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
;
50 struct type_unit_group
;
52 /* One item on the queue of compilation units to read in full symbols
54 struct dwarf2_queue_item
56 dwarf2_queue_item (dwarf2_per_cu_data
*cu
, dwarf2_per_objfile
*per_objfile
,
59 per_objfile (per_objfile
),
60 pretend_language (lang
)
64 ~dwarf2_queue_item ();
66 DISABLE_COPY_AND_ASSIGN (dwarf2_queue_item
);
68 dwarf2_per_cu_data
*per_cu
;
69 dwarf2_per_objfile
*per_objfile
;
70 enum language pretend_language
;
73 /* Some DWARF data can be shared across objfiles who share the same BFD,
74 this data is stored in this object.
76 Two dwarf2_per_objfile objects representing objfiles sharing the same BFD
77 will point to the same instance of dwarf2_per_bfd, unless the BFD requires
82 /* Construct a dwarf2_per_bfd for OBFD. NAMES points to the
83 dwarf2 section names, or is NULL if the standard ELF names are
84 used. CAN_COPY is true for formats where symbol
85 interposition is possible and so symbol values must follow copy
87 dwarf2_per_bfd (bfd
*obfd
, const dwarf2_debug_sections
*names
, bool can_copy
);
91 DISABLE_COPY_AND_ASSIGN (dwarf2_per_bfd
);
93 /* Return the CU/TU given its index.
95 This is intended for loops like:
97 for (i = 0; i < (dwarf2_per_bfd->n_comp_units
98 + dwarf2_per_bfd->n_type_units); ++i)
100 dwarf2_per_cu_data *per_cu = dwarf2_per_bfd->get_cutu (i);
105 dwarf2_per_cu_data
*get_cutu (int index
);
107 /* Return the CU given its index.
108 This differs from get_cutu in that it's for when you know INDEX refers to a
110 dwarf2_per_cu_data
*get_cu (int index
);
112 /* Return the TU given its index.
113 This differs from get_cutu in that it's for when you know INDEX refers to a
115 signatured_type
*get_tu (int index
);
117 /* Free all cached compilation units. */
118 void free_cached_comp_units ();
120 /* A convenience function to allocate a dwarf2_per_cu_data. The
121 returned object has its "index" field set properly. The object
122 is allocated on the dwarf2_per_bfd obstack. */
123 dwarf2_per_cu_data
*allocate_per_cu ();
125 /* A convenience function to allocate a signatured_type. The
126 returned object has its "index" field set properly. The object
127 is allocated on the dwarf2_per_bfd obstack. */
128 signatured_type
*allocate_signatured_type ();
130 /* Return the number of partial symtabs allocated with allocate_per_cu
131 and allocate_signatured_type so far. */
132 int num_psymtabs () const
133 { return m_num_psymtabs
; }
136 /* This function is mapped across the sections and remembers the
137 offset and size of each of the debugging sections we are
139 void locate_sections (bfd
*abfd
, asection
*sectp
,
140 const dwarf2_debug_sections
&names
);
143 /* The corresponding BFD. */
146 /* Objects that can be shared across objfiles are stored in this
147 obstack or on the psymtab obstack, while objects that are
148 objfile-specific are stored on the objfile obstack. */
149 auto_obstack obstack
;
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 str_offsets
{};
160 dwarf2_section_info line_str
{};
161 dwarf2_section_info ranges
{};
162 dwarf2_section_info rnglists
{};
163 dwarf2_section_info addr
{};
164 dwarf2_section_info frame
{};
165 dwarf2_section_info eh_frame
{};
166 dwarf2_section_info gdb_index
{};
167 dwarf2_section_info debug_names
{};
168 dwarf2_section_info debug_aranges
{};
170 std::vector
<dwarf2_section_info
> types
;
172 /* Table of all the compilation units. This is used to locate
173 the target compilation unit of a particular reference. */
174 std::vector
<dwarf2_per_cu_data
*> all_comp_units
;
176 /* The .debug_types-related CUs (TUs). */
177 std::vector
<signatured_type
*> all_type_units
;
179 /* Table of struct type_unit_group objects.
180 The hash key is the DW_AT_stmt_list value. */
181 htab_up type_unit_groups
;
183 /* A table mapping .debug_types signatures to its signatured_type entry.
184 This is NULL if the .debug_types section hasn't been read in yet. */
185 htab_up signatured_types
;
187 /* Type unit statistics, to see how well the scaling improvements
189 struct tu_stats tu_stats
{};
191 /* A chain of compilation units that are currently read in, so that
192 they can be freed later. */
193 dwarf2_per_cu_data
*read_in_chain
= NULL
;
195 /* A table mapping DW_AT_dwo_name values to struct dwo_file objects.
