1 /* DWARF 2 debugging format support for GDB.
3 Copyright (C) 1994-2020 Free Software Foundation, Inc.
5 This file is part of GDB.
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.
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.
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/>. */
24 #include <unordered_map>
25 #include "dwarf2/index-cache.h"
26 #include "dwarf2/section.h"
27 #include "filename-seen-cache.h"
28 #include "gdb_obstack.h"
29 #include "gdbsupport/hash_enum.h"
32 /* Hold 'maintenance (set|show) dwarf' commands. */
33 extern struct cmd_list_element
*set_dwarf_cmdlist
;
34 extern struct cmd_list_element
*show_dwarf_cmdlist
;
38 int nr_uniq_abbrev_tables
;
40 int nr_symtab_sharers
;
41 int nr_stmt_less_type_units
;
42 int nr_all_type_units_reallocs
;
45 struct dwarf2_debug_sections
;
46 struct dwarf2_per_cu_data
;
48 struct mapped_debug_names
;
49 struct signatured_type
;
51 /* One item on the queue of compilation units to read in full symbols
53 struct dwarf2_queue_item
55 dwarf2_queue_item (dwarf2_per_cu_data
*cu
, enum language lang
)
57 pretend_language (lang
)
61 ~dwarf2_queue_item ();
63 DISABLE_COPY_AND_ASSIGN (dwarf2_queue_item
);
65 struct dwarf2_per_cu_data
*per_cu
;
66 enum language pretend_language
;
69 /* Collection of data recorded per objfile.
70 This hangs off of dwarf2_objfile_data_key. */
72 struct dwarf2_per_objfile
74 /* Construct a dwarf2_per_objfile for OBJFILE. NAMES points to the
75 dwarf2 section names, or is NULL if the standard ELF names are
76 used. CAN_COPY is true for formats where symbol
77 interposition is possible and so symbol values must follow copy
79 dwarf2_per_objfile (struct objfile
*objfile
,
80 const dwarf2_debug_sections
*names
,
83 ~dwarf2_per_objfile ();
85 DISABLE_COPY_AND_ASSIGN (dwarf2_per_objfile
);
87 /* Return the CU/TU given its index.
89 This is intended for loops like:
91 for (i = 0; i < (dwarf2_per_objfile->n_comp_units
92 + dwarf2_per_objfile->n_type_units); ++i)
94 dwarf2_per_cu_data *per_cu = dwarf2_per_objfile->get_cutu (i);
99 dwarf2_per_cu_data
*get_cutu (int index
);
101 /* Return the CU given its index.
102 This differs from get_cutu in that it's for when you know INDEX refers to a
104 dwarf2_per_cu_data
*get_cu (int index
);
106 /* Return the TU given its index.
107 This differs from get_cutu in that it's for when you know INDEX refers to a
109 signatured_type
*get_tu (int index
);
111 /* Free all cached compilation units. */
112 void free_cached_comp_units ();
114 /* Return pointer to string at .debug_line_str offset as read from BUF.
115 BUF is assumed to be in a compilation unit described by CU_HEADER.
116 Return *BYTES_READ_PTR count of bytes read from BUF. */
117 const char *read_line_string (const gdb_byte
*buf
,
118 const struct comp_unit_head
*cu_header
,
119 unsigned int *bytes_read_ptr
);
122 /* This function is mapped across the sections and remembers the
123 offset and size of each of the debugging sections we are
125 void locate_sections (bfd
*abfd
, asection
*sectp
,
126 const dwarf2_debug_sections
&names
);
129 dwarf2_section_info info
{};
130 dwarf2_section_info abbrev
{};
131 dwarf2_section_info line
{};
132 dwarf2_section_info loc
{};
133 dwarf2_section_info loclists
{};
134 dwarf2_section_info macinfo
{};
135 dwarf2_section_info macro
{};
136 dwarf2_section_info str
{};
137 dwarf2_section_info str_offsets
{};
138 dwarf2_section_info line_str
{};
139 dwarf2_section_info ranges
{};
140 dwarf2_section_info rnglists
{};
141 dwarf2_section_info addr
{};
142 dwarf2_section_info frame
{};
143 dwarf2_section_info eh_frame
{};
144 dwarf2_section_info gdb_index
{};
145 dwarf2_section_info debug_names
{};
146 dwarf2_section_info debug_aranges
{};
148 std::vector
<dwarf2_section_info
> types
;
151 struct objfile
*objfile
= NULL
;
153 /* Table of all the compilation units. This is used to locate
154 the target compilation unit of a particular reference. */
155 std::vector
<dwarf2_per_cu_data
*> all_comp_units
;
157 /* The .debug_types-related CUs (TUs). */
158 std::vector
<signatured_type
*> all_type_units
;
160 /* Table of struct type_unit_group objects.
