there is a DWP file. */ |
| 202 | bool dwp_checked = false; |
| 203 | |
| 204 | /* The DWP file if there is one, or NULL. */ |
| 205 | std::unique_ptr<struct dwp_file> dwp_file; |
| 206 | |
| 207 | /* The shared '.dwz' file, if one exists. This is used when the |
| 208 | original data was compressed using 'dwz -m'. */ |
| 209 | std::unique_ptr<struct dwz_file> dwz_file; |
| 210 | |
| 211 | /* Whether copy relocations are supported by this object format. */ |
| 212 | bool can_copy; |
| 213 | |
| 214 | /* A flag indicating whether this objfile has a section loaded at a |
| 215 | VMA of 0. */ |
| 216 | bool has_section_at_zero = false; |
| 217 | |
| 218 | /* True if we are using the mapped index, |
| 219 | or we are faking it for OBJF_READNOW's sake. */ |
| 220 | bool using_index = false; |
| 221 | |
| 222 | /* The mapped index, or NULL if .gdb_index is missing or not being used. */ |
| 223 | std::unique_ptr<mapped_index> index_table; |
| 224 | |
| 225 | /* The mapped index, or NULL if .debug_names is missing or not being used. */ |
| 226 | std::unique_ptr<mapped_debug_names> debug_names_table; |
| 227 | |
| 228 | /* When using index_table, this keeps track of all quick_file_names entries. |
| 229 | TUs typically share line table entries with a CU, so we maintain a |
| 230 | separate table of all line table entries to support the sharing. |
| 231 | Note that while there can be way more TUs than CUs, we've already |
| 232 | sorted all the TUs into "type unit groups", grouped by their |
| 233 | DW_AT_stmt_list value. Therefore the only sharing done here is with a |
| 234 | CU and its associated TU group if there is one. */ |
| 235 | htab_t quick_file_names_table {}; |
| 236 | |
| 237 | /* Set during partial symbol reading, to prevent queueing of full |
| 238 | symbols. */ |
| 239 | bool reading_partial_symbols = false; |
| 240 | |
| 241 | /* Table mapping type DIEs to their struct type *. |
| 242 | This is NULL if not allocated yet. |
| 243 | The mapping is done via (CU/TU + DIE offset) -> type. */ |
| 244 | htab_t die_type_hash {}; |
| 245 | |
| 246 | /* The CUs we recently read. */ |
| 247 | std::vector<dwarf2_per_cu_data *> just_read_cus; |
| 248 | |
| 249 | /* Table containing line_header indexed by offset and offset_in_dwz. */ |
| 250 | htab_t line_header_hash {}; |
| 251 | |
| 252 | /* Table containing all filenames. This is an optional because the |
| 253 | table is lazily constructed on first access. */ |
| 254 | gdb::optional<filename_seen_cache> filenames_cache; |
| 255 | |
| 256 | /* If we loaded the index from an external file, this contains the |
| 257 | resources associated to the open file, memory mapping, etc. */ |
| 258 | std::unique_ptr<index_cache_resource> index_cache_res; |
| 259 | |
| 260 | /* Mapping from abstract origin DIE to concrete DIEs that reference it as |
| 261 | DW_AT_abstract_origin. */ |
| 262 | std::unordered_map<sect_offset, std::vector<sect_offset>, |
| 263 | gdb::hash_enum<sect_offset>> |
| 264 | abstract_to_concrete; |
| 265 | }; |
| 266 | |
| 267 | /* Get the dwarf2_per_objfile associated to OBJFILE. */ |
| 268 | |
| 269 | dwarf2_per_objfile *get_dwarf2_per_objfile (struct objfile *objfile); |
| 270 | |
| 271 | /* Persistent data held for a compilation unit, even when not |
| 272 | processing it. We put a pointer to this structure in the |
| 273 | read_symtab_private field of the psymtab. */ |
| 274 | |
| 275 | struct dwarf2_per_cu_data |
| 276 | { |
| 277 | /* The start offset and length of this compilation unit. |
| 278 | NOTE: Unlike comp_unit_head.length, this length includes |
| 279 | initial_length_size. |
| 280 | If the DIE refers to a DWO file, this is always of the original die, |
| 281 | not the DWO file. */ |
| 282 | sect_offset sect_off; |
| 283 | unsigned int length; |
| 284 | |
| 285 | /* DWARF standard version this data has been read from (such as 4 or 5). */ |
| 286 | short dwarf_version; |
| 287 | |
| 288 | /* Flag indicating this compilation unit will be read in before |
| 289 | any of the current compilation units are processed. */ |
| 290 | unsigned int queued : 1; |
| 291 | |
| 292 | /* This flag will be set when reading partial DIEs if we need to load |
| 293 | absolutely all DIEs for this compilation unit, instead of just the ones |
