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
;
36 extern bool dwarf_always_disassemble
;
40 int nr_uniq_abbrev_tables
;
42 int nr_symtab_sharers
;
43 int nr_stmt_less_type_units
;
44 int nr_all_type_units_reallocs
;
47 struct dwarf2_debug_sections
;
48 struct dwarf2_per_cu_data
;
50 struct mapped_debug_names
;
51 struct signatured_type
;
53 /* One item on the queue of compilation units to read in full symbols
55 struct dwarf2_queue_item
57 dwarf2_queue_item (dwarf2_per_cu_data
*cu
, enum language lang
)
59 pretend_language (lang
)
63 ~dwarf2_queue_item ();
65 DISABLE_COPY_AND_ASSIGN (dwarf2_queue_item
);
67 struct dwarf2_per_cu_data
*per_cu
;
68 enum language pretend_language
;
71 /* Collection of data recorded per objfile.
72 This hangs off of dwarf2_objfile_data_key. */
74 struct dwarf2_per_objfile
76 /* Construct a dwarf2_per_objfile for OBJFILE. NAMES points to the
77 dwarf2 section names, or is NULL if the standard ELF names are
78 used. CAN_COPY is true for formats where symbol
79 interposition is possible and so symbol values must follow copy
81 dwarf2_per_objfile (struct objfile
*objfile
,
82 const dwarf2_debug_sections
*names
,
85 ~dwarf2_per_objfile ();
87 DISABLE_COPY_AND_ASSIGN (dwarf2_per_objfile
);
89 /* Return the CU/TU given its index.
91 This is intended for loops like:
93 for (i = 0; i < (dwarf2_per_objfile->n_comp_units
94 + dwarf2_per_objfile->n_type_units); ++i)
96 dwarf2_per_cu_data *per_cu = dwarf2_per_objfile->get_cutu (i);
101 dwarf2_per_cu_data
*get_cutu (int index
);
103 /* Return the CU given its index.
104 This differs from get_cutu in that it's for when you know INDEX refers to a
106 dwarf2_per_cu_data
*get_cu (int index
);
108 /* Return the TU given its index.
109 This differs from get_cutu in that it's for when you know INDEX refers to a
111 signatured_type
*get_tu (int index
);
113 /* Free all cached compilation units. */
114 void free_cached_comp_units ();
116 /* This function is mapped across the sections and remembers the
117 offset and size of each of the debugging sections we are
119 void locate_sections (bfd
*abfd
, asection
*sectp
,
120 const dwarf2_debug_sections
&names
);
123 dwarf2_section_info info
{};
124 dwarf2_section_info abbrev
{};
125 dwarf2_section_info line
{};
126 dwarf2_section_info loc
{};
127 dwarf2_section_info loclists
{};
128 dwarf2_section_info macinfo
{};
129 dwarf2_section_info macro
{};
130 dwarf2_section_info str
{};
131 dwarf2_section_info str_offsets
{};
132 dwarf2_section_info line_str
{};
133 dwarf2_section_info ranges
{};
134 dwarf2_section_info rnglists
{};
135 dwarf2_section_info addr
{};
136 dwarf2_section_info frame
{};
137 dwarf2_section_info eh_frame
{};
138 dwarf2_section_info gdb_index
{};
139 dwarf2_section_info debug_names
{};
140 dwarf2_section_info debug_aranges
{};
142 std::vector
<dwarf2_section_info
> types
;
145 struct objfile
*objfile
= NULL
;
147 /* Table of all the compilation units. This is used to locate
148 the target compilation unit of a particular reference. */
149 std::vector
<dwarf2_per_cu_data
*> all_comp_units
;
151 /* The .debug_types-related CUs (TUs). */
152 std::vector
<signatured_type
*> all_type_units
;
154 /* Table of struct type_unit_group objects.
155 The hash key is the DW_AT_stmt_list value. */
156 htab_t type_unit_groups
{};
158 /* A table mapping .debug_types signatures to its signatured_type entry.