161 The hash key is the DW_AT_stmt_list value. */
162 htab_up type_unit_groups
;
164 /* A table mapping .debug_types signatures to its signatured_type entry.
165 This is NULL if the .debug_types section hasn't been read in yet. */
166 htab_up signatured_types
;
168 /* Type unit statistics, to see how well the scaling improvements
170 struct tu_stats tu_stats
{};
172 /* A chain of compilation units that are currently read in, so that
173 they can be freed later. */
174 dwarf2_per_cu_data
*read_in_chain
= NULL
;
176 /* A table mapping DW_AT_dwo_name values to struct dwo_file objects.
177 This is NULL if the table hasn't been allocated yet. */
180 /* True if we've checked for whether there is a DWP file. */
181 bool dwp_checked
= false;
183 /* The DWP file if there is one, or NULL. */
184 std::unique_ptr
<struct dwp_file
> dwp_file
;
186 /* The shared '.dwz' file, if one exists. This is used when the
187 original data was compressed using 'dwz -m'. */
188 std::unique_ptr
<struct dwz_file
> dwz_file
;
190 /* Whether copy relocations are supported by this object format. */
193 /* A flag indicating whether this objfile has a section loaded at a
195 bool has_section_at_zero
= false;
197 /* True if we are using the mapped index,
198 or we are faking it for OBJF_READNOW's sake. */
199 bool using_index
= false;
201 /* The mapped index, or NULL if .gdb_index is missing or not being used. */
202 std::unique_ptr
<mapped_index
> index_table
;
204 /* The mapped index, or NULL if .debug_names is missing or not being used. */
205 std::unique_ptr
<mapped_debug_names
> debug_names_table
;
207 /* When using index_table, this keeps track of all quick_file_names entries.
208 TUs typically share line table entries with a CU, so we maintain a
209 separate table of all line table entries to support the sharing.
210 Note that while there can be way more TUs than CUs, we've already
211 sorted all the TUs into "type unit groups", grouped by their
212 DW_AT_stmt_list value. Therefore the only sharing done here is with a
213 CU and its associated TU group if there is one. */
214 htab_up quick_file_names_table
;
216 /* Set during partial symbol reading, to prevent queueing of full
218 bool reading_partial_symbols
= false;
220 /* Table mapping type DIEs to their struct type *.