196 This is NULL if the table hasn't been allocated yet. */
199 /* True if we've checked for whether there is a DWP file. */
200 bool dwp_checked
= false;
202 /* The DWP file if there is one, or NULL. */
203 std::unique_ptr
<struct dwp_file
> dwp_file
;
205 /* The shared '.dwz' file, if one exists. This is used when the
206 original data was compressed using 'dwz -m'. */
207 std::unique_ptr
<struct dwz_file
> dwz_file
;
209 /* Whether copy relocations are supported by this object format. */
212 /* A flag indicating whether this objfile has a section loaded at a
214 bool has_section_at_zero
= false;
216 /* True if we are using the mapped index,
217 or we are faking it for OBJF_READNOW's sake. */
218 bool using_index
= false;
220 /* The mapped index, or NULL if .gdb_index is missing or not being used. */
221 std::unique_ptr
<mapped_index
> index_table
;
223 /* The mapped index, or NULL if .debug_names is missing or not being used. */
224 std::unique_ptr
<mapped_debug_names
> debug_names_table
;
226 /* When using index_table, this keeps track of all quick_file_names entries.
227 TUs typically share line table entries with a CU, so we maintain a
228 separate table of all line table entries to support the sharing.
229 Note that while there can be way more TUs than CUs, we've already
230 sorted all the TUs into "type unit groups", grouped by their
231 DW_AT_stmt_list value. Therefore the only sharing done here is with a
232 CU and its associated TU group if there is one. */
233 htab_up quick_file_names_table
;
235 /* Set during partial symbol reading, to prevent queueing of full
237 bool reading_partial_symbols
= false;
239 /* The CUs we recently read. */
240 std::vector
<dwarf2_per_cu_data
*> just_read_cus
;
242 /* Table containing line_header indexed by offset and offset_in_dwz. */
243 htab_up line_header_hash
;
245 /* Table containing all filenames. This is an optional because the
246 table is lazily constructed on first access. */
247 gdb::optional
<filename_seen_cache
> filenames_cache
;
249 /* If we loaded the index from an external file, this contains the
250 resources associated to the open file, memory mapping, etc. */
251 std::unique_ptr
<index_cache_resource
> index_cache_res
;
253 /* Mapping from abstract origin DIE to concrete DIEs that reference it as
254 DW_AT_abstract_origin. */
255 std::unordered_map
<sect_offset
, std::vector
<sect_offset
>,
256 gdb::hash_enum
<sect_offset
>>
257 abstract_to_concrete
;
259 /* CUs that are queued to be read. */
260 std::queue
<dwarf2_queue_item
> queue
;
264 /* The total number of per_cu and signatured_type objects that have
265 been created so far for this reader. */
266 size_t m_num_psymtabs
= 0;
269 /* This is the per-objfile data associated with a type_unit_group. */
271 struct type_unit_group_unshareable
273 /* The compunit symtab.
274 Type units in a group needn't all be defined in the same source file,
275 so we create an essentially anonymous symtab as the compunit symtab. */
276 struct compunit_symtab
*compunit_symtab
= nullptr;
278 /* The number of symtabs from the line header.
279 The value here must match line_header.num_file_names. */
280 unsigned int num_symtabs
= 0;
282 /* The symbol tables for this TU (obtained from the files listed in
284 WARNING: The order of entries here must match the order of entries
285 in the line header. After the first TU using this type_unit_group, the
286 line header for the subsequent TUs is recreated from this. This is done
287 because we need to use the same symtabs for each TU using the same
288 DW_AT_stmt_list value. Also note that symtabs may be repeated here,
289 there's no guarantee the line header doesn't have duplicate entries. */
290 struct symtab
**symtabs
= nullptr;
293 /* Collection of data recorded per objfile.
294 This hangs off of dwarf2_objfile_data_key.
296 Some DWARF data cannot (currently) be shared across objfiles. Such
297 data is stored in this object. */
299 struct dwarf2_per_objfile
301 dwarf2_per_objfile (struct objfile
*objfile
, dwarf2_per_bfd
*per_bfd
)
302 : objfile (objfile
), per_bfd (per_bfd
)
305 /* Return pointer to string at .debug_line_str offset as read from BUF.
