1 /* DWARF 2 debugging format support for GDB.
3 Copyright (C) 1994-2018 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 "filename-seen-cache.h"
24 #include "gdb_obstack.h"
26 typedef struct dwarf2_per_cu_data
*dwarf2_per_cu_ptr
;
27 DEF_VEC_P (dwarf2_per_cu_ptr
);
29 /* A descriptor for dwarf sections.
31 S.ASECTION, SIZE are typically initialized when the objfile is first
32 scanned. BUFFER, READIN are filled in later when the section is read.
33 If the section contained compressed data then SIZE is updated to record
34 the uncompressed size of the section.
36 DWP file format V2 introduces a wrinkle that is easiest to handle by
37 creating the concept of virtual sections contained within a real section.
38 In DWP V2 the sections of the input DWO files are concatenated together
39 into one section, but section offsets are kept relative to the original
41 If this is a virtual dwp-v2 section, S.CONTAINING_SECTION is a backlink to
42 the real section this "virtual" section is contained in, and BUFFER,SIZE
43 describe the virtual section. */
45 struct dwarf2_section_info
49 /* If this is a real section, the bfd section. */
51 /* If this is a virtual section, pointer to the containing ("real")
53 struct dwarf2_section_info
*containing_section
;
55 /* Pointer to section data, only valid if readin. */
56 const gdb_byte
*buffer
;
57 /* The size of the section, real or virtual. */
59 /* If this is a virtual section, the offset in the real section.
60 Only valid if is_virtual. */
61 bfd_size_type virtual_offset
;
62 /* True if we have tried to read this section. */
64 /* True if this is a virtual section, False otherwise.
65 This specifies which of s.section and s.containing_section to use. */
69 typedef struct dwarf2_section_info dwarf2_section_info_def
;
70 DEF_VEC_O (dwarf2_section_info_def
);
72 /* Read the contents of the section INFO.
73 OBJFILE is the main object file, but not necessarily the file where
74 the section comes from. E.g., for DWO files the bfd of INFO is the bfd
76 If the section is compressed, uncompress it before returning. */
78 void dwarf2_read_section (struct objfile
*objfile
, dwarf2_section_info
*info
);
82 int nr_uniq_abbrev_tables
;
84 int nr_symtab_sharers
;
85 int nr_stmt_less_type_units
;
86 int nr_all_type_units_reallocs
;
89 struct dwarf2_debug_sections
;
91 struct mapped_debug_names
;
93 /* Collection of data recorded per objfile.
94 This hangs off of dwarf2_objfile_data_key. */
96 struct dwarf2_per_objfile
: public allocate_on_obstack
98 /* Construct a dwarf2_per_objfile for OBJFILE. NAMES points to the
99 dwarf2 section names, or is NULL if the standard ELF names are
101 dwarf2_per_objfile (struct objfile
*objfile
,
102 const dwarf2_debug_sections
*names
);
104 ~dwarf2_per_objfile ();
106 DISABLE_COPY_AND_ASSIGN (dwarf2_per_objfile
);
108 /* Free all cached compilation units. */
109 void free_cached_comp_units ();
111 /* This function is mapped across the sections and remembers the
112 offset and size of each of the debugging sections we are
114 void locate_sections (bfd
*abfd
, asection
*sectp
,
115 const dwarf2_debug_sections
&names
);
118 dwarf2_section_info info
{};
119 dwarf2_section_info abbrev
{};
120 dwarf2_section_info line
{};
121 dwarf2_section_info loc
{};
122 dwarf2_section_info loclists
{};
123 dwarf2_section_info macinfo
{};
124 dwarf2_section_info macro
{};
125 dwarf2_section_info str
{};
126 dwarf2_section_info line_str
{};
127 dwarf2_section_info ranges
{};
128 dwarf2_section_info rnglists
{};
129 dwarf2_section_info addr
{};
130 dwarf2_section_info frame
{};
131 dwarf2_section_info eh_frame
{};
132 dwarf2_section_info gdb_index
{};
133 dwarf2_section_info debug_names
{};
134 dwarf2_section_info debug_aranges
{};
136 VEC (dwarf2_section_info_def
) *types
= NULL
;
139 struct objfile
*objfile
= NULL
;
141 /* Table of all the compilation units. This is used to locate
142 the target compilation unit of a particular reference. */
143 struct dwarf2_per_cu_data
**all_comp_units
= NULL
;
145 /* The number of compilation units in ALL_COMP_UNITS. */
146 int n_comp_units
= 0;
148 /* The number of .debug_types-related CUs. */
149 int n_type_units
= 0;
151 /* The number of elements allocated in all_type_units.
