1 /* DWARF 2 debugging format support for GDB.
3 Copyright (C) 1994-2019 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/>. */
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"
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
;
33 typedef struct dwarf2_per_cu_data
*dwarf2_per_cu_ptr
;
34 DEF_VEC_P (dwarf2_per_cu_ptr
);
36 extern bool dwarf_always_disassemble
;
38 /* A descriptor for dwarf sections.
40 S.ASECTION, SIZE are typically initialized when the objfile is first
41 scanned. BUFFER, READIN are filled in later when the section is read.
42 If the section contained compressed data then SIZE is updated to record
43 the uncompressed size of the section.
45 DWP file format V2 introduces a wrinkle that is easiest to handle by
46 creating the concept of virtual sections contained within a real section.
47 In DWP V2 the sections of the input DWO files are concatenated together
48 into one section, but section offsets are kept relative to the original
50 If this is a virtual dwp-v2 section, S.CONTAINING_SECTION is a backlink to
51 the real section this "virtual" section is contained in, and BUFFER,SIZE
52 describe the virtual section. */
54 struct dwarf2_section_info
58 /* If this is a real section, the bfd section. */
60 /* If this is a virtual section, pointer to the containing ("real")
62 struct dwarf2_section_info
*containing_section
;
64 /* Pointer to section data, only valid if readin. */
65 const gdb_byte
*buffer
;
66 /* The size of the section, real or virtual. */
68 /* If this is a virtual section, the offset in the real section.
69 Only valid if is_virtual. */
70 bfd_size_type virtual_offset
;
71 /* True if we have tried to read this section. */
73 /* True if this is a virtual section, False otherwise.
74 This specifies which of s.section and s.containing_section to use. */
78 /* Read the contents of the section INFO.
79 OBJFILE is the main object file, but not necessarily the file where
80 the section comes from. E.g., for DWO files the bfd of INFO is the bfd
82 If the section is compressed, uncompress it before returning. */
84 void dwarf2_read_section (struct objfile
*objfile
, dwarf2_section_info
*info
);
88 int nr_uniq_abbrev_tables
;
90 int nr_symtab_sharers
;
91 int nr_stmt_less_type_units
;
92 int nr_all_type_units_reallocs
;
95 struct dwarf2_debug_sections
;
97 struct mapped_debug_names
;
98 struct signatured_type
;
100 typedef struct die_info
*die_info_ptr
;
102 /* Collection of data recorded per objfile.
103 This hangs off of dwarf2_objfile_data_key. */
105 struct dwarf2_per_objfile
107 /* Construct a dwarf2_per_objfile for OBJFILE. NAMES points to the
108 dwarf2 section names, or is NULL if the standard ELF names are
109 used. CAN_COPY is true for formats where symbol
110 interposition is possible and so symbol values must follow copy
112 dwarf2_per_objfile (struct objfile
*objfile
,
113 const dwarf2_debug_sections
*names
,
116 ~dwarf2_per_objfile ();
118 DISABLE_COPY_AND_ASSIGN (dwarf2_per_objfile
);
120 /* Return the CU/TU given its index.
122 This is intended for loops like:
124 for (i = 0; i < (dwarf2_per_objfile->n_comp_units
125 + dwarf2_per_objfile->n_type_units); ++i)
127 dwarf2_per_cu_data *per_cu = dwarf2_per_objfile->get_cutu (i);
132 dwarf2_per_cu_data
*get_cutu (int index
);
134 /* Return the CU given its index.
135 This differs from get_cutu in that it's for when you know INDEX refers to a
137 dwarf2_per_cu_data
*get_cu (int index
);
139 /* Return the TU given its index.
140 This differs from get_cutu in that it's for when you know INDEX refers to a
142 signatured_type
*get_tu (int index
);
144 /* Free all cached compilation units. */
145 void free_cached_comp_units ();
147 /* This function is mapped across the sections and remembers the
148 offset and size of each of the debugging sections we are
150 void locate_sections (bfd
*abfd
, asection
*sectp
,
151 const dwarf2_debug_sections
&names
);
154 dwarf2_section_info info
{};
155 dwarf2_section_info abbrev
{};
156 dwarf2_section_info line
{};
157 dwarf2_section_info loc
{};
158 dwarf2_section_info loclists
{};
159 dwarf2_section_info macinfo
{};
160 dwarf2_section_info macro
{};
161 dwarf2_section_info str
{};
162 dwarf2_section_info line_str
{};
163 dwarf2_section_info ranges
{};
164 dwarf2_section_info rnglists
{};
165 dwarf2_section_info addr
{};
166 dwarf2_section_info frame
{};
167 dwarf2_section_info eh_frame
{};
168 dwarf2_section_info gdb_index
{};
169 dwarf2_section_info debug_names
{};
170 dwarf2_section_info debug_aranges
{};
172 std::vector
<dwarf2_section_info
> types
;
175 struct objfile
*objfile
= NULL
;
177 /* Table of all the compilation units. This is used to locate
178 the target compilation unit of a particular reference. */
179 std::vector
<dwarf2_per_cu_data
*> all_comp_units
;
181 /* The .debug_types-related CUs (TUs). */
182 std::vector
<signatured_type
*> all_type_units
;
184 /* Table of struct type_unit_group objects.