| 294 | we think are interesting. It gets set if we look for a DIE in the |
| 295 | hash table and don't find it. */ |
| 296 | unsigned int load_all_dies : 1; |
| 297 | |
| 298 | /* Non-zero if this CU is from .debug_types. |
| 299 | Struct dwarf2_per_cu_data is contained in struct signatured_type iff |
| 300 | this is non-zero. */ |
| 301 | unsigned int is_debug_types : 1; |
| 302 | |
| 303 | /* Non-zero if this CU is from the .dwz file. */ |
| 304 | unsigned int is_dwz : 1; |
| 305 | |
| 306 | /* Non-zero if reading a TU directly from a DWO file, bypassing the stub. |
| 307 | This flag is only valid if is_debug_types is true. |
| 308 | We can't read a CU directly from a DWO file: There are required |
| 309 | attributes in the stub. */ |
| 310 | unsigned int reading_dwo_directly : 1; |
| 311 | |
| 312 | /* Non-zero if the TU has been read. |
| 313 | This is used to assist the "Stay in DWO Optimization" for Fission: |
| 314 | When reading a DWO, it's faster to read TUs from the DWO instead of |
| 315 | fetching them from random other DWOs (due to comdat folding). |
| 316 | If the TU has already been read, the optimization is unnecessary |
| 317 | (and unwise - we don't want to change where gdb thinks the TU lives |
| 318 | "midflight"). |
| 319 | This flag is only valid if is_debug_types is true. */ |
| 320 | unsigned int tu_read : 1; |
| 321 | |
| 322 | /* The section this CU/TU lives in. |
| 323 | If the DIE refers to a DWO file, this is always the original die, |
| 324 | not the DWO file. */ |
| 325 | struct dwarf2_section_info *section; |
| 326 | |
| 327 | /* Set to non-NULL iff this CU is currently loaded. When it gets freed out |
| 328 | of the CU cache it gets reset to NULL again. This is left as NULL for |
| 329 | dummy CUs (a CU header, but nothing else). */ |
| 330 | struct dwarf2_cu *cu; |
| 331 | |
| 332 | /* The corresponding dwarf2_per_objfile. */ |
| 333 | struct dwarf2_per_objfile *dwarf2_per_objfile; |
| 334 | |
| 335 | /* When dwarf2_per_objfile->using_index is true, the 'quick' field |
| 336 | is active. Otherwise, the 'psymtab' field is active. */ |
| 337 | union |
| 338 | { |
| 339 | /* The partial symbol table associated with this compilation unit, |
| 340 | or NULL for unread partial units. */ |
| 341 | struct partial_symtab *psymtab; |
| 342 | |
| 343 | /* Data needed by the "quick" functions. */ |
| 344 | struct dwarf2_per_cu_quick_data *quick; |
| 345 | } v; |
| 346 | |
| 347 | /* Return true of IMPORTED_SYMTABS is empty or not yet allocated. */ |
| 348 | bool imported_symtabs_empty () const |
| 349 | { |
| 350 | return (imported_symtabs == nullptr || imported_symtabs->empty ()); |
| 351 | } |
| 352 | |
| 353 | /* Push P to the back of IMPORTED_SYMTABS, allocated IMPORTED_SYMTABS |
| 354 | first if required. */ |
| 355 | void imported_symtabs_push (dwarf2_per_cu_data *p) |
| 356 | { |
| 357 | if (imported_symtabs == nullptr) |
| 358 | imported_symtabs = new std::vector <dwarf2_per_cu_data *>; |
| 359 | imported_symtabs->push_back (p); |
| 360 | } |
| 361 | |
| 362 | /* Return the size of IMPORTED_SYMTABS if it is allocated, otherwise |
| 363 | return 0. */ |
| 364 | size_t imported_symtabs_size () const |
| 365 | { |
| 366 | if (imported_symtabs == nullptr) |
| 367 | return 0; |
| 368 | return imported_symtabs->size (); |
| 369 | } |
| 370 | |
| 371 | /* Delete IMPORTED_SYMTABS and set the pointer back to nullptr. */ |
| 372 | void imported_symtabs_free () |
| 373 | { |
| 374 | delete imported_symtabs; |
| 375 | imported_symtabs = nullptr; |
| 376 | } |
| 377 | |
| 378 | /* The CUs we import using DW_TAG_imported_unit. This is filled in |
| 379 | while reading psymtabs, used to compute the psymtab dependencies, |
| 380 | and then cleared. Then it is filled in again while reading full |
| 381 | symbols, and only deleted when the objfile is destroyed. |
| 382 | |
| 383 | This is also used to work around a difference between the way gold |
| 384 | generates .gdb_index version <=7 and the way gdb does. Arguably this |
| 385 | is a gold bug. For symbols coming from TUs, gold records in the index |
| 386 | the CU that includes the TU instead of the TU itself. This breaks |
| 387 | dw2_lookup_symbol: It assumes that if the index says symbol X lives |