306 BUF is assumed to be in a compilation unit described by CU_HEADER.
307 Return *BYTES_READ_PTR count of bytes read from BUF. */
308 const char *read_line_string (const gdb_byte
*buf
,
309 const struct comp_unit_head
*cu_header
,
310 unsigned int *bytes_read_ptr
);
312 /* Resize the M_SYMTABS vector to the needed size (the number of partial
313 symtabs allocated by the per-bfd). */
314 void resize_symtabs ()
316 /* The symtabs vector should only grow, not shrink. */
317 gdb_assert (per_bfd
->num_psymtabs () >= m_symtabs
.size ());
319 m_symtabs
.resize (per_bfd
->num_psymtabs ());
322 /* Return true if the symtab corresponding to PER_CU has been set,
324 bool symtab_set_p (const dwarf2_per_cu_data
*per_cu
) const;
326 /* Return the compunit_symtab associated to PER_CU, if it has been created. */
327 compunit_symtab
*get_symtab (const dwarf2_per_cu_data
*per_cu
) const;
329 /* Set the compunit_symtab associated to PER_CU. */
330 void set_symtab (const dwarf2_per_cu_data
*per_cu
, compunit_symtab
*symtab
);
332 /* Get the type_unit_group_unshareable corresponding to TU_GROUP. If one
333 does not exist, create it. */
334 type_unit_group_unshareable
*get_type_unit_group_unshareable
335 (type_unit_group
*tu_group
);
337 /* Find an integer type SIZE_IN_BYTES bytes in size and return it.
338 UNSIGNED_P controls if the integer is unsigned or not. */
339 struct type
*int_type (int size_in_bytes
, bool unsigned_p
) const;
342 struct objfile
*objfile
;
344 /* Pointer to the data that is (possibly) shared between this objfile and
345 other objfiles backed by the same BFD. */
346 struct dwarf2_per_bfd
*per_bfd
;
348 /* Table mapping type DIEs to their struct type *.
349 This is nullptr if not allocated yet.
350 The mapping is done via (CU/TU + DIE offset) -> type. */
351 htab_up die_type_hash
;
354 /* Hold the corresponding compunit_symtab for each CU or TU. This
355 is indexed by dwarf2_per_cu_data::index. A NULL value means
356 that the CU/TU has not been expanded yet. */
357 std::vector
<compunit_symtab
*> m_symtabs
;
359 /* Map from a type unit group to the corresponding unshared
361 typedef std::unique_ptr
<type_unit_group_unshareable
>
362 type_unit_group_unshareable_up
;
364 std::unordered_map
<type_unit_group
*, type_unit_group_unshareable_up
>
368 /* Get the dwarf2_per_objfile associated to OBJFILE. */
370 dwarf2_per_objfile
*get_dwarf2_per_objfile (struct objfile
*objfile
);
372 /* A partial symtab specialized for DWARF. */
373 struct dwarf2_psymtab
: public partial_symtab
375 dwarf2_psymtab (const char *filename
, struct objfile
*objfile
,
376 dwarf2_per_cu_data
*per_cu
)
377 : partial_symtab (filename
, objfile
, 0),
382 void read_symtab (struct objfile
*) override
;
383 void expand_psymtab (struct objfile
*) override
;
384 bool readin_p (struct objfile
*) const override
;
385 compunit_symtab
*get_compunit_symtab (struct objfile
*) const override
;
387 struct dwarf2_per_cu_data
*per_cu_data
;
390 /* Persistent data held for a compilation unit, even when not
391 processing it. We put a pointer to this structure in the
394 struct dwarf2_per_cu_data
396 /* The start offset and length of this compilation unit.
397 NOTE: Unlike comp_unit_head.length, this length includes
399 If the DIE refers to a DWO file, this is always of the original die,
401 sect_offset sect_off
;
404 /* DWARF standard version this data has been read from (such as 4 or 5). */
407 /* Flag indicating this compilation unit will be read in before
408 any of the current compilation units are processed. */
409 unsigned int queued
: 1;
411 /* This flag will be set when reading partial DIEs if we need to load
412 absolutely all DIEs for this compilation unit, instead of just the ones
413 we think are interesting. It gets set if we look for a DIE in the
414 hash table and don't find it. */
415 unsigned int load_all_dies
: 1;
417 /* Non-zero if this CU is from .debug_types.
418 Struct dwarf2_per_cu_data is contained in struct signatured_type iff
420 unsigned int is_debug_types
: 1;
422 /* Non-zero if this CU is from the .dwz file. */
423 unsigned int is_dwz
: 1;
425 /* Non-zero if reading a TU directly from a DWO file, bypassing the stub.