159 This is NULL if the .debug_types section hasn't been read in yet. */
160 htab_t signatured_types
{};
162 /* Type unit statistics, to see how well the scaling improvements
164 struct tu_stats tu_stats
{};
166 /* A chain of compilation units that are currently read in, so that
167 they can be freed later. */
168 dwarf2_per_cu_data
*read_in_chain
= NULL
;
170 /* A table mapping DW_AT_dwo_name values to struct dwo_file objects.
171 This is NULL if the table hasn't been allocated yet. */
174 /* True if we've checked for whether there is a DWP file. */
175 bool dwp_checked
= false;
177 /* The DWP file if there is one, or NULL. */
178 std::unique_ptr
<struct dwp_file
> dwp_file
;
180 /* The shared '.dwz' file, if one exists. This is used when the
181 original data was compressed using 'dwz -m'. */
182 std::unique_ptr
<struct dwz_file
> dwz_file
;
184 /* Whether copy relocations are supported by this object format. */
187 /* A flag indicating whether this objfile has a section loaded at a
189 bool has_section_at_zero
= false;
191 /* True if we are using the mapped index,
192 or we are faking it for OBJF_READNOW's sake. */
193 bool using_index
= false;
195 /* The mapped index, or NULL if .gdb_index is missing or not being used. */
196 std::unique_ptr
<mapped_index
> index_table
;
198 /* The mapped index, or NULL if .debug_names is missing or not being used. */
199 std::unique_ptr
<mapped_debug_names
> debug_names_table
;
201 /* When using index_table, this keeps track of all quick_file_names entries.
202 TUs typically share line table entries with a CU, so we maintain a
203 separate table of all line table entries to support the sharing.
204 Note that while there can be way more TUs than CUs, we've already
205 sorted all the TUs into "type unit groups", grouped by their
206 DW_AT_stmt_list value. Therefore the only sharing done here is with a
207 CU and its associated TU group if there is one. */
208 htab_t quick_file_names_table
{};
210 /* Set during partial symbol reading, to prevent queueing of full
212 bool reading_partial_symbols
= false;
214 /* Table mapping type DIEs to their struct type *.
215 This is NULL if not allocated yet.
216 The mapping is done via (CU/TU + DIE offset) -> type. */
217 htab_t die_type_hash
{};
219 /* The CUs we recently read. */
220 std::vector
<dwarf2_per_cu_data
*> just_read_cus
;
222 /* Table containing line_header indexed by offset and offset_in_dwz. */
223 htab_t line_header_hash
{};
225 /* Table containing all filenames. This is an optional because the
226 table is lazily constructed on first access. */
227 gdb::optional
<filename_seen_cache
> filenames_cache
;
229 /* If we loaded the index from an external file, this contains the
230 resources associated to the open file, memory mapping, etc. */
231 std::unique_ptr
<index_cache_resource
> index_cache_res
;
233 /* Mapping from abstract origin DIE to concrete DIEs that reference it as
234 DW_AT_abstract_origin. */
235 std::unordered_map
<sect_offset
, std::vector
<sect_offset
>,
236 gdb::hash_enum
<sect_offset
>>
237 abstract_to_concrete
;
239 /* CUs that are queued to be read. */
240 std::queue
<dwarf2_queue_item
> queue
;
243 /* Get the dwarf2_per_objfile associated to OBJFILE. */
245 dwarf2_per_objfile
*get_dwarf2_per_objfile (struct objfile
*objfile
);
247 /* A partial symtab specialized for DWARF. */
248 struct dwarf2_psymtab
: public standard_psymtab
250 dwarf2_psymtab (const char *filename
, struct objfile
*objfile
)
251 : standard_psymtab (filename
, objfile
)
255 dwarf2_psymtab (const char *filename
, struct objfile
*objfile
,
257 : standard_psymtab (filename
, objfile
, addr
)
261 void read_symtab (struct objfile
*) override
;
262 void expand_psymtab (struct objfile
*) override
;
264 struct dwarf2_per_cu_data
*per_cu_data
;
267 /* Persistent data held for a compilation unit, even when not
268 processing it. We put a pointer to this structure in the
271 struct dwarf2_per_cu_data
273 /* The start offset and length of this compilation unit.