152 If there are skeleton-less TUs, we add them to all_type_units lazily. */
153 int n_allocated_type_units
= 0;
155 /* The .debug_types-related CUs (TUs).
156 This is stored in malloc space because we may realloc it. */
157 struct signatured_type
**all_type_units
= NULL
;
159 /* Table of struct type_unit_group objects.
160 The hash key is the DW_AT_stmt_list value. */
161 htab_t type_unit_groups
{};
163 /* A table mapping .debug_types signatures to its signatured_type entry.
164 This is NULL if the .debug_types section hasn't been read in yet. */
165 htab_t signatured_types
{};
167 /* Type unit statistics, to see how well the scaling improvements
169 struct tu_stats tu_stats
{};
171 /* A chain of compilation units that are currently read in, so that
172 they can be freed later. */
173 dwarf2_per_cu_data
*read_in_chain
= NULL
;
175 /* A table mapping DW_AT_dwo_name values to struct dwo_file objects.
176 This is NULL if the table hasn't been allocated yet. */
179 /* True if we've checked for whether there is a DWP file. */
180 bool dwp_checked
= false;
182 /* The DWP file if there is one, or NULL. */
183 struct dwp_file
*dwp_file
= NULL
;
185 /* The shared '.dwz' file, if one exists. This is used when the
186 original data was compressed using 'dwz -m'. */
187 struct dwz_file
*dwz_file
= NULL
;
189 /* A flag indicating whether this objfile has a section loaded at a
191 bool has_section_at_zero
= false;
193 /* True if we are using the mapped index,
194 or we are faking it for OBJF_READNOW's sake. */
195 bool using_index
= false;
197 /* The mapped index, or NULL if .gdb_index is missing or not being used. */
198 mapped_index
*index_table
= NULL
;
200 /* The mapped index, or NULL if .debug_names is missing or not being used. */
201 std::unique_ptr
<mapped_debug_names
> debug_names_table
;
203 /* When using index_table, this keeps track of all quick_file_names entries.
204 TUs typically share line table entries with a CU, so we maintain a
205 separate table of all line table entries to support the sharing.
206 Note that while there can be way more TUs than CUs, we've already
207 sorted all the TUs into "type unit groups", grouped by their
208 DW_AT_stmt_list value. Therefore the only sharing done here is with a
209 CU and its associated TU group if there is one. */
210 htab_t quick_file_names_table
{};
212 /* Set during partial symbol reading, to prevent queueing of full
214 bool reading_partial_symbols
= false;
216 /* Table mapping type DIEs to their struct type *.
217 This is NULL if not allocated yet.
218 The mapping is done via (CU/TU + DIE offset) -> type. */
219 htab_t die_type_hash
{};
221 /* The CUs we recently read. */
222 VEC (dwarf2_per_cu_ptr
) *just_read_cus
= NULL
;
224 /* Table containing line_header indexed by offset and offset_in_dwz. */
225 htab_t line_header_hash
{};
227 /* Table containing all filenames. This is an optional because the
228 table is lazily constructed on first access. */
229 gdb::optional
<filename_seen_cache
> filenames_cache
;
232 /* Get the dwarf2_per_objfile associated to OBJFILE. */
234 dwarf2_per_objfile
*get_dwarf2_per_objfile (struct objfile
*objfile
);
236 /* Persistent data held for a compilation unit, even when not
237 processing it. We put a pointer to this structure in the
238 read_symtab_private field of the psymtab. */
240 struct dwarf2_per_cu_data
242 /* The start offset and length of this compilation unit.
243 NOTE: Unlike comp_unit_head.length, this length includes
245 If the DIE refers to a DWO file, this is always of the original die,
247 sect_offset sect_off
;
250 /* DWARF standard version this data has been read from (such as 4 or 5). */
253 /* Flag indicating this compilation unit will be read in before
254 any of the current compilation units are processed. */
255 unsigned int queued
: 1;
257 /* This flag will be set when reading partial DIEs if we need to load
258 absolutely all DIEs for this compilation unit, instead of just the ones
259 we think are interesting. It gets set if we look for a DIE in the
260 hash table and don't find it. */
261 unsigned int load_all_dies
: 1;
263 /* Non-zero if this CU is from .debug_types.