221 This is NULL if not allocated yet.
222 The mapping is done via (CU/TU + DIE offset) -> type. */
223 htab_up die_type_hash
;
225 /* The CUs we recently read. */
226 std::vector
<dwarf2_per_cu_data
*> just_read_cus
;
228 /* Table containing line_header indexed by offset and offset_in_dwz. */
229 htab_up line_header_hash
;
231 /* Table containing all filenames. This is an optional because the
232 table is lazily constructed on first access. */
233 gdb::optional
<filename_seen_cache
> filenames_cache
;
235 /* If we loaded the index from an external file, this contains the
236 resources associated to the open file, memory mapping, etc. */
237 std::unique_ptr
<index_cache_resource
> index_cache_res
;
239 /* Mapping from abstract origin DIE to concrete DIEs that reference it as
240 DW_AT_abstract_origin. */
241 std::unordered_map
<sect_offset
, std::vector
<sect_offset
>,
242 gdb::hash_enum
<sect_offset
>>
243 abstract_to_concrete
;
245 /* CUs that are queued to be read. */
246 std::queue
<dwarf2_queue_item
> queue
;
249 /* Get the dwarf2_per_objfile associated to OBJFILE. */
251 dwarf2_per_objfile
*get_dwarf2_per_objfile (struct objfile
*objfile
);
253 /* A partial symtab specialized for DWARF. */
254 struct dwarf2_psymtab
: public standard_psymtab
256 dwarf2_psymtab (const char *filename
, struct objfile
*objfile
,
257 dwarf2_per_cu_data
*per_cu
)
258 : standard_psymtab (filename
, objfile
, 0),
263 void read_symtab (struct objfile
*) override
;
264 void expand_psymtab (struct objfile
*) override
;
266 struct dwarf2_per_cu_data
*per_cu_data
;
269 /* Persistent data held for a compilation unit, even when not
270 processing it. We put a pointer to this structure in the
273 struct dwarf2_per_cu_data
275 /* The start offset and length of this compilation unit.
276 NOTE: Unlike comp_unit_head.length, this length includes
278 If the DIE refers to a DWO file, this is always of the original die,
280 sect_offset sect_off
;
283 /* DWARF standard version this data has been read from (such as 4 or 5). */
286 /* Flag indicating this compilation unit will be read in before
287 any of the current compilation units are processed. */
288 unsigned int queued
: 1;
290 /* This flag will be set when reading partial DIEs if we need to load
291 absolutely all DIEs for this compilation unit, instead of just the ones
292 we think are interesting. It gets set if we look for a DIE in the
293 hash table and don't find it. */
294 unsigned int load_all_dies
: 1;
296 /* Non-zero if this CU is from .debug_types.
297 Struct dwarf2_per_cu_data is contained in struct signatured_type iff
299 unsigned int is_debug_types
: 1;
301 /* Non-zero if this CU is from the .dwz file. */
302 unsigned int is_dwz
: 1;
304 /* Non-zero if reading a TU directly from a DWO file, bypassing the stub.
305 This flag is only valid if is_debug_types is true.
306 We can't read a CU directly from a DWO file: There are required
307 attributes in the stub. */
308 unsigned int reading_dwo_directly
: 1;
310 /* Non-zero if the TU has been read.
311 This is used to assist the "Stay in DWO Optimization" for Fission:
312 When reading a DWO, it's faster to read TUs from the DWO instead of
313 fetching them from random other DWOs (due to comdat folding).
314 If the TU has already been read, the optimization is unnecessary
315 (and unwise - we don't want to change where gdb thinks the TU lives
317 This flag is only valid if is_debug_types is true. */
318 unsigned int tu_read
: 1;
320 /* The section this CU/TU lives in.
321 If the DIE refers to a DWO file, this is always the original die,
323 struct dwarf2_section_info
*section
;
325 /* Set to non-NULL iff this CU is currently loaded. When it gets freed out
326 of the CU cache it gets reset to NULL again. This is left as NULL for
327 dummy CUs (a CU header, but nothing else). */
328 struct dwarf2_cu
*cu
;
330 /* The unit type of this CU. */
331 enum dwarf_unit_type unit_type
;
333 /* The language of this CU. */
336 /* The corresponding dwarf2_per_objfile. */
337 struct dwarf2_per_objfile
*dwarf2_per_objfile
;
339 /* When dwarf2_per_objfile->using_index is true, the 'quick' field
340 is active. Otherwise, the 'psymtab' field is active. */
343 /* The partial symbol table associated with this compilation unit,
344 or NULL for unread partial units. */
345 dwarf2_psymtab
*psymtab
;
347 /* Data needed by the "quick" functions. */
348 struct dwarf2_per_cu_quick_data
*quick
;
351 /* The CUs we import using DW_TAG_imported_unit. This is filled in
352 while reading psymtabs, used to compute the psymtab dependencies,
353 and then cleared. Then it is filled in again while reading full
354 symbols, and only deleted when the objfile is destroyed.