274 NOTE: Unlike comp_unit_head.length, this length includes
276 If the DIE refers to a DWO file, this is always of the original die,
278 sect_offset sect_off
;
281 /* DWARF standard version this data has been read from (such as 4 or 5). */
284 /* Flag indicating this compilation unit will be read in before
285 any of the current compilation units are processed. */
286 unsigned int queued
: 1;
288 /* This flag will be set when reading partial DIEs if we need to load
289 absolutely all DIEs for this compilation unit, instead of just the ones
290 we think are interesting. It gets set if we look for a DIE in the
291 hash table and don't find it. */
292 unsigned int load_all_dies
: 1;
294 /* Non-zero if this CU is from .debug_types.
295 Struct dwarf2_per_cu_data is contained in struct signatured_type iff
297 unsigned int is_debug_types
: 1;
299 /* Non-zero if this CU is from the .dwz file. */
300 unsigned int is_dwz
: 1;
302 /* Non-zero if reading a TU directly from a DWO file, bypassing the stub.
303 This flag is only valid if is_debug_types is true.
304 We can't read a CU directly from a DWO file: There are required
305 attributes in the stub. */
306 unsigned int reading_dwo_directly
: 1;
308 /* Non-zero if the TU has been read.
309 This is used to assist the "Stay in DWO Optimization" for Fission:
310 When reading a DWO, it's faster to read TUs from the DWO instead of
311 fetching them from random other DWOs (due to comdat folding).
312 If the TU has already been read, the optimization is unnecessary
313 (and unwise - we don't want to change where gdb thinks the TU lives
315 This flag is only valid if is_debug_types is true. */
316 unsigned int tu_read
: 1;
318 /* The section this CU/TU lives in.
319 If the DIE refers to a DWO file, this is always the original die,
321 struct dwarf2_section_info
*section
;
323 /* Set to non-NULL iff this CU is currently loaded. When it gets freed out
324 of the CU cache it gets reset to NULL again. This is left as NULL for
325 dummy CUs (a CU header, but nothing else). */
326 struct dwarf2_cu
*cu
;
328 /* The corresponding dwarf2_per_objfile. */
329 struct dwarf2_per_objfile
*dwarf2_per_objfile
;
331 /* When dwarf2_per_objfile->using_index is true, the 'quick' field
332 is active. Otherwise, the 'psymtab' field is active. */
335 /* The partial symbol table associated with this compilation unit,
336 or NULL for unread partial units. */
337 dwarf2_psymtab
*psymtab
;
339 /* Data needed by the "quick" functions. */
340 struct dwarf2_per_cu_quick_data
*quick
;
343 /* Return true of IMPORTED_SYMTABS is empty or not yet allocated. */
344 bool imported_symtabs_empty () const
346 return (imported_symtabs
== nullptr || imported_symtabs
->empty ());
349 /* Push P to the back of IMPORTED_SYMTABS, allocated IMPORTED_SYMTABS
350 first if required. */
351 void imported_symtabs_push (dwarf2_per_cu_data
*p
)
353 if (imported_symtabs
== nullptr)
354 imported_symtabs
= new std::vector
<dwarf2_per_cu_data
*>;
355 imported_symtabs
->push_back (p
);
358 /* Return the size of IMPORTED_SYMTABS if it is allocated, otherwise
360 size_t imported_symtabs_size () const
362 if (imported_symtabs
== nullptr)
364 return imported_symtabs
->size ();
367 /* Delete IMPORTED_SYMTABS and set the pointer back to nullptr. */
368 void imported_symtabs_free ()
370 delete imported_symtabs
;
371 imported_symtabs
= nullptr;
374 /* The CUs we import using DW_TAG_imported_unit. This is filled in
375 while reading psymtabs, used to compute the psymtab dependencies,
376 and then cleared. Then it is filled in again while reading full
377 symbols, and only deleted when the objfile is destroyed.