| 388 | in CU/TU Y, then one need only expand Y and a subsequent lookup in Y |
| 389 | will find X. Alas TUs live in their own symtab, so after expanding CU Y |
| 390 | we need to look in TU Z to find X. Fortunately, this is akin to |
| 391 | DW_TAG_imported_unit, so we just use the same mechanism: For |
| 392 | .gdb_index version <=7 this also records the TUs that the CU referred |
| 393 | to. Concurrently with this change gdb was modified to emit version 8 |
| 394 | indices so we only pay a price for gold generated indices. |
| 395 | http://sourceware.org/bugzilla/show_bug.cgi?id=15021. |
| 396 | |
| 397 | This currently needs to be a public member due to how |
| 398 | dwarf2_per_cu_data is allocated and used. Ideally in future things |
| 399 | could be refactored to make this private. Until then please try to |
| 400 | avoid direct access to this member, and instead use the helper |
| 401 | functions above. */ |
| 402 | std::vector <dwarf2_per_cu_data *> *imported_symtabs; |
| 403 | }; |
| 404 | |
| 405 | /* Entry in the signatured_types hash table. */ |
| 406 | |
| 407 | struct signatured_type |
| 408 | { |
| 409 | /* The "per_cu" object of this type. |
| 410 | This struct is used iff per_cu.is_debug_types. |
| 411 | N.B.: This is the first member so that it's easy to convert pointers |
| 412 | between them. */ |
| 413 | struct dwarf2_per_cu_data per_cu; |
| 414 | |
| 415 | /* The type's signature. */ |
| 416 | ULONGEST signature; |
| 417 | |
| 418 | /* Offset in the TU of the type's DIE, as read from the TU header. |
| 419 | If this TU is a DWO stub and the definition lives in a DWO file |
| 420 | (specified by DW_AT_GNU_dwo_name), this value is unusable. */ |
| 421 | cu_offset type_offset_in_tu; |
| 422 | |
| 423 | /* Offset in the section of the type's DIE. |
| 424 | If the definition lives in a DWO file, this is the offset in the |
| 425 | .debug_types.dwo section. |
| 426 | The value is zero until the actual value is known. |
| 427 | Zero is otherwise not a valid section offset. */ |
| 428 | sect_offset type_offset_in_section; |
| 429 | |
| 430 | /* Type units are grouped by their DW_AT_stmt_list entry so that they |
| 431 | can share them. This points to the containing symtab. */ |
| 432 | struct type_unit_group *type_unit_group; |
| 433 | |
| 434 | /* The type. |
| 435 | The first time we encounter this type we fully read it in and install it |
| 436 | in the symbol tables. Subsequent times we only need the type. */ |
| 437 | struct type *type; |
| 438 | |
| 439 | /* Containing DWO unit. |
| 440 | This field is valid iff per_cu.reading_dwo_directly. */ |
| 441 | struct dwo_unit *dwo_unit; |
| 442 | }; |
| 443 | |
| 444 | ULONGEST read_unsigned_leb128 (bfd *, const gdb_byte *, unsigned int *); |
| 445 | |
| 446 | /* This represents a '.dwz' file. */ |
| 447 | |
| 448 | struct dwz_file |
| 449 | { |
| 450 | dwz_file (gdb_bfd_ref_ptr &&bfd) |
| 451 | : dwz_bfd (std::move (bfd)) |
| 452 | { |
| 453 | } |
| 454 | |
| 455 | const char *filename () const |
| 456 | { |
| 457 | return bfd_get_filename (this->dwz_bfd.get ()); |
| 458 | } |
| 459 | |
| 460 | /* A dwz file can only contain a few sections. */ |
| 461 | struct dwarf2_section_info abbrev {}; |
| 462 | struct dwarf2_section_info info {}; |
| 463 | struct dwarf2_section_info str {}; |
| 464 | struct dwarf2_section_info line {}; |
| 465 | struct dwarf2_section_info macro {}; |
| 466 | struct dwarf2_section_info gdb_index {}; |
| 467 | struct dwarf2_section_info debug_names {}; |
| 468 | |
| 469 | /* The dwz's BFD. */ |
| 470 | gdb_bfd_ref_ptr dwz_bfd; |
| 471 | |
| 472 | /* If we loaded the index from an external file, this contains the |
| 473 | resources associated to the open file, memory mapping, etc. */ |
| 474 | std::unique_ptr<index_cache_resource> index_cache_res; |
| 475 | }; |
| 476 | |
| 477 | /* Open the separate '.dwz' debug file, if needed. Return NULL if |
| 478 | there is no .gnu_debugaltlink section in the file. Error if there |
| 479 | is such a section but the file cannot be found. */ |
| 480 | |
| 481 | extern struct dwz_file *dwarf2_get_dwz_file |
| 482 | (struct dwarf2_per_objfile *dwarf2_per_objfile); |
| 483 | |
| 484 | #endif /* DWARF2READ_H */ |