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 /* Objects that can be shared across objfiles are stored in this
130 obstack or on the psymtab obstack, while objects that are
131 objfile-specific are stored on the objfile obstack. */
132 auto_obstack obstack
;
134 dwarf2_section_info info
{};
135 dwarf2_section_info abbrev
{};
136 dwarf2_section_info line
{};
137 dwarf2_section_info loc
{};
138 dwarf2_section_info loclists
{};
139 dwarf2_section_info macinfo
{};
140 dwarf2_section_info macro
{};
141 dwarf2_section_info str
{};
142 dwarf2_section_info str_offsets
{};
143 dwarf2_section_info line_str
{};
144 dwarf2_section_info ranges
{};
145 dwarf2_section_info rnglists
{};
146 dwarf2_section_info addr
{};
147 dwarf2_section_info frame
{};
148 dwarf2_section_info eh_frame
{};
149 dwarf2_section_info gdb_index
{};
150 dwarf2_section_info debug_names
{};
151 dwarf2_section_info debug_aranges
{};
153 std::vector
<dwarf2_section_info
> types
;
156 struct objfile
*objfile
= NULL
;
158 /* Table of all the compilation units. This is used to locate
159 the target compilation unit of a particular reference. */
160 std::vector
<dwarf2_per_cu_data
*> all_comp_units
;
162 /* The .debug_types-related CUs (TUs). */
163 std::vector
<signatured_type
*> all_type_units
;
165 /* Table of struct type_unit_group objects.
166 The hash key is the DW_AT_stmt_list value. */
167 htab_up type_unit_groups
;
169 /* A table mapping .debug_types signatures to its signatured_type entry.
170 This is NULL if the .debug_types section hasn't been read in yet. */
171 htab_up signatured_types
;
173 /* Type unit statistics, to see how well the scaling improvements
175 struct tu_stats tu_stats
{};
177 /* A chain of compilation units that are currently read in, so that
178 they can be freed later. */
179 dwarf2_per_cu_data
*read_in_chain
= NULL
;
181 /* A table mapping DW_AT_dwo_name values to struct dwo_file objects.
182 This is NULL if the table hasn't been allocated yet. */
185 /* True if we've checked for whether there is a DWP file. */
186 bool dwp_checked
= false;
188 /* The DWP file if there is one, or NULL. */
189 std::unique_ptr
<struct dwp_file
> dwp_file
;
191 /* The shared '.dwz' file, if one exists. This is used when the
192 original data was compressed using 'dwz -m'. */
193 std::unique_ptr
<struct dwz_file
> dwz_file
;
195 /* Whether copy relocations are supported by this object format. */
198 /* A flag indicating whether this objfile has a section loaded at a
200 bool has_section_at_zero
= false;
202 /* True if we are using the mapped index,
203 or we are faking it for OBJF_READNOW's sake. */
204 bool using_index
= false;
206 /* The mapped index, or NULL if .gdb_index is missing or not being used. */
207 std::unique_ptr
<mapped_index
> index_table
;
209 /* The mapped index, or NULL if .debug_names is missing or not being used. */
210 std::unique_ptr
<mapped_debug_names
> debug_names_table
;
212 /* When using index_table, this keeps track of all quick_file_names entries.
213 TUs typically share line table entries with a CU, so we maintain a
214 separate table of all line table entries to support the sharing.
215 Note that while there can be way more TUs than CUs, we've already
216 sorted all the TUs into "type unit groups", grouped by their
217 DW_AT_stmt_list value. Therefore the only sharing done here is with a
218 CU and its associated TU group if there is one. */
219 htab_up quick_file_names_table
;
221 /* Set during partial symbol reading, to prevent queueing of full
223 bool reading_partial_symbols
= false;
225 /* Table mapping type DIEs to their struct type *.