379 This is also used to work around a difference between the way gold
380 generates .gdb_index version <=7 and the way gdb does. Arguably this
381 is a gold bug. For symbols coming from TUs, gold records in the index
382 the CU that includes the TU instead of the TU itself. This breaks
383 dw2_lookup_symbol: It assumes that if the index says symbol X lives
384 in CU/TU Y, then one need only expand Y and a subsequent lookup in Y
385 will find X. Alas TUs live in their own symtab, so after expanding CU Y
386 we need to look in TU Z to find X. Fortunately, this is akin to
387 DW_TAG_imported_unit, so we just use the same mechanism: For
388 .gdb_index version <=7 this also records the TUs that the CU referred
389 to. Concurrently with this change gdb was modified to emit version 8
390 indices so we only pay a price for gold generated indices.
391 http://sourceware.org/bugzilla/show_bug.cgi?id=15021.
393 This currently needs to be a public member due to how
394 dwarf2_per_cu_data is allocated and used. Ideally in future things
395 could be refactored to make this private. Until then please try to
396 avoid direct access to this member, and instead use the helper
398 std::vector
<dwarf2_per_cu_data
*> *imported_symtabs
;
401 /* Entry in the signatured_types hash table. */
403 struct signatured_type
405 /* The "per_cu" object of this type.
406 This struct is used iff per_cu.is_debug_types.
407 N.B.: This is the first member so that it's easy to convert pointers
409 struct dwarf2_per_cu_data per_cu
;
411 /* The type's signature. */
414 /* Offset in the TU of the type's DIE, as read from the TU header.
415 If this TU is a DWO stub and the definition lives in a DWO file
416 (specified by DW_AT_GNU_dwo_name), this value is unusable. */
417 cu_offset type_offset_in_tu
;
419 /* Offset in the section of the type's DIE.
420 If the definition lives in a DWO file, this is the offset in the
421 .debug_types.dwo section.
422 The value is zero until the actual value is known.
423 Zero is otherwise not a valid section offset. */
424 sect_offset type_offset_in_section
;
426 /* Type units are grouped by their DW_AT_stmt_list entry so that they
427 can share them. This points to the containing symtab. */
428 struct type_unit_group
*type_unit_group
;
431 The first time we encounter this type we fully read it in and install it
432 in the symbol tables. Subsequent times we only need the type. */
435 /* Containing DWO unit.
436 This field is valid iff per_cu.reading_dwo_directly. */
437 struct dwo_unit
*dwo_unit
;
440 /* This represents a '.dwz' file. */
444 dwz_file (gdb_bfd_ref_ptr
&&bfd
)
445 : dwz_bfd (std::move (bfd
))
449 const char *filename () const
451 return bfd_get_filename (this->dwz_bfd
.get ());
454 /* A dwz file can only contain a few sections. */
455 struct dwarf2_section_info abbrev
{};
456 struct dwarf2_section_info info
{};
457 struct dwarf2_section_info str
{};
458 struct dwarf2_section_info line
{};
459 struct dwarf2_section_info macro
{};
460 struct dwarf2_section_info gdb_index
{};
461 struct dwarf2_section_info debug_names
{};
464 gdb_bfd_ref_ptr dwz_bfd
;
466 /* If we loaded the index from an external file, this contains the
467 resources associated to the open file, memory mapping, etc. */
468 std::unique_ptr
<index_cache_resource
> index_cache_res
;
471 /* Open the separate '.dwz' debug file, if needed. Return NULL if
472 there is no .gnu_debugaltlink section in the file. Error if there
473 is such a section but the file cannot be found. */
475 extern struct dwz_file
*dwarf2_get_dwz_file
476 (struct dwarf2_per_objfile
*dwarf2_per_objfile
);
478 #endif /* DWARF2READ_H */