185 The hash key is the DW_AT_stmt_list value. */
186 htab_t type_unit_groups
{};
188 /* A table mapping .debug_types signatures to its signatured_type entry.
189 This is NULL if the .debug_types section hasn't been read in yet. */
190 htab_t signatured_types
{};
192 /* Type unit statistics, to see how well the scaling improvements
194 struct tu_stats tu_stats
{};
196 /* A chain of compilation units that are currently read in, so that
197 they can be freed later. */
198 dwarf2_per_cu_data
*read_in_chain
= NULL
;
200 /* A table mapping DW_AT_dwo_name values to struct dwo_file objects.
201 This is NULL if the table hasn't been allocated yet. */
204 /* True if we've checked for whether there is a DWP file. */
205 bool dwp_checked
= false;
207 /* The DWP file if there is one, or NULL. */
208 std::unique_ptr
<struct dwp_file
> dwp_file
;
210 /* The shared '.dwz' file, if one exists. This is used when the
211 original data was compressed using 'dwz -m'. */
212 std::unique_ptr
<struct dwz_file
> dwz_file
;
214 /* Whether copy relocations are supported by this object format. */
217 /* A flag indicating whether this objfile has a section loaded at a
219 bool has_section_at_zero
= false;
221 /* True if we are using the mapped index,
222 or we are faking it for OBJF_READNOW's sake. */
223 bool using_index
= false;
225 /* The mapped index, or NULL if .gdb_index is missing or not being used. */
226 std::unique_ptr
<mapped_index
> index_table
;
228 /* The mapped index, or NULL if .debug_names is missing or not being used. */
229 std::unique_ptr
<mapped_debug_names
> debug_names_table
;
231 /* When using index_table, this keeps track of all quick_file_names entries.
232 TUs typically share line table entries with a CU, so we maintain a
233 separate table of all line table entries to support the sharing.
234 Note that while there can be way more TUs than CUs, we've already
235 sorted all the TUs into "type unit groups", grouped by their
236 DW_AT_stmt_list value. Therefore the only sharing done here is with a
237 CU and its associated TU group if there is one. */
238 htab_t quick_file_names_table
{};
240 /* Set during partial symbol reading, to prevent queueing of full
242 bool reading_partial_symbols
= false;
244 /* Table mapping type DIEs to their struct type *.
245 This is NULL if not allocated yet.
246 The mapping is done via (CU/TU + DIE offset) -> type. */
247 htab_t die_type_hash
{};
249 /* The CUs we recently read. */
250 std::vector
<dwarf2_per_cu_data
*> just_read_cus
;
252 /* Table containing line_header indexed by offset and offset_in_dwz. */
253 htab_t line_header_hash
{};
255 /* Table containing all filenames. This is an optional because the
256 table is lazily constructed on first access. */
257 gdb::optional
<filename_seen_cache
> filenames_cache
;
259 /* If we loaded the index from an external file, this contains the
260 resources associated to the open file, memory mapping, etc. */
261 std::unique_ptr
<index_cache_resource
> index_cache_res
;
263 /* Mapping from abstract origin DIE to concrete DIEs that reference it as
264 DW_AT_abstract_origin. */
265 std::unordered_map
<sect_offset
, std::vector
<sect_offset
>, \
266 gdb::hash_enum
<sect_offset
>> \
267 abstract_to_concrete
;
270 /* Get the dwarf2_per_objfile associated to OBJFILE. */
272 dwarf2_per_objfile
*get_dwarf2_per_objfile (struct objfile
*objfile
);
274 /* Persistent data held for a compilation unit, even when not
275 processing it. We put a pointer to this structure in the
276 read_symtab_private field of the psymtab. */
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 corresponding dwarf2_per_objfile. */
336 struct dwarf2_per_objfile
*dwarf2_per_objfile
;
338 /* When dwarf2_per_objfile->using_index is true, the 'quick' field
339 is active. Otherwise, the 'psymtab' field is active. */
342 /* The partial symbol table associated with this compilation unit,
343 or NULL for unread partial units. */
344 struct partial_symtab
*psymtab
;
346 /* Data needed by the "quick" functions. */
347 struct dwarf2_per_cu_quick_data
*quick
;
350 /* The CUs we import using DW_TAG_imported_unit. This is filled in
351 while reading psymtabs, used to compute the psymtab dependencies,
352 and then cleared. Then it is filled in again while reading full
353 symbols, and only deleted when the objfile is destroyed.