226 This is NULL if not allocated yet.
227 The mapping is done via (CU/TU + DIE offset) -> type. */
228 htab_up die_type_hash
;
230 /* The CUs we recently read. */
231 std::vector
<dwarf2_per_cu_data
*> just_read_cus
;
233 /* Table containing line_header indexed by offset and offset_in_dwz. */
234 htab_up line_header_hash
;
236 /* Table containing all filenames. This is an optional because the
237 table is lazily constructed on first access. */
238 gdb::optional
<filename_seen_cache
> filenames_cache
;
240 /* If we loaded the index from an external file, this contains the
241 resources associated to the open file, memory mapping, etc. */
242 std::unique_ptr
<index_cache_resource
> index_cache_res
;
244 /* Mapping from abstract origin DIE to concrete DIEs that reference it as
245 DW_AT_abstract_origin. */
246 std::unordered_map
<sect_offset
, std::vector
<sect_offset
>,
247 gdb::hash_enum
<sect_offset
>>
248 abstract_to_concrete
;
250 /* CUs that are queued to be read. */
251 std::queue
<dwarf2_queue_item
> queue
;
254 /* Get the dwarf2_per_objfile associated to OBJFILE. */
256 dwarf2_per_objfile
*get_dwarf2_per_objfile (struct objfile
*objfile
);
258 /* A partial symtab specialized for DWARF. */
259 struct dwarf2_psymtab
: public standard_psymtab
261 dwarf2_psymtab (const char *filename
, struct objfile
*objfile
,
262 dwarf2_per_cu_data
*per_cu
)
263 : standard_psymtab (filename
, objfile
, 0),
268 void read_symtab (struct objfile
*) override
;
269 void expand_psymtab (struct objfile
*) override
;
271 struct dwarf2_per_cu_data
*per_cu_data
;
274 /* Persistent data held for a compilation unit, even when not
275 processing it. We put a pointer to this structure in the
278 struct dwarf2_per_cu_data
280 /* The start offset and length of this compilation unit.
281 NOTE: Unlike comp_unit_head.length, this length includes
283 If the DIE refers to a DWO file, this is always of the original die,
285 sect_offset sect_off
;
288 /* DWARF standard version this data has been read from (such as 4 or 5). */
291 /* Flag indicating this compilation unit will be read in before
292 any of the current compilation units are processed. */
293 unsigned int queued
: 1;
295 /* This flag will be set when reading partial DIEs if we need to load
296 absolutely all DIEs for this compilation unit, instead of just the ones
297 we think are interesting. It gets set if we look for a DIE in the
298 hash table and don't find it. */
299 unsigned int load_all_dies
: 1;
301 /* Non-zero if this CU is from .debug_types.
302 Struct dwarf2_per_cu_data is contained in struct signatured_type iff
304 unsigned int is_debug_types
: 1;
306 /* Non-zero if this CU is from the .dwz file. */
307 unsigned int is_dwz
: 1;
309 /* Non-zero if reading a TU directly from a DWO file, bypassing the stub.
310 This flag is only valid if is_debug_types is true.
311 We can't read a CU directly from a DWO file: There are required
312 attributes in the stub. */
313 unsigned int reading_dwo_directly
: 1;
315 /* Non-zero if the TU has been read.
316 This is used to assist the "Stay in DWO Optimization" for Fission:
317 When reading a DWO, it's faster to read TUs from the DWO instead of
318 fetching them from random other DWOs (due to comdat folding).
319 If the TU has already been read, the optimization is unnecessary
320 (and unwise - we don't want to change where gdb thinks the TU lives
322 This flag is only valid if is_debug_types is true. */
323 unsigned int tu_read
: 1;
325 /* The section this CU/TU lives in.
326 If the DIE refers to a DWO file, this is always the original die,
328 struct dwarf2_section_info
*section
;
330 /* Set to non-NULL iff this CU is currently loaded. When it gets freed out
331 of the CU cache it gets reset to NULL again. This is left as NULL for
332 dummy CUs (a CU header, but nothing else). */
333 struct dwarf2_cu
*cu
;
335 /* The unit type of this CU. */
336 enum dwarf_unit_type unit_type
;
338 /* The language of this CU. */
341 /* The corresponding dwarf2_per_objfile. */
342 struct dwarf2_per_objfile
*dwarf2_per_objfile
;
344 /* When dwarf2_per_objfile->using_index is true, the 'quick' field
345 is active. Otherwise, the 'psymtab' field is active. */
348 /* The partial symbol table associated with this compilation unit,
349 or NULL for unread partial units. */
350 dwarf2_psymtab
*psymtab
;
352 /* Data needed by the "quick" functions. */
353 struct dwarf2_per_cu_quick_data
*quick
;
356 /* The CUs we import using DW_TAG_imported_unit. This is filled in
357 while reading psymtabs, used to compute the psymtab dependencies,
358 and then cleared. Then it is filled in again while reading full
359 symbols, and only deleted when the objfile is destroyed.