426 This flag is only valid if is_debug_types is true.
427 We can't read a CU directly from a DWO file: There are required
428 attributes in the stub. */
429 unsigned int reading_dwo_directly
: 1;
431 /* Non-zero if the TU has been read.
432 This is used to assist the "Stay in DWO Optimization" for Fission:
433 When reading a DWO, it's faster to read TUs from the DWO instead of
434 fetching them from random other DWOs (due to comdat folding).
435 If the TU has already been read, the optimization is unnecessary
436 (and unwise - we don't want to change where gdb thinks the TU lives
438 This flag is only valid if is_debug_types is true. */
439 unsigned int tu_read
: 1;
441 /* Our index in the unshared "symtabs" vector. */
444 /* The section this CU/TU lives in.
445 If the DIE refers to a DWO file, this is always the original die,
447 struct dwarf2_section_info
*section
;
449 /* Set to non-NULL iff this CU is currently loaded. When it gets freed out
450 of the CU cache it gets reset to NULL again. This is left as NULL for
451 dummy CUs (a CU header, but nothing else). */
452 struct dwarf2_cu
*cu
;
454 /* The unit type of this CU. */
455 enum dwarf_unit_type unit_type
;
457 /* The language of this CU. */
460 /* Backlink to the owner of this. */
461 dwarf2_per_bfd
*per_bfd
;
463 /* When dwarf2_per_bfd::using_index is true, the 'quick' field
464 is active. Otherwise, the 'psymtab' field is active. */
467 /* The partial symbol table associated with this compilation unit,
468 or NULL for unread partial units. */
469 dwarf2_psymtab
*psymtab
;
471 /* Data needed by the "quick" functions. */
472 struct dwarf2_per_cu_quick_data
*quick
;
475 /* The CUs we import using DW_TAG_imported_unit. This is filled in
476 while reading psymtabs, used to compute the psymtab dependencies,
477 and then cleared. Then it is filled in again while reading full
478 symbols, and only deleted when the objfile is destroyed.
480 This is also used to work around a difference between the way gold
481 generates .gdb_index version <=7 and the way gdb does. Arguably this
482 is a gold bug. For symbols coming from TUs, gold records in the index
483 the CU that includes the TU instead of the TU itself. This breaks
484 dw2_lookup_symbol: It assumes that if the index says symbol X lives
485 in CU/TU Y, then one need only expand Y and a subsequent lookup in Y
486 will find X. Alas TUs live in their own symtab, so after expanding CU Y
487 we need to look in TU Z to find X. Fortunately, this is akin to
488 DW_TAG_imported_unit, so we just use the same mechanism: For
489 .gdb_index version <=7 this also records the TUs that the CU referred
490 to. Concurrently with this change gdb was modified to emit version 8
491 indices so we only pay a price for gold generated indices.
492 http://sourceware.org/bugzilla/show_bug.cgi?id=15021.
494 This currently needs to be a public member due to how
495 dwarf2_per_cu_data is allocated and used. Ideally in future things
496 could be refactored to make this private. Until then please try to
497 avoid direct access to this member, and instead use the helper
499 std::vector
<dwarf2_per_cu_data
*> *imported_symtabs
;
501 /* Return true of IMPORTED_SYMTABS is empty or not yet allocated. */
502 bool imported_symtabs_empty () const
504 return (imported_symtabs
== nullptr || imported_symtabs
->empty ());
507 /* Push P to the back of IMPORTED_SYMTABS, allocated IMPORTED_SYMTABS
508 first if required. */
509 void imported_symtabs_push (dwarf2_per_cu_data
*p
)
511 if (imported_symtabs
== nullptr)
512 imported_symtabs
= new std::vector
<dwarf2_per_cu_data
*>;
513 imported_symtabs
->push_back (p
);
516 /* Return the size of IMPORTED_SYMTABS if it is allocated, otherwise
518 size_t imported_symtabs_size () const
520 if (imported_symtabs
== nullptr)
522 return imported_symtabs
->size ();
525 /* Delete IMPORTED_SYMTABS and set the pointer back to nullptr. */
526 void imported_symtabs_free ()
528 delete imported_symtabs
;
529 imported_symtabs
= nullptr;
532 /* Return the address size given in the compilation unit header for
534 int addr_size () const;
536 /* Return the offset size given in the compilation unit header for
538 int offset_size () const;
540 /* Return the DW_FORM_ref_addr size given in the compilation unit
541 header for this CU. */
542 int ref_addr_size () const;
544 /* Return DWARF version number of this CU. */
545 short version () const
547 return dwarf_version
;
550 /* A type unit group has a per_cu object that is recognized by
551 having no section. */
552 bool type_unit_group_p () const
554 return section
== nullptr;
558 /* Entry in the signatured_types hash table. */
560 struct signatured_type
562 /* The "per_cu" object of this type.