356 This is also used to work around a difference between the way gold
357 generates .gdb_index version <=7 and the way gdb does. Arguably this
358 is a gold bug. For symbols coming from TUs, gold records in the index
359 the CU that includes the TU instead of the TU itself. This breaks
360 dw2_lookup_symbol: It assumes that if the index says symbol X lives
361 in CU/TU Y, then one need only expand Y and a subsequent lookup in Y
362 will find X. Alas TUs live in their own symtab, so after expanding CU Y
363 we need to look in TU Z to find X. Fortunately, this is akin to
364 DW_TAG_imported_unit, so we just use the same mechanism: For
365 .gdb_index version <=7 this also records the TUs that the CU referred
366 to. Concurrently with this change gdb was modified to emit version 8
367 indices so we only pay a price for gold generated indices.
368 http://sourceware.org/bugzilla/show_bug.cgi?id=15021.
370 This currently needs to be a public member due to how
371 dwarf2_per_cu_data is allocated and used. Ideally in future things
372 could be refactored to make this private. Until then please try to
373 avoid direct access to this member, and instead use the helper
375 std::vector
<dwarf2_per_cu_data
*> *imported_symtabs
;
377 /* Return true of IMPORTED_SYMTABS is empty or not yet allocated. */
378 bool imported_symtabs_empty () const
380 return (imported_symtabs
== nullptr || imported_symtabs
->empty ());
383 /* Push P to the back of IMPORTED_SYMTABS, allocated IMPORTED_SYMTABS
384 first if required. */
385 void imported_symtabs_push (dwarf2_per_cu_data
*p
)
387 if (imported_symtabs
== nullptr)
388 imported_symtabs
= new std::vector
<dwarf2_per_cu_data
*>;
389 imported_symtabs
->push_back (p
);
392 /* Return the size of IMPORTED_SYMTABS if it is allocated, otherwise
394 size_t imported_symtabs_size () const
396 if (imported_symtabs
== nullptr)
398 return imported_symtabs
->size ();
401 /* Delete IMPORTED_SYMTABS and set the pointer back to nullptr. */
402 void imported_symtabs_free ()
404 delete imported_symtabs
;
405 imported_symtabs
= nullptr;
408 /* Return the OBJFILE associated with this compilation unit. If
409 this compilation unit came from a separate debuginfo file, then
410 the master objfile is returned. */
411 struct objfile
*objfile () const;
413 /* Return the address size given in the compilation unit header for
415 int addr_size () const;
417 /* Return the offset size given in the compilation unit header for
419 int offset_size () const;
421 /* Return the DW_FORM_ref_addr size given in the compilation unit
422 header for this CU. */
423 int ref_addr_size () const;
425 /* Return the text offset of the CU. The returned offset comes from
426 this CU's objfile. If this objfile came from a separate
427 debuginfo file, then the offset may be different from the
428 corresponding offset in the parent objfile. */
429 CORE_ADDR
text_offset () const;
431 /* Return a type that is a generic pointer type, the size of which
432 matches the address size given in the compilation unit header for
434 struct type
*addr_type () const;
436 /* Find an integer type SIZE_IN_BYTES bytes in size and return it.
437 UNSIGNED_P controls if the integer is unsigned or not. */
438 struct type
*int_type (int size_in_bytes
, bool unsigned_p
) const;
440 /* Find an integer type the same size as the address size given in
441 the compilation unit header for this CU. UNSIGNED_P controls if
442 the integer is unsigned or not. */
443 struct type
*addr_sized_int_type (bool unsigned_p
) const;
445 /* Return DWARF version number of this CU. */
446 short version () const
448 return dwarf_version
;
451 /* A type unit group has a per_cu object that is recognized by
452 having no section. */
453 bool type_unit_group_p () const
455 return section
== nullptr;
459 /* Entry in the signatured_types hash table. */
461 struct signatured_type
463 /* The "per_cu" object of this type.