361 This is also used to work around a difference between the way gold
362 generates .gdb_index version <=7 and the way gdb does. Arguably this
363 is a gold bug. For symbols coming from TUs, gold records in the index
364 the CU that includes the TU instead of the TU itself. This breaks
365 dw2_lookup_symbol: It assumes that if the index says symbol X lives
366 in CU/TU Y, then one need only expand Y and a subsequent lookup in Y
367 will find X. Alas TUs live in their own symtab, so after expanding CU Y
368 we need to look in TU Z to find X. Fortunately, this is akin to
369 DW_TAG_imported_unit, so we just use the same mechanism: For
370 .gdb_index version <=7 this also records the TUs that the CU referred
371 to. Concurrently with this change gdb was modified to emit version 8
372 indices so we only pay a price for gold generated indices.
373 http://sourceware.org/bugzilla/show_bug.cgi?id=15021.
375 This currently needs to be a public member due to how
376 dwarf2_per_cu_data is allocated and used. Ideally in future things
377 could be refactored to make this private. Until then please try to
378 avoid direct access to this member, and instead use the helper
380 std::vector
<dwarf2_per_cu_data
*> *imported_symtabs
;
382 /* Return true of IMPORTED_SYMTABS is empty or not yet allocated. */
383 bool imported_symtabs_empty () const
385 return (imported_symtabs
== nullptr || imported_symtabs
->empty ());
388 /* Push P to the back of IMPORTED_SYMTABS, allocated IMPORTED_SYMTABS
389 first if required. */
390 void imported_symtabs_push (dwarf2_per_cu_data
*p
)
392 if (imported_symtabs
== nullptr)
393 imported_symtabs
= new std::vector
<dwarf2_per_cu_data
*>;
394 imported_symtabs
->push_back (p
);
397 /* Return the size of IMPORTED_SYMTABS if it is allocated, otherwise
399 size_t imported_symtabs_size () const
401 if (imported_symtabs
== nullptr)
403 return imported_symtabs
->size ();
406 /* Delete IMPORTED_SYMTABS and set the pointer back to nullptr. */
407 void imported_symtabs_free ()
409 delete imported_symtabs
;
410 imported_symtabs
= nullptr;
413 /* Return the OBJFILE associated with this compilation unit. If
414 this compilation unit came from a separate debuginfo file, then
415 the master objfile is returned. */
416 struct objfile
*objfile () const;
418 /* Return the address size given in the compilation unit header for
420 int addr_size () const;
422 /* Return the offset size given in the compilation unit header for
424 int offset_size () const;
426 /* Return the DW_FORM_ref_addr size given in the compilation unit
427 header for this CU. */
428 int ref_addr_size () const;
430 /* Return the text offset of the CU. The returned offset comes from
431 this CU's objfile. If this objfile came from a separate
432 debuginfo file, then the offset may be different from the
433 corresponding offset in the parent objfile. */
434 CORE_ADDR
text_offset () const;
436 /* Return a type that is a generic pointer type, the size of which
437 matches the address size given in the compilation unit header for
439 struct type
*addr_type () const;
441 /* Find an integer type SIZE_IN_BYTES bytes in size and return it.
442 UNSIGNED_P controls if the integer is unsigned or not. */
443 struct type
*int_type (int size_in_bytes
, bool unsigned_p
) const;
445 /* Find an integer type the same size as the address size given in
446 the compilation unit header for this CU. UNSIGNED_P controls if
447 the integer is unsigned or not. */
448 struct type
*addr_sized_int_type (bool unsigned_p
) const;
450 /* Return DWARF version number of this CU. */
451 short version () const
453 return dwarf_version
;
456 /* A type unit group has a per_cu object that is recognized by
457 having no section. */
458 bool type_unit_group_p () const
460 return section
== nullptr;
464 /* Entry in the signatured_types hash table. */
466 struct signatured_type
468 /* The "per_cu" object of this type.