563 This struct is used iff per_cu.is_debug_types.
564 N.B.: This is the first member so that it's easy to convert pointers
566 struct dwarf2_per_cu_data per_cu
;
568 /* The type's signature. */
571 /* Offset in the TU of the type's DIE, as read from the TU header.
572 If this TU is a DWO stub and the definition lives in a DWO file
573 (specified by DW_AT_GNU_dwo_name), this value is unusable. */
574 cu_offset type_offset_in_tu
;
576 /* Offset in the section of the type's DIE.
577 If the definition lives in a DWO file, this is the offset in the
578 .debug_types.dwo section.
579 The value is zero until the actual value is known.
580 Zero is otherwise not a valid section offset. */
581 sect_offset type_offset_in_section
;
583 /* Type units are grouped by their DW_AT_stmt_list entry so that they
584 can share them. This points to the containing symtab. */
585 struct type_unit_group
*type_unit_group
;
588 The first time we encounter this type we fully read it in and install it
589 in the symbol tables. Subsequent times we only need the type. */
592 /* Containing DWO unit.
593 This field is valid iff per_cu.reading_dwo_directly. */
594 struct dwo_unit
*dwo_unit
;
597 /* Open the separate '.dwz' debug file, if needed. Return NULL if
598 there is no .gnu_debugaltlink section in the file. Error if there
599 is such a section but the file cannot be found. */
601 extern dwz_file
*dwarf2_get_dwz_file (dwarf2_per_bfd
*per_bfd
);
603 /* Return the type of the DIE at DIE_OFFSET in the CU named by
606 struct type
*dwarf2_get_die_type (cu_offset die_offset
,
607 dwarf2_per_cu_data
*per_cu
,
608 dwarf2_per_objfile
*per_objfile
);
610 /* Given an index in .debug_addr, fetch the value.
611 NOTE: This can be called during dwarf expression evaluation,
612 long after the debug information has been read, and thus per_cu->cu
613 may no longer exist. */
615 CORE_ADDR
dwarf2_read_addr_index (dwarf2_per_cu_data
*per_cu
,
616 dwarf2_per_objfile
*dwarf2_per_objfile
,
617 unsigned int addr_index
);
619 /* Return DWARF block referenced by DW_AT_location of DIE at SECT_OFF at PER_CU.
620 Returned value is intended for DW_OP_call*. Returned
621 dwarf2_locexpr_baton->data has lifetime of
622 PER_CU->DWARF2_PER_OBJFILE->OBJFILE. */
624 struct dwarf2_locexpr_baton dwarf2_fetch_die_loc_sect_off
625 (sect_offset sect_off
, dwarf2_per_cu_data
*per_cu
,
626 dwarf2_per_objfile
*per_objfile
,
627 CORE_ADDR (*get_frame_pc
) (void *baton
),
628 void *baton
, bool resolve_abstract_p
= false);
630 /* Like dwarf2_fetch_die_loc_sect_off, but take a CU
633 struct dwarf2_locexpr_baton dwarf2_fetch_die_loc_cu_off
634 (cu_offset offset_in_cu
, dwarf2_per_cu_data
*per_cu
,
635 dwarf2_per_objfile
*per_objfile
,
636 CORE_ADDR (*get_frame_pc
) (void *baton
),
639 /* If the DIE at SECT_OFF in PER_CU has a DW_AT_const_value, return a
640 pointer to the constant bytes and set LEN to the length of the
641 data. If memory is needed, allocate it on OBSTACK. If the DIE
642 does not have a DW_AT_const_value, return NULL. */
644 extern const gdb_byte
*dwarf2_fetch_constant_bytes
645 (sect_offset sect_off
, dwarf2_per_cu_data
*per_cu
,
646 dwarf2_per_objfile
*per_objfile
, obstack
*obstack
,
649 /* Return the type of the die at SECT_OFF in PER_CU. Return NULL if no
650 valid type for this die is found. */
652 struct type
*dwarf2_fetch_die_type_sect_off
653 (sect_offset sect_off
, dwarf2_per_cu_data
*per_cu
,
654 dwarf2_per_objfile
*per_objfile
);
656 /* When non-zero, dump line number entries as they are read in. */
657 extern unsigned int dwarf_line_debug
;
659 #endif /* DWARF2READ_H */