355 This is also used to work around a difference between the way gold
356 generates .gdb_index version <=7 and the way gdb does. Arguably this
357 is a gold bug. For symbols coming from TUs, gold records in the index
358 the CU that includes the TU instead of the TU itself. This breaks
359 dw2_lookup_symbol: It assumes that if the index says symbol X lives
360 in CU/TU Y, then one need only expand Y and a subsequent lookup in Y
361 will find X. Alas TUs live in their own symtab, so after expanding CU Y
362 we need to look in TU Z to find X. Fortunately, this is akin to
363 DW_TAG_imported_unit, so we just use the same mechanism: For
364 .gdb_index version <=7 this also records the TUs that the CU referred
365 to. Concurrently with this change gdb was modified to emit version 8
366 indices so we only pay a price for gold generated indices.
367 http://sourceware.org/bugzilla/show_bug.cgi?id=15021. */
368 VEC (dwarf2_per_cu_ptr
) *imported_symtabs
;
371 /* Entry in the signatured_types hash table. */
373 struct signatured_type
375 /* The "per_cu" object of this type.
376 This struct is used iff per_cu.is_debug_types.
377 N.B.: This is the first member so that it's easy to convert pointers
379 struct dwarf2_per_cu_data per_cu
;
381 /* The type's signature. */
384 /* Offset in the TU of the type's DIE, as read from the TU header.
385 If this TU is a DWO stub and the definition lives in a DWO file
386 (specified by DW_AT_GNU_dwo_name), this value is unusable. */
387 cu_offset type_offset_in_tu
;
389 /* Offset in the section of the type's DIE.
390 If the definition lives in a DWO file, this is the offset in the
391 .debug_types.dwo section.
392 The value is zero until the actual value is known.
393 Zero is otherwise not a valid section offset. */
394 sect_offset type_offset_in_section
;
396 /* Type units are grouped by their DW_AT_stmt_list entry so that they
397 can share them. This points to the containing symtab. */
398 struct type_unit_group
*type_unit_group
;
401 The first time we encounter this type we fully read it in and install it
402 in the symbol tables. Subsequent times we only need the type. */
405 /* Containing DWO unit.
406 This field is valid iff per_cu.reading_dwo_directly. */
407 struct dwo_unit
*dwo_unit
;
410 ULONGEST
read_unsigned_leb128 (bfd
*, const gdb_byte
*, unsigned int *);
412 /* This represents a '.dwz' file. */
416 dwz_file (gdb_bfd_ref_ptr
&&bfd
)
417 : dwz_bfd (std::move (bfd
))
421 const char *filename () const
423 return bfd_get_filename (this->dwz_bfd
.get ());
426 /* A dwz file can only contain a few sections. */
427 struct dwarf2_section_info abbrev
{};
428 struct dwarf2_section_info info
{};
429 struct dwarf2_section_info str
{};
430 struct dwarf2_section_info line
{};
431 struct dwarf2_section_info macro
{};
432 struct dwarf2_section_info gdb_index
{};
433 struct dwarf2_section_info debug_names
{};
436 gdb_bfd_ref_ptr dwz_bfd
;
438 /* If we loaded the index from an external file, this contains the
439 resources associated to the open file, memory mapping, etc. */
440 std::unique_ptr
<index_cache_resource
> index_cache_res
;
443 /* Open the separate '.dwz' debug file, if needed. Return NULL if
444 there is no .gnu_debugaltlink section in the file. Error if there
445 is such a section but the file cannot be found. */
447 extern struct dwz_file
*dwarf2_get_dwz_file
448 (struct dwarf2_per_objfile
*dwarf2_per_objfile
);
450 #endif /* DWARF2READ_H */