469 This struct is used iff per_cu.is_debug_types.
470 N.B.: This is the first member so that it's easy to convert pointers
472 struct dwarf2_per_cu_data per_cu
;
474 /* The type's signature. */
477 /* Offset in the TU of the type's DIE, as read from the TU header.
478 If this TU is a DWO stub and the definition lives in a DWO file
479 (specified by DW_AT_GNU_dwo_name), this value is unusable. */
480 cu_offset type_offset_in_tu
;
482 /* Offset in the section of the type's DIE.
483 If the definition lives in a DWO file, this is the offset in the
484 .debug_types.dwo section.
485 The value is zero until the actual value is known.
486 Zero is otherwise not a valid section offset. */
487 sect_offset type_offset_in_section
;
489 /* Type units are grouped by their DW_AT_stmt_list entry so that they
490 can share them. This points to the containing symtab. */
491 struct type_unit_group
*type_unit_group
;
494 The first time we encounter this type we fully read it in and install it
495 in the symbol tables. Subsequent times we only need the type. */
498 /* Containing DWO unit.
499 This field is valid iff per_cu.reading_dwo_directly. */
500 struct dwo_unit
*dwo_unit
;
503 /* Open the separate '.dwz' debug file, if needed. Return NULL if
504 there is no .gnu_debugaltlink section in the file. Error if there
505 is such a section but the file cannot be found. */
507 extern struct dwz_file
*dwarf2_get_dwz_file
508 (struct dwarf2_per_objfile
*dwarf2_per_objfile
);
510 /* Return the type of the DIE at DIE_OFFSET in the CU named by
513 struct type
*dwarf2_get_die_type (cu_offset die_offset
,
514 struct dwarf2_per_cu_data
*per_cu
);
516 /* Given an index in .debug_addr, fetch the value.
517 NOTE: This can be called during dwarf expression evaluation,
518 long after the debug information has been read, and thus per_cu->cu
519 may no longer exist. */
521 CORE_ADDR
dwarf2_read_addr_index (dwarf2_per_cu_data
*per_cu
,
522 unsigned int addr_index
);
524 /* Return DWARF block referenced by DW_AT_location of DIE at SECT_OFF at PER_CU.
525 Returned value is intended for DW_OP_call*. Returned
526 dwarf2_locexpr_baton->data has lifetime of
527 PER_CU->DWARF2_PER_OBJFILE->OBJFILE. */
529 struct dwarf2_locexpr_baton dwarf2_fetch_die_loc_sect_off
530 (sect_offset sect_off
, dwarf2_per_cu_data
*per_cu
,
531 CORE_ADDR (*get_frame_pc
) (void *baton
),
532 void *baton
, bool resolve_abstract_p
= false);
534 /* Like dwarf2_fetch_die_loc_sect_off, but take a CU
537 struct dwarf2_locexpr_baton dwarf2_fetch_die_loc_cu_off
538 (cu_offset offset_in_cu
, dwarf2_per_cu_data
*per_cu
,
539 CORE_ADDR (*get_frame_pc
) (void *baton
),
542 /* If the DIE at SECT_OFF in PER_CU has a DW_AT_const_value, return a
543 pointer to the constant bytes and set LEN to the length of the
544 data. If memory is needed, allocate it on OBSTACK. If the DIE
545 does not have a DW_AT_const_value, return NULL. */
547 extern const gdb_byte
*dwarf2_fetch_constant_bytes
548 (sect_offset sect_off
, dwarf2_per_cu_data
*per_cu
, obstack
*obstack
,
551 /* Return the type of the die at SECT_OFF in PER_CU. Return NULL if no
552 valid type for this die is found. */
554 struct type
*dwarf2_fetch_die_type_sect_off
555 (sect_offset sect_off
, dwarf2_per_cu_data
*per_cu
);
557 /* When non-zero, dump line number entries as they are read in. */
558 extern unsigned int dwarf_line_debug
;
560 #endif /* DWARF2READ_H */