264 Struct dwarf2_per_cu_data is contained in struct signatured_type iff
266 unsigned int is_debug_types
: 1;
268 /* Non-zero if this CU is from the .dwz file. */
269 unsigned int is_dwz
: 1;
271 /* Non-zero if reading a TU directly from a DWO file, bypassing the stub.
272 This flag is only valid if is_debug_types is true.
273 We can't read a CU directly from a DWO file: There are required
274 attributes in the stub. */
275 unsigned int reading_dwo_directly
: 1;
277 /* Non-zero if the TU has been read.
278 This is used to assist the "Stay in DWO Optimization" for Fission:
279 When reading a DWO, it's faster to read TUs from the DWO instead of
280 fetching them from random other DWOs (due to comdat folding).
281 If the TU has already been read, the optimization is unnecessary
282 (and unwise - we don't want to change where gdb thinks the TU lives
284 This flag is only valid if is_debug_types is true. */
285 unsigned int tu_read
: 1;
287 /* The section this CU/TU lives in.
288 If the DIE refers to a DWO file, this is always the original die,
290 struct dwarf2_section_info
*section
;
292 /* Set to non-NULL iff this CU is currently loaded. When it gets freed out
293 of the CU cache it gets reset to NULL again. This is left as NULL for
294 dummy CUs (a CU header, but nothing else). */
295 struct dwarf2_cu
*cu
;
297 /* The corresponding dwarf2_per_objfile. */
298 struct dwarf2_per_objfile
*dwarf2_per_objfile
;
300 /* When dwarf2_per_objfile->using_index is true, the 'quick' field
301 is active. Otherwise, the 'psymtab' field is active. */
304 /* The partial symbol table associated with this compilation unit,
305 or NULL for unread partial units. */
306 struct partial_symtab
*psymtab
;
308 /* Data needed by the "quick" functions. */
309 struct dwarf2_per_cu_quick_data
*quick
;
312 /* The CUs we import using DW_TAG_imported_unit. This is filled in
313 while reading psymtabs, used to compute the psymtab dependencies,
314 and then cleared. Then it is filled in again while reading full
315 symbols, and only deleted when the objfile is destroyed.
317 This is also used to work around a difference between the way gold
318 generates .gdb_index version <=7 and the way gdb does. Arguably this
319 is a gold bug. For symbols coming from TUs, gold records in the index
320 the CU that includes the TU instead of the TU itself. This breaks
321 dw2_lookup_symbol: It assumes that if the index says symbol X lives
322 in CU/TU Y, then one need only expand Y and a subsequent lookup in Y
323 will find X. Alas TUs live in their own symtab, so after expanding CU Y
324 we need to look in TU Z to find X. Fortunately, this is akin to
325 DW_TAG_imported_unit, so we just use the same mechanism: For
326 .gdb_index version <=7 this also records the TUs that the CU referred
327 to. Concurrently with this change gdb was modified to emit version 8
328 indices so we only pay a price for gold generated indices.
329 http://sourceware.org/bugzilla/show_bug.cgi?id=15021. */
330 VEC (dwarf2_per_cu_ptr
) *imported_symtabs
;
333 /* Entry in the signatured_types hash table. */
335 struct signatured_type
337 /* The "per_cu" object of this type.
338 This struct is used iff per_cu.is_debug_types.
339 N.B.: This is the first member so that it's easy to convert pointers
341 struct dwarf2_per_cu_data per_cu
;
343 /* The type's signature. */
346 /* Offset in the TU of the type's DIE, as read from the TU header.
347 If this TU is a DWO stub and the definition lives in a DWO file
348 (specified by DW_AT_GNU_dwo_name), this value is unusable. */
349 cu_offset type_offset_in_tu
;
351 /* Offset in the section of the type's DIE.
352 If the definition lives in a DWO file, this is the offset in the
353 .debug_types.dwo section.
354 The value is zero until the actual value is known.
355 Zero is otherwise not a valid section offset. */
356 sect_offset type_offset_in_section
;
358 /* Type units are grouped by their DW_AT_stmt_list entry so that they
359 can share them. This points to the containing symtab. */
360 struct type_unit_group
*type_unit_group
;
363 The first time we encounter this type we fully read it in and install it
364 in the symbol tables. Subsequent times we only need the type. */
367 /* Containing DWO unit.
368 This field is valid iff per_cu.reading_dwo_directly. */
369 struct dwo_unit
*dwo_unit
;
372 typedef struct signatured_type
*sig_type_ptr
;
373 DEF_VEC_P (sig_type_ptr
);
375 #endif /* DWARF2READ_H */