464 This struct is used iff per_cu.is_debug_types.
465 N.B.: This is the first member so that it's easy to convert pointers
467 struct dwarf2_per_cu_data per_cu
;
469 /* The type's signature. */
472 /* Offset in the TU of the type's DIE, as read from the TU header.
473 If this TU is a DWO stub and the definition lives in a DWO file
474 (specified by DW_AT_GNU_dwo_name), this value is unusable. */
475 cu_offset type_offset_in_tu
;
477 /* Offset in the section of the type's DIE.
478 If the definition lives in a DWO file, this is the offset in the
479 .debug_types.dwo section.
480 The value is zero until the actual value is known.
481 Zero is otherwise not a valid section offset. */
482 sect_offset type_offset_in_section
;
484 /* Type units are grouped by their DW_AT_stmt_list entry so that they
485 can share them. This points to the containing symtab. */
486 struct type_unit_group
*type_unit_group
;
489 The first time we encounter this type we fully read it in and install it
490 in the symbol tables. Subsequent times we only need the type. */
493 /* Containing DWO unit.
494 This field is valid iff per_cu.reading_dwo_directly. */
495 struct dwo_unit
*dwo_unit
;
498 /* Open the separate '.dwz' debug file, if needed. Return NULL if
499 there is no .gnu_debugaltlink section in the file. Error if there
500 is such a section but the file cannot be found. */
502 extern struct dwz_file
*dwarf2_get_dwz_file
503 (struct dwarf2_per_objfile
*dwarf2_per_objfile
);
505 /* Return the type of the DIE at DIE_OFFSET in the CU named by
508 struct type
*dwarf2_get_die_type (cu_offset die_offset
,
509 struct dwarf2_per_cu_data
*per_cu
);
511 /* Given an index in .debug_addr, fetch the value.
512 NOTE: This can be called during dwarf expression evaluation,
513 long after the debug information has been read, and thus per_cu->cu
514 may no longer exist. */
516 CORE_ADDR
dwarf2_read_addr_index (dwarf2_per_cu_data
*per_cu
,
517 unsigned int addr_index
);
519 /* Return DWARF block referenced by DW_AT_location of DIE at SECT_OFF at PER_CU.
520 Returned value is intended for DW_OP_call*. Returned
521 dwarf2_locexpr_baton->data has lifetime of
522 PER_CU->DWARF2_PER_OBJFILE->OBJFILE. */
524 struct dwarf2_locexpr_baton dwarf2_fetch_die_loc_sect_off
525 (sect_offset sect_off
, dwarf2_per_cu_data
*per_cu
,
526 CORE_ADDR (*get_frame_pc
) (void *baton
),
527 void *baton
, bool resolve_abstract_p
= false);
529 /* Like dwarf2_fetch_die_loc_sect_off, but take a CU
532 struct dwarf2_locexpr_baton dwarf2_fetch_die_loc_cu_off
533 (cu_offset offset_in_cu
, dwarf2_per_cu_data
*per_cu
,
534 CORE_ADDR (*get_frame_pc
) (void *baton
),
537 /* If the DIE at SECT_OFF in PER_CU has a DW_AT_const_value, return a
538 pointer to the constant bytes and set LEN to the length of the
539 data. If memory is needed, allocate it on OBSTACK. If the DIE
540 does not have a DW_AT_const_value, return NULL. */
542 extern const gdb_byte
*dwarf2_fetch_constant_bytes
543 (sect_offset sect_off
, dwarf2_per_cu_data
*per_cu
, obstack
*obstack
,
546 /* Return the type of the die at SECT_OFF in PER_CU. Return NULL if no
547 valid type for this die is found. */
549 struct type
*dwarf2_fetch_die_type_sect_off
550 (sect_offset sect_off
, dwarf2_per_cu_data
*per_cu
);
552 /* When non-zero, dump line number entries as they are read in. */
553 extern unsigned int dwarf_line_debug
;
555 #endif /* DWARF2READ_H */